This Data Terminal was Covered in Poop!

[@Llamarama100]

Power electronics engineer here specialising in MRO of rail power electronics. You're cleaning the boards exactly how I would, only think I would change would be to add Isopropyl alcohol to sterilise and act as a drying agent.

[@kensmith5694]

Some old capacitors wouldn't be happy with much time with isopropyl. Polystyrene capacitors will degrade. I have also had cases of it attacking coax cables. The insulation between the center conductor and the shield seemed to soak up the isopropyl and distort.

[@adamboggs4745]

I this case it's more of a rinse instead of a soak in the IPA though, right? Just enough to help get rid of any residual water and unwanted microbiome...

[@lelandclayton5462]

I agree, However I wouldn't use a high percentage of alcohol, maybe the strongest you can get from the first aid section at the store.

[@christo930]

Do you have anything against cleaning it with an ultrasonic cleaner?

[@kensmith5694]

@@christo930 It may be too aggressive.

[@UnimplementedTrapChannel]

Sure that terminal is gorgeous, but I spent the whole episode drooling over that cute HP multimeter

[@tommythorn]

I could stare at those gorgeous 7-segments all day.

[@timothydelaval1089]

Those desctop meters are amazing I have a 1970s simpson meter that has a nixie tube display.

[@TheDiveO]

it looks as if it would spring right into your face when you apply wrong voltage

[@geofftaylor8913]

@@timothydelaval1089you lucky dog. I have a Simpson multimeter that has early LEDs. Pretty rare I believe. Maybe not.

[@nigefoxx]

Much better than propping a clamp meter up with a screwdriver!

[@hessex1899]

That thing is more 70's than a Foghat 8-track. Absolutely outstanding. :)

[@ChrisPinCornwall]

Wow Foghat...I'd forgotten! 👌

[@ChristopherHailey]

Wow, flask back to my college days!

[@ChristopherHailey]

"flash"

[@KameraShy]

RIP Lonesome Dave.

[@UsagiElectric]

"Slow ride, take it easy!"

[@kenromaine2387]

Just saw the part of the video showing a large number of ((( ( (( ( in a field of what should be ASCII spaces. I would bet the ((( ( (( ( because the error in the raster display is in the middle grouping of 8 lines the issue is with the ADDS memory shift-reg card's 9 Shit-Reg. ICs, one of the chips is flipping bits because it's just bad, ( This was a very common problem and many time was heat related. ) Space code = 0x20 and the ( code = 0x28 looks like a bad shift-reg bit.

[@horusfalcon]

Nicely spotted!

[@UsagiElectric]

Ken swinging in with the proper expert diagnosis! Gonna have to get you down here to help get this thing and the printer fully up and running one of these days!

[@kenromaine2387]

Your portable ADDS terminal has the same 3 main PCBs and keyboard as the ADDS 580 used in first Warrex CPU4 systems. The one with the side connector is the FE card ( has the RS-232 I/O logic ) the middle card is the screen memory display buffer ( the display buffer has 9 shift-reg IC's, 1-3 for first 8 lines, 4-6 for the second 8 lines and 7-9 the last 8 lines = 24 lines x 80 columns ). The two main issues are the FE card RS-232 I/O chips SN75188 & SN75189 and on the screen buffer card the 9 memory shift-reg. chip house 2 bits each by 80 positions on the display. The normal test for bad shift-reg chip is to type in 1/2 dup. A B D H P (return) in all 24 lines on the display. A B D H P will turn on a single bit on the ASCII code of the up-case only ASCII display. Many times the A B D H P typed will be displayed as with a extra or missing bit so the A B D H P displays the wrong letters.

[@highpath4776]

would the Envoy work on the centurion(or is it beyond 24x80 ability?) ( your other comment notes the probable failure for the chips - try a card swap between terminals first ?) Presumably CRT in the rat one is power supply related and solvable ?

[@russellhltn1396]

It's not unusual for the RS driver chips to get blown out. All it takes is some kind of surge on the RS-232 line when it's run a long distance.

[@kenromaine2387]

@@highpath4776 The ADDS Envoy will work with the Centurion system(s). The ADDS Envoy terminal is a re-packing of the ADDS 520 & ADDS-580 that we used at Warrex (Centurion) in the mid 1970s on the CPU4 system.

[@kenromaine2387]

@@russellhltn1396 Correct the RS-232 lin driver & recv. IC like the SN75188 & SN75189 ( or 14188 & 14189 ) failed often after lightning storms within miles of the computer system. The long RS-232 cable from the computer to the terminal acts like an antenna when lighting is in the area and blowout the RS-232 I/O ICs on the terminal ( and also the Centurion 4-Port MUX card ).

[@n2nby]

Good luck finding the Static shift register chips. It was the reason ADDS stopped production of several lines (580/880/980/620) Then the regent series was produced followed by viewpoint. The video memory card is sectioned by 3 groups of 8. abdhp is only need once per section not all lines. Check test key -L clear screen abdhp -K K abdhp -K W abdhp . re: ctrl is control key, space is space bar. The space is important. Any bad shift registers will show as a @ sign. FYI -K was direct line access @ line 1, W line 24

[@GeoffSeeley]

Little did you know the RS-232 was the number of Rat S**** in the chassis.

[@UsagiElectric]

Speaking the truth over here!

[@HappyBeezerStudios]

Sadly the computer doesn't support CAT-5, because it would surely need some to get rid of the rats. But at least the rats keep hardware bug from creeping up.

[@CrystalStarscape]

lol rat shit 232

[@Hunter-is-gay-af]

i love this 🤣

[@laser31415]

I love Simple Green. No angry keyboard tapping here. I love watching your restoration videos. I live the dream through your channel.

[@UsagiElectric]

Thank you so much!

[@Oogobuk]

Usagi !!! Where Electronics, Software, and the Black Plague all meet...

[@UsagiElectric]

You never know what you'll get on the Usagi Electric channel. Vacuum Tube computers? Insanely loud printers? The Last of Us? Everything is on the table!

[@chesthairascot3743]

To add one nugget to the cleaning bit- It's a good idea to be careful with wire harnesses in addition. Water can wick several feet inside the wire insulation and can stay there. This can cause issues in the long-term on some wire types. It might also be a good idea to hose the boards off with distilled or de-ionized water as a final wash so that it doesn't deposit minerals on the boards during drying.

[@raybarker]

"A switch here that says 'modem' underneath it - I have no clue what that does." Pretty likely it selects between the acoustic coupler and the data port. It's not clear if this was actually set correctly through the serial experimentation. I also suspect the rear BNC is for connecting an adult-sized display. I'm actually surprised more of the protocol controls aren't on the front panel, given it's a luggable terminal for working in the field.

[@iroll]

I was silently screaming this at 25:44 when he tried jumpering the pins on the serial port! 😱

[@imark7777777]

Thinking the same thing for the BNC Jack. Otherwise I can't make sense of it. The number of things that video output is not a standard on when it has a built-in display is so annoying. oh and @iroll you're right I hit the timestamp and immediately went AAAAARrrrrrrrrrrrrrrrrr.

[@antronargaiv3283]

"Modem" position enables the acoustic coupler and built-in 103-type modem (good to 300 baud). The "up" position routes the data path to the RS-232 subD connector and allows you to use the faster baud rates for direct connection to your computer (or a faster modem)

[@vicenary]

To get the keyboard loopback working, you might have to assert DCD to the terminal; on the VT52-like terminals I used, you could loop DTR back to DCD; on those terminals, DTR was an output that would be asserted when the terminal was "online". We would also wire those two to the DSR pin. You may also have to loop back CTS to RTS if the terminal requires a hardware handshake.

[@salan3]

When I worked for Tektronix we washed 99% of stuff coming in for repair. Then it spent a couple (or more) of days in a drying oven. sorted a lot of problems out and made many look like new. standard procedure.

[@petermikus2363]

Heard about that, it probably really is the best way to clean this stuff.

[@DefaultFlame]

It's how I always clean my keyboards. Slightly soapy warm water, a good scrub and rinse, and then let it thoroughly dry (no drying oven so I usually let it dry out for a week) before putting power into it again.

[@arcanescroll]

People that complain about washing boards have never worked in PCBA manufacturing. We run assembled boards through plain water washes every single time, it's how they are cleaned before configuration and testing. Heck, I literally spent over an hour washing boards just a couple days ago at work. Although, personally, if the board can handle it, I just bake them. Not only does it dry them out more thoroughly, if I do have to do any touch up soldering it makes that go so much better as well.

[@bzuidgeest]

I doubt you use tap water though. So much (natural) contaminants in that I wouldn't buy from you. But for this videos purpose it was fine.

[@arcanescroll]

@@bzuidgeest It's literally just Deionized water, a.k.a. purified water. And we manufacture for some of the biggest companies, including stuff in your computer, so you kinda already do. Also, if you travel by plane then I hope you don't mind :)

[@kenromaine2387]

All the Warrex / Centurion minicomputer PCBs had the solder flex remove during mfg by a trip to the Sears dishwasher for a wash cycle (without any heat dry cycle). The PCB air dry in a rack for two day the moved to a heated burn-in rack with all DC voltages ( +5, +12,-12 ) for 48 hours for being tech-ed and installed in to a Centurion system. We even ran field repair returns in the Sears dishwashers as needed. Yes the Sears dishwasher was purchased at the local Sears store in the mall.

[@dennisp.2147]

Came here to say it , but you beat me to it. People who object to washing PCBs have never worked in a large-scale manufacturing environment.

[@arcanescroll]

@@kenromaine2387 I have used my dishwasher so often over the years for PCBAs. Sometimes it's just easier than cleaning them by hand.

[@adslf874yti3q7u4hf83]

I saw the title and yet I still chose to watch this during breakfast. Thats on me.

[@UsagiElectric]

Can't say I didn't warn you ;P

[@TheOriginalDoctorG]

Didn't feel like too drastic a shift of gears to us -- with the goal of getting a nice portable terminal, it's all part of the same project, and we can enjoy the process of discovery/realization right along with you! I have a feeling the "smelly" machine will prove more useful in future diagnostic efforts now that it is clean as well.

[@MayaPosch]

Yeah, I don't see cleaning the now-parts-machine as a 'shift in gears'. You rather expect twists and turns with projects like these, all the while holding out hope that the 'parts machine' may get a fresh keyboard one day too :)

[@Wadethewallaby2001]

5:31 the modem is designed to communicate with a telephone line such as your landline back in the day there weren’t no ethernet before ethernet we used landline. The modem will connect to your computer. The modem is a device I connect to your router, which is the device that emits Wi-Fi wireless communication for your electronics that are not wired in using an ethernet cord the modem gathers up analog signal and transforms it into digital. The digital signal is what we use but back in the day the modem will transfer the analog into an actual readable system. Then all you had to do was login beeps and noises would make it login each these noises represents a “phone call to the modem you’re basically calling to find the Internet, which takes you to the Internet. -This information is from the Wallaby mob website.

[@srenhaandbk7904]

"I've spent the last day and a half swimming in rat excrement and I didn't need to" Brave guy did it anyway, what a champ

[@SeekingTheLoveThatGodMeans7648]

The rat machine might not be permanently out of the picture. Would it be possible to sub the CRT module from the clean machine into the rat machine? If only to give the rat machine a second chance to show something? In order to better deodorize the rat machine parts, perhaps a dunk of each board for a few hours in some Nature's Miracle or equivalent enzyme/bacterial product from a pet store might be helpful. An emanation of especially pungent ammonia odor is good news here, for it means the waste is breaking down, releasing its nitrogen. (Sometimes a situation has to stink worse before it ceases stinking.)

[@UsagiElectric]

"We do these things not because they are easy, but because I'm a little dumb." - John F Usagi.

[@minty_Joe]

Ah, a day in the life for shango066, too.

[@Graham_Rule]

25:46 the Modem switch is down so I'd expect the system is looking for data from the acoustic coupler. I can't make out the switch in later clips.

[@kerryedavis]

The "carrier" light would be for the acoustic coupler. Remember how, in the days of dialup connections, if the connection dropped you'd get a "NO CARRIER" message?

[@UsagiElectric]

Ah! I totally didn't think about that, but makes perfect sense!

[@kerryedavis]

@@UsagiElectric as mentioned in some other comments I have an Otrona Attache portable computer that is about the same overall size as the ADDS terminal but I think the crt is larger and it has two 5.25" floppy drives. But no built-in acoustic coupler/modem. It could even run from battery using a separate power pack thing. I've never seen the power pack. In the early 80s I did some programming for building energy audit software at a place that was selling it to utility companies after a federal mandate required them. They were marketing it with either Compaq Portables or the more compact Otrona. The "base" Otrona ran cp/m on a z80 but most wound up being sold with a PC compatibility card that ran a slightly modified DOS 2.1 on an 8088 or 8086.

[@Sven_Dongle]

All amplitude modulated signals share the use of a modulated carrier wave whose amplitude is, well, modulated.

[@slightlyevolved]

6:15 Mouse. That's mouse poop. Rat poop is a LOT bigger. About the size of your pinky fingertip. Source: I have pet rats. Not particularly relevant, but rats and mice behave differently, plus you really can't underestimate the size difference. Rats are absolutely MASSIVE compared to mice.

[@ct6502c]

Domesticated rats actually make really good pets. They're very intelligent and friendly. I had a pet rat a long time ago, and it was amazing how friendly he was. He loved to climb up on my shoulder and eat sunflower seeds lol. He loved to be held and petted too, and one time he even fell asleep in my hand!

[@paulcohen1555]

Sounds like an expert!

[@UsagiElectric]

You're totally right, I don't think a rat could have comfortably fit inside of this thing anyways. I've seen a few proper rats in NYC, and you're right, they're massive!

[@slightlyevolved]

@@ct6502c Mine like to come sleep with me on the couch, and two of my girls like to sleep in the blankets with me. One was an escape artist and would open the cage door at 4am to come find me and crawl into bed with me. They aren't called pocket puppies for no good reason.

[@paulcohen1555]

The retro computer forum transformed into a zoology class 😅

[@VincentGroenewold]

The terminal colors though... man they are awesome. Usually I'm not a fan of the 70's color wise, but they hit the nail on the head with this one.

[@tom23rd]

Might think about getting an ultrasound cleaner. No complaints on your well reasoned cleaning method though. I imagine that thing when it heats up is going to "share the joy" for a while till it burns off completely 😅

[@jclosed2516]

Yep - Ultrasonic cleaning would do a lot. A lot of people, myself included, use it a lot to clean up contaminated (battery leak, fluid spill) and/or corroded circuit boards. Keep in mind that older electronic parts can be dried out and cracked over time, so that can be a problem. They should be replaced anyway, but thorough inspection and checking is always needed.

[@hoverbeaver]

I restore pinball machines and also have a lot of nasty boards and electromechanical parts to clean up. I suggest getting yourself a 10-22L ultrasonic cleaner (they're surprisingly inexpensive) for future projects. A 50/50 mix of Mean Green and water does great. Next, a quick rinse under the tap and then the air compressor to blow out any water. Lastly: this works great for coils and transformers too! After their bath, they sit in a tupperware container full of silica gel beads for a few days. Overall, it's much gentler than using a brush, and the ultrasonic gets to every last nook and cranny. I've had many crusty barn find come out of the cleaner looking like it rolled off the assembly line.

[@zdeyn]

The PooDeePee 11 Terminal

[@UsagiElectric]

I'm not sure DEC would be happy with our new naming scheme, lol.

[@josephaltman460]

Man, your channel never ceases to AMAZE me! Not just a 70's portable but 1972! Not only is it ancient but it features a modem, a 9600 baud modem!!! Waaaaay ahead of it's time!

[@JanBruunAndersen]

No, that modem will never do 9600. On a good day it will do 300 baud. The 9600 setting is for bypassing the modem and go directly through the serial port in the middle.

[@kenromaine2387]

The internal acoustic coupled MODEM only works at 110 BAUD or 300 BAUD. For the other support speeds you have to use the RS-232 connection on the DB-25 connector and set the switches to match the BAUD rate you need.

[@robertbauer6723]

I was a little surprised that with all the rodent activity, none of the wires or components were chewed. Thanks for a great video!

[@horusfalcon]

This has to be the most psychedelic portable terminal I've ever seen (and I've been messing with computers since the late seventies). Good job using all your available resources. I look forward to the part two.

[@HobbyHalloween]

70's Colors... You know what... Looking at that color scheme today brings back nostalgia, it was swapped out so quickly in the 80's that we didn't have long enough to really get tired of it... and funny as that sounds... I kind of miss it! Thanks for showing us this wonderful 70's tech in all it's glory. Oh how I miss the 70's I didn't get into programming until 77 or 78, but I've seen this tech around and marveled at it... now I miss it. Except for the Rat poo, YUCK!!! But I bet it has its own particular smell that is pretty awesome too. The smell of history! The Museum in Mountain View, CA... when you walk in and all those old machines are there... it's just whatever it is about those old machines.

[@highpath4776]

I had kitchen in orange, sofa and chairs in orange black and brown and diff pattern same for wallpaper

[@HobbyHalloween]

@@highpath4776 remember the avocado green appliances... or those counter tops? There are just things in life that you can't un-see LOL... Well, the retro look is now coming back... How interesting!

[@andygozzo72]

hope you checked the voltages on the second machine? that picture came up suspiciously fast, if its getting too many volts it'd cause that, check crt heater volts , these sort of tubes are usually 10 to 11 v

[@axelBr1]

Usagi's Logic, a derivative of "If it jams force it, if it breaks it needed replacing anyway."

[@2009dudeman]

I like when he does that. My take for a long time has been, "it's already broken, whats the worst that will happen? It will be broken when i'm done?". Funny enough, things get fixed faster that way because you don't waste time thinking about something 2x longer than you need to because of fear of breaking it.

[@jnharton]

I doubt he would do that if he seriously expected anything to explode.

[@UsagiElectric]

Sometimes, you just gotta send it!

[@maartendeen8404]

It's just Schrödingers cat. Until you try, it's both dead and alive, and only trying it out will show you which is true.

[@greenaum]

@@2009dudeman That's my personal tech-support guarantee. "It won't be any *more* broken after I have a go at it!"

[@szapcsika]

You can absolutely wash electronics. I've seen Tektronix and Fluke service manuals, where they discuss how to clean boards with water and detergent. Some Tek scopes have water sensitive components and they are labelled as such with the instruction of removing them before hosing down the device. SO you are 100% right with wahsing the grossness off.

[@SeanBZA]

PCB assembly houses often will use what is essentially a dishwasher, just with no boil cycle, and drip dry, and regular dishwashing powder, to clean new boards after assembly. Big volumes they have a big machine, but small runs just a regular dishwasher is often used.

[@seth8629]

Why does water kill phones then? IDGI

[@2009dudeman]

@@seth8629 Because the phone has a charged battery in it. Take the battery out, and remove water sensitive components (speaker, things that use water soluble glue, etc.) and it can be hosed down. The damage comes from having electricity pass through contaminated water, causing electrolysis and rapid corrosion. No electricity, no electrolysis or rapid corrosion even when using contaminated water that is conductive. In college as an experiment we tried submersion cooling computers to see the effects it had on cooling efficiency. Essentially to see if it could be more cost efficient and environmentally friendly to passively liquid cool computers, instead of using fans or pumps to air/liquid cool them. Turns out, no, the best form of cooling is actually just an air cooler on a big a** radiator. Guess we came to the same conclusion people did a long time ago. But, for our experiment we essentially just took a big plastic storage tub, filled it with various liquids (we used distilled water, vegetable oil, motor oil (used it in our cars afterwards), mineral oil, we even tried a couple types of alcohols courtesy of the chemical engineering department (cleaning or solvent based, not the drinking kind). Distilled water didn't cause an issue as long as we rinsed and dried the boards first, we actually tested the water throughout the test to make sure it was free of contaminates that would make it conductive so we didn't damage the boards. The only things that actually damaged the boards was the solvents, they must have eaten away at several components on the board, and we expected this. Water and the various oils however caused no damage to the board.

[@Adam_Lyskawa]

I worked in a TV repair shop for a while. They taught me to always wash the high voltage transformer when replacing the usual parts. We used a water with a dish washing soap. Then it was dried with a blow dryer and that was it. Why shouldn't it work? It had to. However, I recovered some phones that were sleeping with fish for a while (battery on). I think the tons of rust and electrolysis products were harder to clean up than just some rat poo. It was really, really surprising the phones started to work. I was almost confident that you can just wash electronics and it would work. But well, there was that one lousy rubber dome keyboard. After washing and drying it became absolutely dead.

[@nonadabove]

@@seth8629 Partially because the phone has a live battery with a charge in it, while the disconnected circuit boards do not, and were given a proper drying before power was applied. Water and powered circuitry do not mix because it causes electrical shorts, since the water is conductive.

[@WC0125]

Excellent series. I haven't seen an Adds Envoy in decades. They were nearly a decade old and being sold for nearly scrap prices in the early 1980's when we were still using one. It was a much better solution than other portable terminal we had, a the TI Silent 700, for portable work in the field. I can't wait to see your whole portable built out. WOW!

[@reasonablebeing5392]

Silent 700 with magnetic bubble memory was an absolute BEAST. I went through a lot of thermal paper.

[@sebastian19745]

The problem with washing electronic boards is not the washing itself. As you said, if water enter in an electronic component, it is already dead. The problem is drying and the quality of the water used to wash. If the water have salts in it (hard water I believe is called), when evaporate, it leave those salts (calcium salts) on the pcb, and when the air is humid, those salts became conductive and can ruin or make the electronics to behave erratically. Another potential danger is to leave the pcb too much to dry itself when there are exposed copper traces, the salts contained in the water can start to chemically react with the copper and corrode the traces; the process is accelerated by humidity and salts in the air (if near the sea) and continue even after the machine is put together. I always use distilled water and alcohool to displace the water at the end. I live near the sea and I saw many electronics corroded by the humid salty air.

[@kote315]

If you can't hear the high-frequency CRT noise, you can use a phone with a software spectrum analyzer. This should work.

[@GodmanchesterGoblin]

You memtioned looping pins 2 and 3, but you normally need more than pins 2 and 3 connected for testing serial terminals. The terminal needs to know that it is connec5ed to something and that it is OK send data, so.... Basic 25 pin RS-232 loop-back... pin 2 to 3 (TXD to RXD), pin 4 to 5 (RTS to CTS), pin 20 to 6 and 8 (DTR to DSR and DCD). If half-duplex is selected, then you would expect to see each character displayed twice, once from the internal loop-back and once from the external. Also, I assume that the modem switch should be Off to use the external serial connection instead of the acoustic coupler.

[@andywlala]

This.

[@The_Conspiracy_Analyst]

You need to get this thing working and set up a host modem on the PDP. Find a payphone and dial in to it with this thing! That would bring back some memories. That was a common method (dumb terminals or more often OLD micros) we used in the early 1990s when.....well lets just say when we didn't want to connect to a host from the house!!!😁😁😁

[@IainShepherd1]

21:17 I couldn’t grok what you were concerned about 😁 - love all your hardware restorations, these pieces included, don’t worry about it 👍

[@imark7777777]

24:36 oh that beautiful CRTs Sound. I believe I'm watching in 480P and as soon as the switch is hit that beautiful glorious high frequency noise somehow was not compressed out of the A/V stream.

[@andygozzo72]

those big caps are almost certainly on the unregulated part of the psu section .

[@MartianTech]

Of course they are. And it scares me that that wasn't obvious to him...

[@SeekingTheLoveThatGodMeans7648]

Tap water ought to be just fine for initial cleaning. I'd suggest to follow up with distilled or reverse osmosis water to remove any possible mineral residue prior to drying.

[@williamsquires3070]

Maybe you could try the terminal with the Centurion? Or a modern laptop. Just to see what problems are specific to the terminal and not to the PDP.

[@garyclouse7234]

I once owned a PDP11. Also, I was the resident expert at RSX-11M. My word! So long ago!

[@terryraymond7984]

I have seen other people use water to clean PCB's and Motherboards, I totally agree with your cleaning method

[@larryk731]

That terminal reaks mid 1970s - should get alot of attention at Vintage computer festivals. Love it

[@jackhack1972]

Ya ! Rabbits !!! I had a old terminal and it was at 9600 as well as apple and so much fun . Used the the cooling fan for a bass guitar amp in the end . Love ya brother from Fargo ND

[@pe1dnn]

Loopback of RS232 not only needs TX connected to RX but also DSR, DTR and DCD (Data Set Ready, Data Terminal Ready and Data Carrier Detect), these are for hardware handshake. Otherwise the sender will not send anything because it thinks the terminal is not ready or the terminal will not sent anything because it thinks the receiver is not ready or there is no connection. If you don't care about hardware flow control then short all three together (one in output, the other two are input). If not using hardware handshake then most likely you need the Xon/Xoff protocol unless the terminal and the computer are always able to process the data in time, although you most likely want to sent control-S and control-Q anyway to pause and resume the output.

[@crunchyplasma1876]

Hardware flow control can also use RTS (Request To Send) and CTS (Clear To Send). So to have the best chance to get loopback on db-25 rs232 you would want to connect 6, 8, and 20 together, 4 to 5, and 2 to 3.

[@russellhltn1396]

Depends on the terminal. A lot of them only need 2,3 & 7. They might have a "bias" to keep the other pins happy if nothing is connected to them.

[@pe1dnn]

Sorry, foggy memory. Should be RTS (Request to send), CTS (Clear to send) and DCD (Data carrier detect). It has been a while since I last made 3 wire RS232 cables...

[@mjdapp]

@@russellhltn1396True, but it couldn't hurt to properly set the handshaking pins. Having DCD active should also light up the Carrier light on the front panel. Also, that modem switch on the side might just be for turning the audio coupler on an off but it could also flip the data inputs to the coupler or force a fixed baud rate as well. Most audio couplers worked at 75, 110 or 300 baud in the late 70s/early 80s in my experience (ignoring the weird 75/1200 split things that came along later for services like Prestel)

[@PlaywithJunk]

The BNC connector on the back is most likely an analog video output for an external bigger monitor. DEC VT220 terminals had that too.

[@jefftobin4034]

Strange to see the 1970s design sensibilities in a piece of vintage electronics. Props to you for restoring this unit. I've restored dozens of vintage stereos and never run into rodent droppings. I would have been wearing a respirator. I'm guessing there was a strong odor as well. Ick.

[@joachim1981]

What a beauty! I'd love to see the acoustic coupler in action. Just imagining how someone would have used this on a business trip from a 70s style hotel room...

[@alexkart9239]

11:08 I would put them in the dishwasher. I've done this before, but the boards were modern, like a board from a wifi router. Worked good for me.

[@godfreypoon5148]

Those "Ball" video display modules with the wire chassis are awesome.

[@DonnyHooterHoot]

Be careful with that "rubber" seal on the hard drive platter cover. Mine failed and turned into liquid. Great video!

[@thirstyCactus]

Dayum. that thing is cursed!! I admire your tenacity, sir.

[@ardentdrops]

Excellent technique; I give it an -A. Try spritzing some isopropanol as a drying agent and that'll make your cleaning a little less risky. The higher the % the faster it will work.

[@Ben-ht5yf]

I used to dry boards in a fan forced kitchen oven at 60°C, worked flawlessly. I haven't found one as stable temperature wise as the one I used to have.

[@Rob2]

Good that you are so persistent... I would long have deciced that an old laptop with a terminal program would be a fine terminal for the PDP11!

[@kylek6922]

I didnt realise that the same Ball company that made jars also made monitors, though with a bit of googling it looks like they stopped about the year I was born lol Always fun to see and learn more about all the old tech that got us to where we are today, thanks David!

[@Ornithopter470]

Did they make monitors, or just CRT tubes?

[@Brian-L]

They did a whole lot more! They had/have a division called Ball Aerospace and have been a defense and NASA contractor since their early days. I’m just down the road from their HQ.

[@TheLemonhawk]

I think that 4 slot card cage fits in a version of DEC's VT100 terminal. I recall using them way back when!

[@jlawrence71]

Made total sense you switched gears. The inserted commentary was good to give us context. You might still be able to get some use of the 'RS' one's cards. We shall see. At least they are clean and preserved for some future purpose maybe. Looking forward to the next one !!

[@RobTheSquire]

Right now there is most likely a family of rats on the phone to the police reporting a stolen toilet.

[@JonMarinello]

Really enjoying this series on the PDP 11. I can’t wait to see the big boy in action someday.

[@movax20h]

Nice. I think you have some later model, because the one you showed from the movie/tv-show, had baud selector on the front as two radio / gans switches for 110 and 300 selection. Your has a known in the side door.

[@Kyle-xv5kv]

Completely off topic for the video, But I'm in love with that Honda Beat in the background at around 7 mins in, was a nice surprise!

[@pjcnet]

Well done so far, a good title too since it didn't give away any spoilers as to whether you succeeded or not making watching the video more exciting.

[@rvenden]

I love your troubleshooting work! Your forensic skills are remarkable. Love all your videos.

[@thudtheace]

I still have a couple of ST-225 MFM drives laying around. I need to get an old box up to use them, just to hear the sweet noise of an old drive.

[@bradnelson3595]

Well, now you have a spare parts machine with an aroma. :) I think you mentioned that you have an ultrasonic cleaner but not a large one, and that could help to really sanitize those parts. Might I suggest setting up some kind of fund-a-large-ultrasonic-cleaner button or page. I would contribute to that.

[@KaitenKenbu]

Right before the full send, very thrilling.

[@KallePihlajasaari]

The open trim pots are the biggest reliability issue. The Aquadag coating on the tube looks a little compromised, for reliable correct operation of the tube I would get a small amount and repair the coating looking at where it was before. Keep away from the HV terminal. The other unit might be safer to restore. The low baud rates are probably for the acoustic coupler. The higher bit rates were only offered by the RS-232.

[@timc3600]

David, you need a large ultrasonic cleaner and an active load such as the ITECH IT8511A, both are really useful in the home lab. Re the console, try adding the hardware handshake pins too. link 4 and 5 RTS-> CTS, then 6+8+20, these are other handshake pins DSR, DCD, DTR respectively. Would also be handy to test all the bits from the remaining parts machine once things are working, so you know what is good / bad / needs fixing. Its always easier when you have 2 or more board to diagnose from.

[@crossbow1203]

Your picture of the Digital brand computer brought back a memory I had forgotten. In 1995 I got a job selling pc's at Sun tv and electronics, long gone now but think Best Buy. We sold several brands of pc's and one of the better ones was the Digital brand. One day we get in a new shippment and we put 2 out on display. About 2 hours later we look over and the damn speakers were on fire on the first one. We get them unplugged and about that time computer two's speakers are smoking. Took them all down, back in the boxes with the charred speakers! don't know what happened but Digital disappeared from the store!

[@richb419]

Hi, I've been washing electronics with dish soap and water for 40+ years I usually rinse with distilled water and let dry, very few problems. I think a light bulb series tester is in order in case a short circuit exists in the unit. Rich

[@SixOThree]

It's pretty clear where the Commodore SX-64 got its idea from. The keyboard in the cover, monitor on the left, handle turning into a stand, are all the same elements in both systems.

[@markpruden1957]

St225 wow that bring back memories, think it was first hard drive I owned, in a PC, in the 90’s, had an RLL card that formatted it to 30mb, rather standard 20

[@InssiAjaton]

A few thoughts… You already have a TEK guy’s mention of them regularly washing instruments that came in, before doing anything else. I recall an old news brief or something, where the washing was mentioned as happening in a domestic dish washer. The other hint I like to give is that the odd, high voltages you noticed quite likely were “raw” voltages before respective voltage regulators. Otherwise, best luck with your present challenge!

[@user-nd8zh3ir7v]

Wow that was a pleasant surprise, I assumed the parts machine was in worse shape and or stripped of parts. really did not think you would be able to save the first one, now its looking like you will at least get one going. great video as always!

[@hotsauce2446]

Make sure the brightness is down all the way if you're powering up a crt without the yoke hooked up. It will burn a hole in the center of the phosphorus in a second.

[@geneirwin645]

Hey, you want half duplex for local echo, full duplex is for the chars to go to the computer, then the computer sends them back. For a test without a computer bridge pins 2 to 3, 4 to 5, and 6 to 8 and 20. See if that works. I did serial cabing on S100 systems and a pdp-11/70 and alpha micro.

[@EsotericArctos]

Water and a non-acidic/non-alkaline cleaning solution is actually used professionally for cleaning, so anyone who did do the angry keyboard thing needs to research. You'd let it dry and then do a bath with Isopropyl to just make sure all the water was expelled, but air drying is also a legitimate drying method for PCB's and electronics. Done it many times myself as many professional and DIY restorers have done. Most rodent residue is water soluable and it is the best way to get rid of it

[@humidbeing]

I use simple green to clean old PCBs, too. It works well, is non-toxic, and easy to find. I use simple green in my ultrasonic cleaner too. Only thing to look out for is it doesn't play nice with aluminum. Quick scrubs are no problem, but I've had it cause bad pitting on electrolytic caps I've left soaking and forgot about for days.

[@meltdown03]

Very cool looking device. So retro! Another terminal option would be an HP 4957A. Smaller, but not actually a terminal. It's a serial protocol analyzer, so the keyboard isn't the most ergonomic.

[@jeromethiel4323]

Holy cow! The lowest baud rate i ever knew about for terminals/TTY's was 300. Never even knew 110 was possible. Perhaps needed for the acoustic coupler.

[@Daveyk021]

Wow, I hope you show up at VCF East, but I do understand that is too long of a drive for you, especially toting all that stuff. It was great seeing you there last year.

[@Daveyk021]

I found out the answer is "no". The displayers list is full and registration is close. You were not on their list this year.

[@highpath4776]

@@Daveyk021 plenty of other shows and show and tells to be done. Presumably awaiting rest of Centurion build and the Bendix for the computer museum to be put to bed first

[@UsagiElectric]

I am very much so attending this year! I just won't be displaying anything. Last year was epic fun, but I didn't actually get a chance to see the show. So this year, I wanted to make sure I got a chance to go around and see and talk to the other exhibitors!

[@highpath4776]

@@UsagiElectric And how much will you come back with ( or consign to FedEx ..!) ( remote access to the centurion sorted from the hotel room at all ?)

[@dorcom]

A perfect way to clean is, besides using a mild detergent, distilled water as it is mineral free and thus non conductive. A 100% dry out is to set and oven to its lowest temperature i.e. "warm" (pre check the oven with a thermometer) to fine adjust, leave the door slightly or fully open. At a temperature of around 125-150F and a small fan blowing air inside, place the cleaned item to be dried inside for a few hours. Any water residuals will have evaporated! Worked wonders for me! Dried out any device including Mobile phones! Thereafter spraying/soaking all in Water Disbursement Formula 40, widely know as WD40, does wonders!

[@KAPTKipper]

You can use a Spectrum Analyzer on a Phone to "hear" the 15khz CRT sound,

[@kensmith5694]

Its closer to 16KHz but yes

[@retrocore64]

That looks amazing. Now I want one. BTW, it was great to chat with you.

[@Faselbob]

Those keycaps are gorgeous. I really want a keyboard with that color scheme now. Your editing monitor sure seemed wobbly btw.

[@the_kombinator]

10:15 - Years after restoring my classic (almost fully apparently) , I had a mild poop and pee smell especially on hot days. I had removed and power-washed the entire interior and carpet and it was still there. Last fall while swapping out the interior for a much better gray on gray, I decided at least to remove the headliner, as it was pretty chewed up from storage and just age. As I was removing it, yeah, well, I found the source of the smell. In the headliner, the mouses lived. I removed it with a mask on and luckily the rest of my interior was out so the car got a vacuumed floorboard and a bleach treatment, and nary a hantavirus for me ;)

[@maximcoppieters]

It kinda reminds me of the Commodore SX64 in terms of case design. Cool stuff!

[@greenaum]

Is bridging pins 2 and 3 enough, or should you be connecting RTS / CTS and all that? A proper dummy plug. Maybe connect the terminal to a PC so you've got decent control of the other end. That coax plug at the back looks like a BNC, and I'd guess it's an external monitor socket. The fact that the top of the terminal is flat also hints at that, that you'd use an external monitor back in the office. You could check if it connects near the video generator internally. It's not like the terminal would be put in a cupboard when you're not travelling, it was expensive! So you'll likely have been using it at the office too, with a proper monitor. Probably just standard composite video. Really want to see this thing working, keep it up!

[@garrytuohy9267]

That is the most beautiful keyboard I have ever seen. If I had such a keyboard it would probably forget to eat or sleep and just keep coding until I drop. I can remember the Gold Key on DEC Terminals, but this is completely decadent.

[@aelitadelarobia]

my guess is the slow baud rate limitation you feared it has applied to the acoustic coupler, those I hear were severely limited because of noise

[@rickhole]

The acoustic coupler uses a pulse of two different aurio frquencies, which are limited by the phone lines, as I remember not much over 2 KHz would survive. The bit rate of the signal could not be more than a fraction of the lower of the two tone frequencies, so 300 baud was about tops usable.

[@ahbushnell1]

I assume you know the modem switch is for the acoustic coupler and the other position would be for the RS-232. Good luck! I used your blue terminal with an HP2100 computer when I was in school. It replaced a teletype machine.

[@jeromethiel4323]

Having been covered in poop, i can say definitively, it's a fixable problem. I used to work on a pig farm mucking out the "poop." My mother made me hang my work clothes outside, and take a "hose shower" before i was able to come inside. And then take a real shower before i could sit at the dinner table. Worst job i ever had, but hey, it was spending money in high school. ^-^ BTW, the pigs were awesome. The poop, not so much.

[@nasasts51]

i have formatted an ST-225 for use on a pdp11 but i had to move the jumper and I use a microVAX 2000 (vaxserver 2000) to format it. I have an extra microvax 2000 if you want to trade. (memphis tn). As for a portable terminal, I use an old Thinkpad[750] with DOS and a terminal program.

[@Wayne_Mather]

sitting here 6 weeks into a prolapsed disc (L5/S1) and watching how he put that heavy thing on the bench made me feel my injury all over again! 😎😎🤣🤣

[@andydelle4509]

The large capacitors in a linear power supply are most always pre-regulation. So those voltages you got are fine. The 13v regulates down to +5 and the +/-27v regulates down to +/-12v. They will also go down when the supply is loaded but you can see the headroom built into that power supply. I should also mention that the large capacitor in a line operated switch mode power supply is more or less tied to the AC line. So don't attach any test equipment without using an isolation transformer.

[@paulstaf]

You should get one of those ozone generator machines you could put it in a large box or closet with smelly items and let it clear out the odors... Or use it in your room there to get rid of old musty machine odors. I use it in my garage to get rid of oil/fuel smells, and in my house after cooking. You can't be in the room when it is running though... I usually run it for an hour when I leave for work in the morning.

[@the_kombinator]

12:12 - Anyone complaining about washing the boards is probably not aware of the fact that to ruin electronics with water, they have to have power flowing through them. I knew this at 13, and I bet my friend $20 (that's like $40 now) that I bet this 286 motherboard that I got from school (legally - no case or anything, just the board) will survive a plunge in the bath. I showed it to him POSTing using my 386's video card and keyboard to go into the BIOS and do stuff. Then I took all of it apart, and proceeded to dunk it in a bathtub with 2-3 inches of water in it. 20 mins later I took it out, and I said to my friend to come back in a couple days. I immediately removed all the chips (this was an old sucker, lots of discrete chips) including the CPU and dried those separately. I put it all back together, got my buddy to come by, and (I tested it previously lol) it POSTed and the keyboard worked, onboard RAM (like, 10 DIP modules), everything was fine. Bollocks to the commenters who think this is a bad idea. I've since put motherboards in dishwashers to get grime off them. Just let it dry.

[@the123king]

With the ST225, it might be worth getting an RX33 5.25" drive as it can use the same controller card