Martian Tech

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@alisondenu5317 17 күн бұрын

Was watching your TRS-80 Coco repair series from a couple of years ago, and the model number caught my eye. You have a rarity there, it's one of the ones with an enhanced VDG that has native lowercase characters available. I believe there is a pair of pokes that enables the feature, but I do not know what they are because I have never had one of the 3127B model units.

@MartianTech 17 күн бұрын

They can't be that rare because I've got two of them...

@alisondenu5317 17 күн бұрын

@@MartianTech Well snap! That sounds like trade goods. Yeah, those 6847T1's are pretty much Unobtainium.

@Transcriptor Ай бұрын

use the quad version

@MartianTech Ай бұрын

By "the quad version" I assume you mean the M8043 (DLV11-J) or 3rd-party equivalent. Since I didn't have one of those when this video was made and this video was about making use of available resources, that is not really a practical suggestion. Also, had I needed current loop or modem control, the M8043 would not work - the M8028 (used in the video) and M8017, respectively, support those capabilities.

@8bitsinthebasement 3 ай бұрын

Thanks for this series, I didn't know that a logic analyzer worked quite as it does, how cool is that? Throwing up machine language and showing exactly to what point the system is getting to just before it falls down. But, I imagine that if the Unraveled book didn't exist finding the fault would have been quite a bit more difficult. In any cas well done :)

@saileshchhatpar1934 3 ай бұрын

This is the best meter which Fluke had made. I had been using it since 40 years and now has given-up on me. LCD issues (went to extent of replacing polarizers), Plastic casing breaking-up (high humidity, I guess). RIP now. Current generation DMMs r power hungry and use-and-throw types.

@dmmartindale 3 ай бұрын

I have an 8050A that was AC powered from the factory. C38, C39, and C41 are tantalum caps on my unit. C44 seems to have been eliminated; there just isn't a capacitor in the spot next to C41 where the board layout shows C44. So it appears Fluke themselves switched from electrolytic to tantalum (or vice versa) for those caps during the manufacturing run.

@adrielrowley 4 ай бұрын

Amazing a vintage in-house IC can be replaced, though doubt I could solder surface mount with my condition. Gives one confidence to purchase and repair vintage test equipment. Cheers, Adriel

@TCASAnalytics 4 ай бұрын

What does you unit do? Is it not a variable AC power supply? I need a bench top unit which I can set a constant current (4-6 amps), variable voltage (5-25 V) AC output where I'll introduce a load of ~ 1.5 ohms. Is this what I need? What do I need?

@MartianTech 4 ай бұрын

No, it's not a variable AC power supply. It's used to test (DC) power supplies by presenting a load to them. Sounds like you're looking for an AC current source... Maybe something like the Valhalla 2500E, though I don't think that meets all your specs.

@TCASAnalytics 4 ай бұрын

@@MartianTech @MartianTech Thank you for that, after watching your video I did some Google-Fu and realized what I was looking at. I also appreciate the recommendation, I did find a unit which should work for what I'm trying to do. That being bench test an airfield runway/ taxiway light fixture after working on one. Because it's a constant current high voltage series circuit system, I have to completely lock out/ tag the entire system to just change a bulb, nevermind remove and reinstall an entire fixture. The Constant Current Regulators (CCR) that run these circuits are murderous maniacs and will make sure whoever's body just became part of the circuit causing a drop in current will have no chance of living by jacking the voltage up as high as 5,000VAC to make sure it maintains the designated amperage! That takes a minimum of 45 minutes to do this because of the nature of aviation, and just yesterday I reinstalled one of our LED runway light fixtures I had replaced the power supply PCB on, and it still failed to illuminate. I need a way to avoid all that, and the bench top CCRs available are way too expensive for the rural city who owns the airport to procure.

@werner.x 5 ай бұрын

I'm glad you produced this series. Just bought an IB-1103 off ebay. Hasn't arrived yet. I've previously read about probable issues, which are hard to fix ore maybe even unfixable. So, your repairs may be of some importance.

@RockwellAIM65 6 ай бұрын

Oh this is good 'cept I like the PDP with the purple/orange front cover and all the blinky lights!

@RockwellAIM65 6 ай бұрын

Also what'd be really cool, unless you want the big 68k chip, would be to use a 68332. Motorola made a GREAT credit-card sized 68332 board in 1990. Something like that'd be terrific (and a lot faster I believe). Those early 68000 chips were really lethargic.

@RockwellAIM65 6 ай бұрын

Nice power supplies in the background! Yeah I really didn't like the PGA mingling with the 68000... what I really want is a two-chip solution like maybe a 68k with a formerly pricey Xilinx FPGA part. I think that'd be really cool.

@dicko-200 6 ай бұрын

I need a curve tracer, looking in to the BK

@pajodato5339 6 ай бұрын

Great terminal! Love that green-yellow CRT color. And it has a modem! I would love to own one of those.

@lohikarhu734 6 ай бұрын

I was an FAE for Motorola processors in Western Canada in the 1980's, and for Motorola VMEbus Unix systems before that... I think I even have a couple of MC68709's in my parts box... The 6801, then 6809, then HC11, were great processors to work with, and you could actually talk to a real application engineer, in Austin, when Intel "application engineers" were sales guys, and a *real* AE was only available if you worked for IBM, or Ford, or... I actually have an application manual for the XC6801, from 1978, on one of those coilly-binders, printed in good old Courier, on a daisy-wheel printer, with hand-drawn diagrams for ports and timers and such... Fun days!

@lohikarhu734 6 ай бұрын

I just happen to have a m68k EVM, 1979 vintage, the very first one in Western Canada...

@lohikarhu734 6 ай бұрын

Ah ha! Since I just happen to have a 6 digit Kelvin Varley divider, I can get a new resistor by matching for my Tektronix dmm, which, somehow, I managed to Woof! the 10 M Input resistor... I do have a 6-1/2 digit HP multimeter, and picked a 10 M from a batch of 1%, that's reading 10.001 M, but now, maybe, I'll try matching a 10 M to the divider chain..

@davidegironi 7 ай бұрын

Great video! I'm building a Conrad Hoffman null detector too. I'm would like to use an analog +-100mV millivolt meter so I'm wondering if I've to put a buffer too, and if so does a simple voltage follower works or do I have to drive another way? Thanks

@klf6992 7 ай бұрын

Reset reset reset...

@myradiovideos 8 ай бұрын

I would think no heat sink compound would cause a failure due to high heat!!

@MatzeMaulwurf 9 ай бұрын

I found two of them in the electronics-dumpster of my company today. Work flawlessly. New cables from the aftermarket and one of them will go on my RV. Tossing out the scrappy 3$ AliExpreas thing.

@mgrabbanisam 10 ай бұрын

hey there,, it's too nice, can i get your mail adress?

@vanhetgoor 10 ай бұрын

Once in history the 68k was advanced, I am getting old.

@specialservicesequipment393 10 ай бұрын

Depending on the manufacturer, you can supply up to 21 vdc , but the internal battery they used was usually no. 6 telephone dry cell

@1962ralf 10 ай бұрын

Very nice, I am impressed, I learned to program Fortran on such a Machine about 45 years ago, but I never learned how the components come together.

@AmauryJacquot 10 ай бұрын

circles on the active low pins are US style symbols. the triangles are the DIN norm that is in use in europe.

@MartianTech 10 ай бұрын

I don't know about US vs European style, but the circles predate the triangles. The 1981 Supplement to the TTL Data Book from Texas Instruments has an entire chapter on "Explanation of New Logic Symbols" and displays new style logic symbols for the new ICs that are presented elsewhere in the book.

@stevenspmd 11 ай бұрын

Best of luck. In terms of subscribers, its a very under rated channel.

@rosco_m68k 11 ай бұрын

Awesome, great video! We'll definitely take your feedback on board for the future! Hope you have fun with the kit! 😊

@androman4085 11 ай бұрын

Sorry, but if you are talking about a multimeter, you need to show it larger, but not your head.

@MartianTech 11 ай бұрын

Oh. Would showing it larger make it any less crappy?

@Rivenworld Жыл бұрын

It will run on USB power (powerbank or mains adapter), it doesn't need batteries if it is running on BUS power. If that is dying after selecting BUS power then it is faulty, I have had this model, the DR70D and currently use the DR701 which all operate on the same principle. As a side note, I also have the DR40 which operates on the same principle and I have never had any problems with any of them so either your unit has a fault or there is something that you are doing that isn't right. These are all perfectly good, solid and reliable recorders. What you are doing here is unnecessarily overcomplicated, sorry if that offends but I speak from over 7 years experience with all of the recorders I have owned and never experienced any issues.

@MartianTech Жыл бұрын

Perhaps you missed the part of the video where I demonstrated the problem. But feel free to post a video demonstrating that this problem is unique to my unit. Perhaps you missed the POINT of the video, which is about solving a problem at little to no cost, using available resources. The lessons apply whether the problem is real, imagined, or caused by a defect. Let's assume I have a defective unit. It is out of warranty, so I can't just send it back to Tascam to have it repaired (which would also mean that I am without the use of the device for some period of time). So what would be a less complicated (zero to no-cost) solution?

@TimTam770 Жыл бұрын

What was the original price?

@MartianTech Жыл бұрын

I think it was around $200, but it's been 30 years since I bought it so I can't give you an exact number.

@3beltwesty 5 ай бұрын

@@MartianTech The list price was 499 in 1982. I bought mine from ITC electronics in Chatsworth (Desoto and Nordhoff) in late 1982 for like 350 ish in a promo sale event. That price was 2/3 a months rent of my apartment. With Inflation that 350 bucks is like 1050 dollars in todays 2024 dollars. That meter was totally well worth it in the testing I was doing. The ultra high impedance available (in an alternate mode) in the 200Mv and 2 Volt ranges is one reason I got mine. These are fantastic meters. Lost the origanal one in Katrina in 2005. Used ones I have bought off of ebay have mostly been good.

@barrybogart5436 Жыл бұрын

Glad you reviewed this. Not long ago (2023), I bought its cousin: a "Tekpower TP8250 Analog Multimeter with NULL Middle Position 0", specifically for the center-zero scales, +- 5 and +-25VDC which are very useful balancing circuit elements. BTW you should always use the mirror scale on analogues to eliminate parallax and maximize accuracy. I have a Triplette VTVM with one of those BIG scales (like the RCA VolOhmyst) and it gets pretty precise.

@barrybogart5436 Жыл бұрын

Thanks for this. I just picked up a 8040A which is an earlier, maybe more portable one. But I will just use it on the bench. One of the battery terminals is broken anyway. I have several 20k+ count DMMs, so this will be a second source of information. I haven't t checked the calibration yet. It will accompany my HP 1740A scope.

@charlesoverton Жыл бұрын

I have 8024 b.

@retro_newbie Жыл бұрын

Just recently found your videos on the pdp 11 and I love them. I'm planning on building a pdp 11 from parts so this series will be really helpful!

@douro20 Жыл бұрын

RZ55 is a Micropolis drive, specifically a 1578. Looks like you'll have to try and find another RSTS/E image, or perhaps RT11.

@MartianTech Жыл бұрын

I'm leaning toward RSX at this point...

@along4190 Жыл бұрын

USB-Serial converter only working in one direction... Some of them do not generate proper RS232 voltages like old gear expects. Supplying negative 3V may not be enough. Try a different brand

@douro20 Жыл бұрын

Will a KW11-K work in there?

@MartianTech Жыл бұрын

I don't think there is a Qbus version of any KW11 card. The only ones I'm aware of are for Unibus. There's a KWV11-A and KWV11-C for Qbus, but I don't know about a KWV11-K

@douro20 Жыл бұрын

There are still modern desktop mainboards with native RS232 ports; my MSI B350 Tomahawk has one.

@CraigPetersen12f36b Жыл бұрын

I have a Fluke 8060A that I still use to this day. So far I have been lucky, no display issues or capacitor leakage issues. I bought it used in the early 90's, it had calibration stickers on it so it may have had the caps replaced at that point.

@simonbaxter8001 Жыл бұрын

Nice project. Where did you get the case from?

@MartianTech Жыл бұрын

The case came from a place called Circuit Specialists: www.circuitspecialists.com/collections/metal-instrument-cases

@simonbaxter8001 Жыл бұрын

@@MartianTech Thanks for the link.

@douro20 Жыл бұрын

Wasn't the 11/34 the first one with the interactive console?

@MartianTech Жыл бұрын

I think it was the 11/04, but I could be wrong...

@douro20 Жыл бұрын

@@MartianTech You're right, it was the 11/04. It was also the first PDP-11 to have a single-board CPU.

@lesstime1678 Жыл бұрын

i have 1 like that from 1983 , never use it,,,,,,,, is in the box all that time , was a gift , just because i have more than 100 meters i never open the box , i use B&K , RCA SIMPSON VTVM stuff

@uni-byte Жыл бұрын

It's easy to remove that fuse holder wire and usually better and safer if you do.

@gerardzi7930 Жыл бұрын

I have the same HP

@emuhill Жыл бұрын

So basically it was that 6822 chip after all. What did you do swap it for another chip? I do believe that evil company at the time this version of basic came out was in Albuquerque.

@garyramsey4275 Жыл бұрын

I worked at HP in the 1980s, and I repaired many of this specific model number. The reason HP designed this hybrid was for 2 specific reasons: First, because the voltage divider resistors could be more easily laser trimmed for precision. Secondly, and more importantly, the switching FETs were added onto the same substrate as the resistors for temperature stability. The theory was that any thermal drift would be minimized due to the added mass of the substrate, and in any case, all components on the substrate would drift equally in the same direction, thus effectively canceling the net effect of temperature changes. The idea worked reasonably well, and it is still used today in modern instruments. Your idea of building a replacement board for that hybrid is excellent, but of course the thermal benefits of that hybrid will be lost. In practical terms, I would think it would work fine, considering the level of precision expected from this instrument.

@ivolol Жыл бұрын

Nice replacement! I dunno if there'll be a final part, if you could include an overview of how that part interacts with the meter to create readings, that would be super awesome.

@inse001 Жыл бұрын

What calibrator do you use?

@MartianTech Жыл бұрын

Everything is identified in the video: DC Volts at 2:35 - Fluke 343A, AC Volts at 7:23 - Fluke 5200A. Current source is homebrew, but I now have a Valhalla 2500.

@button-puncher Жыл бұрын

You can't get them anywhere...oh wait there's three of them here...LOL! eBay find? Thanks for the refresher on the chip differences. It's bee a good 20 years since I've worked with logic chips.

@button-puncher Жыл бұрын

Thanks for showing it off. I just picked up an 1102 and wanted to see what other faults people are seeing. You sound like "The Dude" from Big Lebowski. ;)

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