I actually got something working on the TRS-80 Model II!

Part of me felt like the left-for-dead TRS-80 Model II was a lost cause -- but in this video I actually make a little progress and get one subsystem working.
Part 1: • Another left for dead ...
Part 2: This video!
Part 3a: • This is how to use an ... (using 8" drives on a PC)
Part 3b: • This is how floppy dri... (all about termination)
Part 4: • I'm really scared to t...
Part 5: • I fixed the TRS-80 Mod...
Part 6: • How to fix a Keytronic...
Part 7: • Using an $25 Gotek flo...
--- Video Links
Adrian's Digital Basement ][ (Second Channel)
/ @adriansdigitalbasement2
Support the channel on Patreon:
/ adriansdigitalbasement
-- Tools
Deoxit D5:
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O-Ring Pick Set: (I use these to lift chips off boards)
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Elenco Electronics LP-560 Logic Probe:
amzn.to/2VrT5lW
Hakko FR301 Desoldering Iron:
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Rigol DS1054Z Four Channel Oscilloscope:
www.rigolna.co...
Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier:
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TL866II Plus Chip Tester and EPROM programmer: (The MiniPro)
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TS100 Soldering Iron:
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EEVBlog 121GW Multimeter:
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DSLogic Basic Logic Analyzer:
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Magnetic Screw Holder:
amzn.to/3b8LOhG
www.harborfrei...
Universal ZIP sockets: (clones, used on my ZIF-64 test machine)
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RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI)
www.retrotink.com/
Plato (Clone) Side Cutters: (order five)
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Heat Sinks:
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Little squeezy bottles: (available elsewhere too)
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--- Links
My GitHub repository:
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Commodore Computer Club / Vancouver, WA - Portland, OR - PDX Commodore Users Group
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--- Instructional videos
My video on damage-free chip removal:
• How to remove chips wi...
--- Music
Intro music and other tracks by:
Nathan Divino
@itsnathandivino

[@ScottPlude]

When I initially found this channel a few weeks ago, I thought "hey neat". Now I am truly blown away by your diagnostic skills. BLOWN. AWAY.

[@catriona_drummond]

that is indeed one of Adrians prime qualities. Once he bites himself into a problem he will not rest until he figured it out.

[@xyberfunk]

1 skill to rule them all = PATIENCE :-)

[@michaelburns8073]

He's far better than you realize. He also debugged the Commander X16 computer. He found the problem that even the two guys that designed it could not. And, IIRC, Adrian said he had no formal training in electronics or electrical engineering. I was hoping he would share his method and journey from zero to hero in learning this stuff when he reached 100k subs, but we haven't gotten it yet. Adrian, maybe a good 2nd channel video would be going into detail your process of troubleshooting.

[@dsnein]

Strongly agreed. The commander X16 fix and Adrians casual modesty around it are absurd.

[@roberternest7289]

Are you a capacitor? (hehehe, pun intended)

[@XAWZ]

Some years ago I came across one of these things for nearly free so I decided to take it, but I've never been confident in playing around with it due to the strangeness of the thing. It doesn't help that there isn't really much of a enthusiast circle surrounding these things. This video series is really helping to demystify the Model II for me. I may take a stab at getting mine working. Thank you Adrian!

[@tbddevelops]

I replaced a Game Gear screen yesterday, first time trying that much soldering and wiring. And it worked. I channeled Adrian as I succeeded "It works!". I never thought I would get so engaged by someone else's success with electronics repair. But, I've binged dozens of videos the last week or so, and I can't wait for the next part of this series.

[@VincentGroenewold]

So nice the engineers are showing the expected graphs! Should be a standard thing almost.

[@dunebasher1971]

It was, back then. I've got numerous service manuals for 70s and 80s TV/video equipment, and they all show the expected waveforms at all the test points.

[@kaitlyn__L]

For so long I had wondered about the Magic in genlock syncing, but when your subtitle about not having an external trigger on the function generator showed up, it made me realise it’s probably similar to signal-triggered waveforms on a synthesiser. Love your syncing by hand by the way :D

[@nickwallette6201]

I was thinking similarly - time to pull out the video toaster! :-)

[@brentadams28]

GenLock is very similar to wordclock. There will be a master timekeeper somewhere. Instead of using an internal sync to work on its own, and perhaps play well with others whilst marching to the beat of its own drum, everything set as a GenLock (or wordclock) slave won’t do anything until it gets the clock from the master timekeeper. In video world, you don’t get any distortion of frames when live switching between cameras. In audio world, it has two different prospects but the same principle.

[@kaitlyn__L]

@@brentadams28 oh, so it’s just a regular old external clock trigger. This entire time I was thinking genlock first locked-on to the master sync from video1, to then apply across the rest of the board with the other sources. (Which is the part I said about reminding me of a signal-triggered function in a modular synth.)

[@brentadams28]

@@kaitlyn__L basically, yes. People started using different names when basic standards per application (and connector) were established. What you’ve described sometimes happens in an ad-hoc type situation, but in a professional environment there is either an external generator or the switcher is master and cameras are always set as slaves. Same thing happens in audio world with digital consoles/amps/snakes.

[@kaitlyn__L]

@@brentadams28 I think I saw it happen “ad-hoc” in a Video Toaster demo and thus thought all genlock worked like that. The irony is I was thinking a master clock would be simpler, but having seen syncing from one VCR to another on the Amiga I thought there must be more behind it. Good to know my instinct was actually correct then. Using the master mixing console as the clock source and setting all the cameras to an external trigger is definitely the kind of thing I’d had in mind years ago. The wishy washy way they explained it in the Toaster demo gave me the wrong impression that you needed something more complex than that to keep everything working together, with clock drift and re-locking on and stuff like that given CRTs’ wider timing tolerances. I’ve known about eg timecode syncing in video production for the longest time, and I’ve known about vsync and hsync in analogue video for the longest time too, but I just wasn’t sure how genlock fitted into it all. So thanks for clarifying!

[@catriona_drummond]

Adrian, I am watching your channel for some time now. And I really think that if you say you are not good at something, it actually means you are not experienced in it. And important difference taht we as your viewers probably sometimes see clearer than you. But it's good that way, because the overly cautious tend to blow up a lot less stuff than the overly confident. Especially when the stuff is old, valuable and getting rarer. It ties it with your thourough, methodical, researched approach to things which satisfies the German that I am on a deep, heartfelt level. I mean, yeah there are adventures and sometimes screwups (like when you broke the ROM for the ultrarare 4-drive-Floppy-controller), but really, in general, it's deeply satisfying to watch how you go about things.

[@AaronBockelie]

Adrian, If you're interested in de-rusting fasteners, take a look at electrolysis baths. it's super easy and relatively safe - a cheap "dumb" 12 volt battery charger, a sacrificial anode (a chunk of carbon steel), some metal wire to loop all the parts you want to remove the rust from, and a plastic tub with washing soda (or even baking soda). Set it up, and let it cook for a day or two and every single piece of rust is stripped from your parts. Make sure you dry and give a protective coating as soon as they're out - they can flash rust quickly. There's quite a few videos and discussion about how to do this, I have done it a lot repairing vehicle parts and tools.

[@jondough76]

I always enjoy your excitement when you get something working. Keep up the great work!

[@willhughes99]

Adrian, what you just did to diagnose the missing signal, and then to generate it and test... I am truly in awe! Great work, and really nicely presented, thank you

[@Carlos_Rodrigo]

It works ! It frikin' works ! Yet another AWESOME repair ! Congratz Adrian 👍🏻

[@gazza8234]

G'day Adrian enjoying the M2 vids. I've had the "pleasure" of repairing a couple of the M2s including painfully manufacturing the pads and restoring the keyboards one key at a time - aaaarrrgh.😣 One gotcha with Aztec supplies is the snubbers. Looks like you dodged the yellow Rifa "nades" but it would still be a good idea to replace them. It might have been good luck but I've found the 8" floppies to be OK after a grease&oil change with one drive having a shorted tantalum which worked perfectly after replacement. The P/S took the short OK. Happy to sit back with a hot cuppa and watch someone else go through it.☕

[@drruncmd]

At 19:01 You mention that huge capacitor at 2035 VOLTS!!! Imagine if that was true, no one would ever open any power supply with that kind of rating!! Lol! I know you meant uF and not voltage but, seems like I am the only one who noticed this?? BUT... Great job Adrian as always! I can never wait until your next videos are released! I prefer the longer videos you create but shorter ones are also good too! I have a BBC Master 128 computer in mint condition and working, but, upon opening the power supply, I broke a component off the power supply board when trying to remove the metal chassis. What a nightmare that was! I don't know what the component was, but it looks like an old style inductor. It is small, round and has several colour bands on it and googling around, I cannot find either pictures of this PSU board or even the correct schematic for the PSU! All I can find are BBC Micro boards and schematics which are completely different to the Master 128!! Do you own a BBC Master 128?? I know you mentioned something about it in a previous video and maybe know what the component is and its value???

[@stevesether]

One suggestion for you, and everyone else for rust removal. Evaporust. It works MUCH better and much faster than vinegar, and it's re-usable many times. It also has the advantage of never removing metal because it makes the rust soluble in water. It's a little expensive, but since you can re-use it, and just dump what's left back into the bottle it's quite affordable. I bought a gallon of the stuff in early 2021 and removed a lot of rust from old tools. I still have likely 3/4 of it left, and I expect that gallon to last many years.

[@BloodBlight]

Two more options that might help out for rust are Evaporust and elecrto rust removal. The Evaporust is great for connectors, screws and other small things that would be difficult to do with electro removal, and is reusable. It is super safe and you can leave stuff in it for days plus to really get into tight stops. Electro can be nice because you can go directly from one tub for removal into another tub to do plating to prevent new rust from forming without having to paint. Say nickel for example. You just need three tubs, removal (water and some salt), final rinsing (distilled water only, use tap first) and plating (vinegar and salt). Just don’t let the part dry or you will get flash rusting (very cool to watch, but no fun). But in ether case, you would need to use a paint remover and a wire brush first to really do a nice job.

[@quincy1048]

It is awesome to see the amount if effort you are putting into something that as you say may never work again. Definitely shows respect for this old hardware.

[@chadhartsees]

Dead bugs, spiders, leaves.. this is a perfect fall project!

[@TheChris4808]

And perfect scene for a horror movie featuring spiders 😅

[@TheChris4808]

And perfect scene for a horror movie featuring spiders 😅

[@CP200S]

Apple cider vinegar overnight is very effective in removing rust. Of course you must remove all connectors before and sink just the rusted metal part in a basin with vinegar.

[@VintageTechFan]

Since the PSU is going to be one of the next steps: If you want to power something mains powered up which you are not to sure about the condition, you can put a classical light bulb in series with the mains connection (60-100W or so, typically, depends a little on the power rating of the device). If something shorts out, this often will prevent further damage, since it limitx the current and the bulb lights up brightly, alerting you to shut off the power. Normally it should only glow dimly. If you combine it with an isolating variac, that's the luxury variant (well no, the one you are technically supposed to use, from a safety standpoint). Admittedly, it can be a little problematic with switched PSUs, and prevent them from starting up correctly, but it will still very likely prevent the big bangs.

[@kirknelson156]

ok on the cap readings, keep in mind all those caps have a tolerance of +/- 10%, so that first one you checked that was supposed to be 470 has a upper limit of 517. you might not think its off by that much but older power supplies very much utilized an RC time constant for regenerative feedback. and of the cap gets too far out of spec it throws off the timing of the pulse and the supply wont work. so to be sure I'd take it out and measure it out of circuit.

[@nickbnash]

Incredible work! This is a really cool series. Thank you for all of your work on it. I can’t wait to see how everything turns out.

[@baspverhoeven]

I'm a regular viewer of your channel. Love it! Regardless the fact that I'm not an Tandy man myself this series is SO VERY interesting to watch. It taps into every aspect of what retro computing is about. Thanks Adrian!!! Great serie and I can't wait to see part 3

[@oldguy9051]

The VirtualBench sure is nice, no doubt about it but also very expensive. Prices start(!) at 2000+ Dollars and used it isn't cheap either. That's an extremely generous donation! I hope we see more of it in the future. There are cheaper solutions, though. The Analog Discovery 2 Pro from Digilent costs "only" about as much as the oscilloscope that Adrian uses (Rigol DS1054Z).

[@Rorschach1024]

if you get the crt board functioning, i would use some electronics grade (NOT building supply grade) silicone to fill the cracked rubber on the flyback. builder grade silicone generates ascetic acid (vinegar) as it cures which is corrosive. electronics grade uses platinum group metal catalyst in it to cure without creating acid in the process.

[@Retrocomputernerd]

This is really cool, I didn’t even realize this Tandy with the 8” floppy existed. It was so cool watching you tap into the CRT drive board, power it externally and drive a signal from a CGA source. This of course could be a controversial statement, but after watching you drive it with the signal generator, I couldn’t help but wonder if that could be done with a Raspberry pi. Maybe some kind of A - B selector switch device could be used to toggle from a raspberry pi to the original Tandy. Then you could do all sorts of things with the Pi connected to that CRT. I love the old CRT AIO computers, keep up the excellent work!

[@smakfu1375]

It's weird, I've never wanted to own a Model II (or any TRS-80), but I really want to see this machine live again as it played an important part in my formative years. We had this machine in my home-room at my school in 1st grade . It was the very first computer I ever got to use regularly (at least a year before I got a Vic20 for my birthday). While any chance to use a computer was exciting, the TRS-80 was on the low-rung of that excitement. The other classrooms had Apple II's, and those had more entertaining education software and had graphics capabilities. But I fondly remember those early days: we even had a textbook that described, in fairly comprehensive terms, how the machine worked (and it was oddly specific to the Model II - perhaps it was provided by Tandy). I learned basic on that machine, keyed in my first program-listing from a magazine. I remember staying late, with our "computer teacher", to debug / port the program, as it had specific problems with the disk loaded "professional' basic interpreter, on the Model II, having a different cursor positioning scheme. I was very lucky, at just 7 years old, to have that opportunity, and my fascination with computers (of all kinds) hasn't waned in all these years. The Model II was there, at the beginning, so I hope you get this one back in working condition.

[@rlgrlg-oh6cc]

Never seen a monitor driven by horizontal from one source and vertical from another. Not sure it would have ever occurred to me to do that! Nice job!

[@eDoc2020]

I've run a TV CRT with the yoke and high voltage on one chassis and the neck on a completely separate chassis. I knew I had to be very careful or else I might end up burning a solid dot in the phosphor.

[@Dukefazon]

3:15 - depending on the overall condition after the jelly you could put masking tape over the text to protect it while spray painting it. But if the rust is so bad that it eats it's way under the text you can't really save it, all you can do is print new labels and hope they will stick. This reminds me, I really wanted to get a nice Brother label maker but the nicer models are a bit too expensive for my taste with all the label options. 17:15 - those pads on the upper-right quadrant don't look nice, around that circular arrangement there are 2x2 quare shaped soldering and one of them is really rust-looking, check that too, please if it has continuity. Wow, that was really exciting! Can't wait for the next part, I hope the PSU is okay now that the flyback has no problem, you should be able to fix it if any fault comes up.

[@Ruskaga]

Someone like Colin Furze could probably cut out a back panel on his plasma cutter and put in the 90-degree bend, but the final product would likely also come with a jet engine, fireworks, or rotating knives to boot.

[@chiblast100x]

On the Brother printer, we have a PT-2730 where I work and it really is just kinda overkill for 99.9999% of use cases. I've been thinking of getting a PT-D600 for at home organization since it has the connect to PC functionality I'd want for printing labels at home, which the $50 to $70 models typically don't, and is $100 rather than the several hundred a 2730 goes for.

[@Dukefazon]

@@chiblast100x I was thinking about getting a PT-P750W or something similar, it's between $125 and $175 plus all the different type of tapes for it. I really like them but yeah, probably a white masking tape with a regular pen will do for now :D

[@catriona_drummond]

Interesting new game: "The need for sync - Tandy drift"

[@lucyinchat]

It's a racing game designed to run on Trash80s

[@BlackGymkhana]

Nice song… Neela was drifting there...

[@EngineeringVignettes]

Hardware on that TRS-80 is likely the standard SEA sizes. Having some pan-head machine screws and nuts assortments is always handy to have around in the following sizes: #4-40, #6-32, #8-32. Less common are the larger ones: #10-24 & 1/4-20" Nice work on jury-rigging another horizontal sync signal for testing. Understanding the needs of the system under test is a valuable skill and I am glad you see you demonstrating that. It's unlikely you will need much of it going forward but if so, you could try adding a pulse stretcher to the CGA card to extend that horizontal sync signal. Not ideal as that will introduce some small delay (ten's of nanoseconds) but then the testing PC can generate all of the signals. I think though that you would be getting the TRS-80 video generator up and running first anyways... I think. Signal upside down... did you plug the yoke back in backwards? I did not see that, just wondering. Both H&V would be flipped... HV Flyback damage - Maybe a good idea to goop some HV silicon compound on that broken area at the top anyways, just to isolate HV and prevent ingress of moisture in future. Running it a bit first should dry the transformer out first. Cheers,

[@emorelama]

"This is a win", and you are a master. One of your best videos. Thank you very much for sharing your discoveries so neatly.

[@jeromethiel4323]

Just another tip, use your DMM to do a resistance check on all electrolytic capacitors (mind the polarity) before powering up the machine. Electrolytics have to be formed to be capacitors, and that forming process reverts if not under charge for long periods of time. Anything more than a year, and you should be cautious. Putting voltage on them via a resistance check, helps to at least partially form the capacitor, so that when you actually power it on, the cap doesn't explode (small ones will just pop or hiss), thus necessitating a replacement and possibly damaging other components.

[@JmanNo42]

You are freaking fantastic Adrian, you have so broad knowledge and and so good understand the nuts and bolts driving things, i got zero electronic skills and recognize your some sort of genius.

[@WC0125]

Adrian, great video. It is not surprising it works. That flyback is silicone dipped and is quite robust. You did a lot of work to see if it works. You could have just injected a horizontal and vertical pulse and cranked up the controls. It would have shown a blank raster. As for the graphics on the monitor, you could get a "High Resolution Graphics" card for the machine for more than B/W video. Some even swapped out the P4 phosphor CRT bulb for a P1 for a green display like the 16/6000 had. We did that to one of our later upgraded IIs. As for the power supply, BE VERY AWARE of the expoxy potted Rifa caps. I'd replace every one before powering it on. They look good, mabye even test good at first but may have cracks in the epoxy and most likely have had moisture intrude. They POOF quite nicely. Exact replacments are available from Digikey or you can use another brand. As for running it without a load, you can repair and test it with no load without an issue. I've repaired a few without incident. On a side note, the power supply for the computer is the same on used in the disk expansion unit (should you ever find one). I look forward to your next installment. Happy Computing and restoring.

[@n.h.s.a.d.m.]

Virtual Bench seems very useful. I'm surprised I've never seen something like that sooner for people who can't afford oscilloscopes, although all the comments here are saying its much more expensive than one.

[@Renville80]

To be honest, that power supply looks like an off the shelf part. It seems Astec is still in business, so maybe they have something that’s fit / form / function compatible if this one conks out. I remembered something else. There are two slightly different sets of frequencies for NTSC TVs. Monochrome is supposed to be 15750 Hz horizontal and 60 Hz vertical, and color is approximately 15734 Hz horizontal and 59.94 Hz vertical, the difference being due to the latter dividing into the 3.58 MHz color frequency.

[@jaycee1980]

Adrian, can you still get incandescent light bulbs in Canada ? Halogen ones will do. If so, it is worth making a "dim bulb tester" for working on any kind of power supply. I always use one when I've serviced a power supply, and it's good insurance against catastrophic failure occurring.

[@eDoc2020]

I'm sure you can still buy some varieties of incandescent bulbs in Canada, but it doesn't really matter. Adrian lives in Oregon. Plus you can find secondhand light bulbs in any part of the world or use substitutes like power resistors or heaters.

[@jaycee1980]

@@eDoc2020 Yes I forgot he lived in Oregon now. It is the PTC behaviour of the bulb filament that is important, which neither a heating element nor a power resistor would do

[@eDoc2020]

@@jaycee1980 I believe heating elements are PTC but likely not as much. Maybe ceramic style heaters would be more suitable. Another idea is using some sort of motor setup. With the motor stopped it can pass a decent amount of current but once it starts it won't need as much.

[@drruncmd]

Yes, this is a linear type of power supply and they do work in a different manner to switch mode supplies. With this supply you have, there shouldn't be a need to attach a load for it to power up. I think, this will power up whatever the load is at the terminals. Switch mode supplies have current and voltage sense circuitry whereas this linear type does not. So, if this is powered up and tested, should output the voltages listed for the output terminals. Again, switch mode supplies will limit the voltage on the output if no load is applied. When a load is attached to the output, the voltage will power up accordingly.

[@berczigabor]

2:45 I'd get a (preferably battery powered) mini-dremel with wire brush attachment(s), that will allow you to clean the rust mechanically off stuff without damaging in-tact metal parts, but still gently and with a decent speed (you don't have to wait days or weeks like with most rust dissolver fluids)

[@ericnelson4540]

When Adrian starts screaming "It's Alive! IT'S ALIVE!!!"

[@greywizard2557]

There really should have been a clap of thunder and a maniacle laugh at that point.

[@fawad.rashid]

It freak'in works ! :D

[@RayBrooks0]

That's what we watch for!

[@madhampster]

Sounds like a mad scientist

[@AerikForager]

From my heart and from my hand why don't people understand my intentions? (Weird) :D

[@derekchristenson5711]

Very nice! I'm so ignorant about which are the high voltage parts of a CRT, I always cringe when I see someone in a video moving the yoke around, LOL. But, now that I've seen the flyback pointed out, I think that's the big, rusty part in my old Amdek monochrome CRT... which still works... so far... 😬 No idea how it was stored before I got it.

[@thedungeondelver]

That information on the input board for the display is fascinating to me. I would have suspected something entirely proprietary, but I guess Tandy didn't wanna reinvent the wheel. Good on them!

[@jeffreyphipps1507]

Wow. It looks like you were hand wiring a Colossus Mark I at Bletchley Park! So many wires! Great job!

[@benjaminramsey4695]

When you were describing all the wire connections for the video signal, I just had a big 'ol grin. That was great. That's the sort of thing I like watching your channel for!

[@ranieriphoto]

It works! It FREAKIN’ Works! Well done Adrian. I can’t wait to see how this ends.

[@tigheklory]

I have washed a ton of monitor chassis and the flybacks were fine. I don't know if that particular flyback is ok to get wet. Also, use cleaner wax on that paint before you use a clay bar.

[@TotoGuy-Original]

meguiars paint cleaner is good

[@tigheklory]

@@TotoGuy-Original yeah that's exactly what I meant. LOL

[@waynesmith6417]

I'm 70 and the TRS modii was new when I played with it. Its really a simple machine. Sockets are most likely going to be a problem. They mostly didn't have gold plating. The power supply may need a load to operate and if you test it without a load it may smoke. Test the caps before you turn it on, they are the most likely bad parts if its set for a few years...decades. It was a 4meg Z80. Some where in the barn I have a Z80 in circuit emulator with an rs232 port called a Nicolette. It had a memory test function and you could read the bios and put data in ram. You have a manual so I"m sure you will prevail. Good luck man.

[@mal2ksc]

Since the CRT is in great shape, you could at the very least make a convincing knock-off of a TRS-80 Model II such that someone would have to look under the hood to know it's a Raspberry Pi or whatever you'd use. So we know this isn't a total loss. If that doesn't appeal to you, maybe make the weirdest looking Mac ever. :)

[@aplund]

Nothing quite like knowing how something should works and having it work as expected.

[@petefish9401]

Oh my, I love these videos. I can't say why as you are way beyond me in most of what you say but still, there's just something compelling about these. Please keep more coming.

[@jme36053]

EvapoRust is your friend where rusty metal parts are found. Once wiped or rinsed off. Brush with wire wheel, remove any oils and then paint with Rustoleum-type product. On screws, after EvapoRust, brush with wire wheel, heat to red hot and drop into food-grade oil. It will darken the screws and prevent further rusting. Don’t wash them in vinegar as it erodes the metal. Vinegar is good for Brass or Copper as it removes p patina. You could further polish the brass/copper fasteners if need be.

[@ObiWanBillKenobi]

Congratulations! This is one heck of a restoration attempt. I dare say your magnum opus so far!

[@jeremiahlyleseditor437]

Amazing you turned the yoke without wearing gloves.

[@jeffymooch]

I swear there needs to be a collab between Adrian's Digital Basement and HandToolRescue to clean up this chassis. At the very least that giant bucket of evaporust might be useful...

[@3vi1J]

Keep fighting the good fight, Adrian. You'll get it working!

[@michaelboldys3330]

After all that effort. Upside down and back to front. So excited. Rossman!

[@notsogreat123]

Navel jelly is phosphoric acid. It is used to prep steel for painting. Use it on the screws and steel panel parts.

[@pauldourish]

Great stuff! The Model II never gets much attention and so it's nice to see this series. When I was a kid I used to hang out at a local Tandy store playing with their machines and while I didn't use the Model II much, the follow-on machine, the Model 16, was one I used a lot -- running Xenix, Microsoft's version of UNIX, of all things.

[@infinitecanadian]

I just thought of suggesting that International Instruments gizmo to my dad...but then I realized that he already has everything, including a spectrum analyzer. Helps to have a lifetime of electronics experience.

[@aaronb7631]

My first computer was a Tandy Color Computer Model I. It was compact and easy to move. I never knew, that Tandy made a bloated Model II, until watching your videos. Nice job fixing up this computer!

[@sergiofagundes1972]

When you need to get rid of rust without a some type of "sand brush" (sandblasting, sand tumbler, etc.) or a steel wire brush you can use Evapo-rust. Use one of these gel paint remover, clear the paint and dip the piece on evapo-rust.

[@coyote_den]

HV bleed resistor was probably added in a revision of that monitor chassis as a spot killer, so you don't get a bright dot burning into the CRT after power off. That is a common problem on monochrome CRTs that don't have an HV bleeder.

[@WalterGreenIII]

There are blocks that are used by restaurants to clean grills. These blocks are very abrasive and would work to clean the rust off the inside of a piece of angle such as what that back is made of you can also clean the outside but it would have course remove a paint or labels.

[@krnlg]

What a great troubleshooting video - Adrian you really are great at this, both the troubleshooting itself and making it into an engaging video!

[@erichkohl9317]

A PC BIOS screen being output on a TRS-80 video tube. Now I've seen everything!

[@martindonlon5894]

Okay, that was really cool. Great idea to use the function generator and I think you showed a phenomenal amount of patience test as much of the board as possible before powering it up.

[@neillthornton1149]

I'm loving the Model II series so far! I also spied a climate sensor (I am assuming Zigbee) stuck over your laundry machines. I guess I shouldn't be surprised that the Basement is also smart. Maybe do a Second Channel video about what you are running for home automation? Nothing fancy, just a down and dirty tour?

[@twocvbloke]

On the positive side,at least you could make a "modern" (as in, something 80s-90s based) computer inside the thing driving the original monitor if the original hardware doesn't work... :P

[@douro20]

If he does get it working I'd like to see CP/M running on it.

[@ethanspaziani1070]

Hey man I just want to say I love all the hard work you put into these videos and the stuff that you do thank you for making content on KZbin for us to watch I and I'm sure many other people appreciate and enjoy it

[@dr_jaymz]

You know, this video was quite useful to me. I have been fiddling with a Cub Microvitec monitor that was left for dead and dare I say much more crusty than the TRS. I followed most of the same steps and had exactly the same concerns - but there comes a moment when you run out of excuses and you have to turn it on. In my case the LOPT was tracking to one of its pins. I didn't let it get toasted and I rewrapped the top insulation with Kapton, PET and some neutral cure silicone and.... I got a frame collapsed picture. So its not completely dead - but its trying.

[@emirh77]

Good as always! Thanks Adrian and greetings from Bosnia.

[@leglessinoz]

I still have a working TRS-80 Model 1 Level 2 laying about on a shelf. I think it might have been one of the last sold here in Australia.

[@UpLateGeek]

Wow, that's so lucky that the analogue board was working fine! There's so many things that could've gone wrong with it, I would've thought for sure it would be bad after so long in such poor conditions. Especially with the flyback transformer looking as bad as it is. Hopefully this bodes well for the power supply too, although those early switching units can be pretty petulant.

[@DanBowkley]

For that rear panel with the connectors...you mentioned you have compressed air, head down to Harbor Freight and pick up one of their little handheld sandblasters, and then go grab a big ol box of baking soda. Blast the part with baking soda, it'll get all the rust and crud off and leave most of the paint.

[@roymerkel8008]

here's hoping that you are able to fully reform this machine, I'm curious to see it in action.

[@retrotechandelectronics]

Heat the screws till they turn red and then drop them in used motor oil. They will turn black and be permanently protected. That rear piece would do well with media blasting and matte black powder coating.

[@Kboyer36]

If you can find someone near by that has one, I would recommend just having those rusted metal parts sand blasted. It helps makes sure you have a nice and clean surface to apply filler and paint to. I had to deal with rust that was sadly more severe than this on the IBM 5170 that I restored last year thanks to it's lithium cell leaking all over everything. While it will never look like it did out of the factory, it's a night and day difference from where it started.

[@ultrametric9317]

Just carefully tape over the labels. When you are done, give everything a matte clear coat of Rusto. Painter's Choice 2x Clear Matte. It will look fine!

[@jmcarp0]

Thanks! I love this machine, good job getting that crt going :)) Can't wait to see the rest, keep it going!

[@MrZeroPage]

Bloody fantastic job - well done Adrian, I salute you !!

[@CaptainNedD]

Great video. Perfect drama. Love it and well done.

[@MikesArcadeMonitorRepair]

The second channel should have been called “Adrian’s Analog Basement.”

[@eduardolarrymarinsilva76]

"Adrian's Analog Attic"

[@kins749]

Really impressive work!

[@parrottm76262]

You needed an insert of your new t-shirt "It freaking works!". Loved this one. Super interesting.

[@verishare]

As usual you demonstrate your amazing trouble shooting skills. Even for viewers like me that are not into TRS-80 this video was informative. Thanks!.

[@rager1969]

Dang, Adrian! You are quite knowledgeable.

[@Arachnoid_of_the_underverse]

With the backplate plus anything else for that, Id suggest Kurust f you have it locally. it can be painted on and turns the rust to a safe oxide and you could stencil the text back on using a sponge to dab white paint through it.

[@Pest789]

That was a heck of a stunt to pull off. Well played.

[@andic6676]

Great work! You might want to change the two electrolytic capacitors in the line driver stage to improve reliability/quicken rise times, and clean that multiconnection plug of any corrosion. Awesome outcome so far!

[@fumthings]

i was wondering if the differences between the 2 makers of the boards, differences in the h sync circuit would explain this behaviour. in any case the vert sync polarity would never work off a plain cga card.

[@fumthings]

actually, i think those are tantalum.

[@fumthings]

after examining the schematics the RCA board is a proper oscillator which is retriggered by the sync pulse, the Motorola board looks simpler and cheaper but does not oscillate on its own. the duty cycle of the expected h sync pulse is actually the oscillator, so the flyback power supply just wont run properly with the narrow pulse and needs closer to a square wave.

[@fumthings]

one final thought. its nice that Adrian has some great tools to test with. a ttl pulse stretcher could be breadboarded to change the h sync to suit, and a ttl inverter could change the v sync to suit. its great that Adrian explores these things so we can think and learn about them.

[@eDoc2020]

@@fumthings Based on the specs I guessed the RCA board would have its own oscillator, so I guessed right. There are pros and cons to each design. The oscillator-less design is cheaper and doesn't require horizontal hold adjustment. On the other having its own the oscillator has the huge advantage of not frying if fed with an improperly timed signal.

[@charlieb9502]

I loved this video so much, I am giving a up vote and letting the ads play out even though I have already watched it as a patron. I do retro computer restoration as a side business and I use a small sand blasting cabinet and I have a small paint booth. Along with a silk screen to reproduce the text and some graphics. I learn new stuff from Adrian almost every video. Especially the last one where he used Oxyclaen to do retro brighting. Good stuff!

[@somewaresim]

Very fun video. Got a buzz when you got the picture up. You’re a wizard Adrian.

[@TooMuchMiddle]

That New test bench thing you used was friggin' awesome!

[@lionelguichard6714]

Adrian, congratulations ! It's amazing to see what you achieved.You gave me the will to restart a few old computer (mainly Commodore ) which are sleeping in my garage, but surely easier than this TRS-80. I am eager to watch next parts !

[@irmadcow93]

i used to play a defender type game on the TRS-80 when i was a wee kid. My first experience with CLI.

[@richardepps8500]

Can't wait to see the next component test video.

[@luked3172]

I actually like the part about the power supply. As a CS student it's nice to see things that are just on the other side of the fence.

[@ropersonline]

At about 16:48, the flyback transformer's solder joint next to the T1 label and closest to its smaller 1 solder joint looks really brown -rusty?- to me, but you went on to say you didn't see any issues there upon inspection of that PCB backside later in the video (after 24:00). So how is that fine? Is it something other than rust that doesn't really come across in the video?

[@eddielegs344]

Hi Adrian You will know, treat that back panel with a wire brush and maybe with sandpaper after tearing it then with cheap paint spray new coat of paint on it it can withstand it again.

[@cablekiller]

Food for thought: Try an impact screwdriver on those rusted screws.

[@Haldrie]

It doesn't appear he's having an issue getting them out, he just needs to clean the rust off and make sure they don't rust so easily in the future.

[@McMidjit]

The level of probe jank on that analogue board testing was shocking and I fucking loved it

[@douro20]

You could try building a couple of circuits on a breadboard to adapt the signal from the CGA card: a one-shot multivibrator to stretch the horizontal sync pulse and an inverter to invert the vertical sync pulse.