TMG-303 Test Message Generator Repair

Рет қаралды 33,479

6 ай бұрын

We got a beautiful and complicated CDC TMG-303 Teletype Tester from a viewer. Which does not work and does not have any documentation. But that's not going to stop us, right?
Usagi Electric Channel: / @usagielectric
Stuff that supports the channel:
- Amazon links for the tools I use in the lab (supports the channel if you buy from there)
www.curiousmarc.com/amazon-links
- Channel merch on Teespring: teespring.com/stores/curiousm...
- Support us on Patreon: / curiousmarc
"Elevator Music" Credit: Crinoline Dreams by Kevin MacLeod
Our lovely sponsors
- PCBWay: fast turn PCBs, www.pcbway.com
- Electro-Rent: www.electrorent.com
- Keysight: test instruments: www.keysight.com
- Samtec: connectors: www.samtec.com
- R&D Microwaves: rdmicrowaves.com
Get more technical info on the companion site: www.curiousmarc.com
Contact info: kzfaq.infoa...

Пікірлер: 140

@ke9tv 6 ай бұрын

The Army definition of portable: there's a handle on it.

@christianweagle6253 6 ай бұрын

And they used to say "two man lift". Now they say "team lift".

@orbitingeyes2540 6 ай бұрын

Does it take 1 platoon or less to move it? If yes, it's portable.

@AndyGoth111 6 ай бұрын

Haha wow, I was just thinking about you a few minutes ago, happy to see you here

@acmefixer1 6 ай бұрын

I worked on the Army's AN/TPS-1G, which is a Radar. The T stands for transportable; the cases have four handles and weigh up to 330 pounds!! 😭

@brunoramey50 6 ай бұрын

How the hell Master Ken can work in the background with so noisy colleagues ?! He has my full support

@ScottGrammer 6 ай бұрын

The old Heath cap checker tested the caps at a higher voltage, and that's what it took to make the caps act up. The HP checker only used 6V., not enough to really test the cap.

@MichaelOfRohan 6 ай бұрын

Since you know better, which equation would throw C off so far with such an excessive V? Youre pooping in a small cup. Is that the proper analogy? Cheers.

@ScottGrammer 6 ай бұрын

The issue is leakage, not capacitance. Leakage current is dependent upon the voltage placed across the capacitor, when the capacitor is failing. Many failing capacitors will test fine at a low voltage, but when tested near their rated voltage, they will leak like a sieve. And yes I know that the Heathkit tester was set to put 25 volts across a 15 volt capacitor, which is not really a great idea but it did prove that the capacitor was bad. Frankly I would have just changed them anyway considering that one had already blown a hole in its own seal, and of course the fact that replacing them fixed the problem proves that they were the problem.

@colinstu 6 ай бұрын

Have you ever looked into Mr Carlson's cap tester? It's low voltage too yet somehow is supposed to be way better than most cap checkers?

@ScottGrammer 6 ай бұрын

@@colinstu Yes, apparently it is. I don't know how it works, but perhaps I should ask him. I think he actually makes the schematic available for channel members, but I'm not sure.

@colinstu 6 ай бұрын

@@ScottGrammer yes, for his members and patreon I think. Haven't gotten around to digging into it but it seems pretty convincing.

@jeremiefaucher-goulet3365 6 ай бұрын

20:55 Today I learned why serial protocols are designed with stop bits. Mind blown. Thank you.

@tomteiter7192 6 ай бұрын

hehe, same here! While the fundamental function of the stop bit in the protocol is quite clear, I never understood why there are different lengths!

@jeremiefaucher-goulet3365 6 ай бұрын

@@tomteiter7192 The fundamentals? From a software and electronic perspective, it always looked superfluous to me. In fact I never understood why the common default didn't become 0 stop bits.

@tomteiter7192 6 ай бұрын

@@jeremiefaucher-goulet3365 Hm. You're right, since the receiver is essentially "counting out" the incoming bits after the start condition, there's really no need for a stop bit... ah well, it SEEMED clear to me when I first thought about it a looong time ago :D

@tomteiter7192 6 ай бұрын

@@jeremiefaucher-goulet3365 Oh, and just a few days ago I learned that some hardware really does not use the stop bit. I tried to reverse engineer some protocol, and was sure there were 4 bytes at 8N1. Testing with a PC an an FTDI USB converter it read 4 bytes every time. Transporting my findings to a Pi Pico using Micropython, I read all kinds of funky bits, sometimes three, sometimes 4... In the FTDI dumped data the last byte always had bits 0 to 5 set to 1, which seemed strange. turned out I simply had the wrong baud rate (I just tried default rates, and at 115k2 data seemed to come in nicely) A round of scoping revealed that the baud rate was exactly 100k! So the FTDI tried to make the best of the incoming data, and simply filled the last bits, stubbornly reading the then resting serial line.

@jeremiefaucher-goulet3365 6 ай бұрын

@@tomteiter7192 Sorry for turning your world upside down 😉

@humidbeing 6 ай бұрын

Wow Marc, Usagi, TubeTime, and (I think) Master Ken all in the same room? Awesome.

@CuriousMarc 6 ай бұрын

Yes, Master Ken has been in the background of many videos of late, furiously working on his mechanical Air Data Computer that refused to behave. But he’s beaten it into submission now.

@tomteiter7192 6 ай бұрын

@@CuriousMarcoooo! Can't wait for THAT video :D

@minty_Joe 6 ай бұрын

All that's missing are cameos by Jeri Ellsworth, Fran (Franlabs), Adam Savage and Cliff Stoll. I can sense the super genius brain power radiation emitting out. Very strong levels, I'm afraid.

@Derpy1969 6 ай бұрын

Seeing Usagi Electric on Marc’s channel is like seeing a crossover episode on TV in the 70s of your two favorite shows!

@TheJimbodean67 6 ай бұрын

I like the window of time for these type of devices where IC’s are starting to come into their own yet are still constrained by the analog interface. The infrastructure and industry supporting manufacture/maintenance of this kind of equipment was so dialed in by now, and really allowed those electrical and mechanical engineers to shine. The space/aviation field is about the only place you still get to see this standard of construction. One small yet important window into the advancement of technology and how we used it.

@MattMcIrvin 6 ай бұрын

It reminds me of the earliest arcade video games, where you've got some IC-based circuitry but there's also all this one-off custom hardware to do things like generate specific noises, and graphical elements represented by tape on the screen, things you wouldn't think of in the later era when it was easier to just do it all by reprogramming general-purpose commodity hardware.

@ifitsrusteditsmine 6 ай бұрын

The excitement emanating from this guy is so relatable. 99.999999 percent of human kind will never understand how old tech can be exciting

@senilyDeluxe 6 ай бұрын

There's an exception to this rule: Vintage cars. Pretty much everyone thinks these are cool. They definitely are! But old computers? Old video games? Watching movies on VHS on a CRT TV? This guy's got something wrong with his brain!

@douro20 6 ай бұрын

I have an Airpax hermetic 3-pole breaker somewhere, which was rated for 100-250V at just 3 amps. It came from an old US Navy SATCOM teletype interface- a small rackmount box containing shielded boards containing TTL logic chips and no microprocessor. It was designed to take SATCOM messages as input and perform translation so that the old Baudot teletypes which were still in common use could be connected to modern SATCOM equipment.

@simontay4851 6 ай бұрын

4:48 wow, amazingly beautiful wiring! Someone really took their time to do it properly.

@rocketman221projects 6 ай бұрын

I was expecting it to have the message on a rotating drum or something. I was surprised to see a ROM in there.

@cncshrops 6 ай бұрын

70s inside, 50s outside. Feels like a device with a pedigree.

@Herby-1620 6 ай бұрын

The bit rate of 134.5 is used for an IBM 2741. It takes a 6 bit character, with a parity and a single stop bit. This is a total of 9 bits. This amounted to about 15 CPS, which is the limit of the Selectric Mechanism. Note this is a 6 bit code, and has upper/lower case characters. The shift required a character to function (much like LTRS/FIGS) on an older Teletype (model 15 for example). The 6 bit code came in two different types: "Correspondence", or "BCD". If you look at a normal Selectric typewriter it has all the characters out of order, that is correspondence code. If the had some order, it was BCD code. Stanford used these in the late 60's thru the 70's as hard copy terminals.

@beefchicken 6 ай бұрын

Hey I have a TMG303, and its partner the SDA103, a serial communications analyzer. I had to modify the SDA103 to support 45.45 baud, by modifying the diode matrix used in the baud rate generator. There’s a video of it somewhere on my channel.

@CuriousMarc 6 ай бұрын

Awesome! You do have a video on its sister box, right here: kzfaq.info/get/bejne/qbh5jbyVs6_Kj4U.html . And on top of this you reverse engineered what the big diode matrix does (it digitally encodes the divider to produce the correct baud rate). Impressive job!

@AmazedStoner 6 ай бұрын

Makes me wonder why we don’t have modern capacitor testing equipment with a proper leakage check

@CuriousMarc 6 ай бұрын

Because we’d soon discover that all modern caps suck. Mwahahahaha.

@pelor92 6 ай бұрын

Plenty of modern instruments can be used to do that measurement (some LCR analyzers with optional fixtures, insulation testers, etc.), the feature is however not common in general purpose instruments because it is a fairly niche test to carry out as not many people work with HV electronics anymore (let’s say >24V) compared to when we had to deal with tubes

@Sixta16 6 ай бұрын

Just plug it to a voltage source of your preference and measure the current, no extra special instrumentation required. :-/

@gnudarve 6 ай бұрын

I set 8N1 into terminals for so many many years, not really knowing why the number of stop bits was needed, a parameter that never ever seemed to change. Until today that is. It's to allow time for hardware to keep up with the data flow without demanding a lower rate, that had never occurred to me because I came in just a little too late to use mechanical teletypes. Marc you have handed me a puzzle piece that fits squarely in a little void in my mind, I feel one unit more complete for it. Thank you tech bro, thank you!

@lwilton 6 ай бұрын

Useless character set trivia: IBM wasn't the only computer company to use EBCDIC. The Burroughs corporation used it on all of their computers from the late 1960s onward. Originally IBM had BCD -- Binary Coded Decimal. Burroughs had BCL -- Burroughs Common Language. BCL was BCD with a few of the character glyphs changed to things more appropriate for the ALGOL language. These were 6-bit character codes. In the early 1960s Burroughs adopted EBCDIC for all of the new mainframe computers. This was an 8-bit character code. Again there were one or two glyph differences between IBM and Burroughs, but the sets were otherwise compatible. Originally EBCDIC was only uppercase, but was soon extended with lowercase. In EBCDIC the lowercase collates before uppercase, the opposite of ASCII. In 1963 the ASCII-63 standard came out, which defined an uppercase-only version of ASCII. It wasn't until 1967 that ASCII-67 was approved. This is the ASCII we all know today. EBCDIC with lowercase was around most of a decade before ASCII with lowercase was. EBCDIC was a common interchange character set between many mainframe models from many makers.

@MCPicoli 6 ай бұрын

Siemens... Made in Brazil caps, brings me a decades old memory... I encountered exactly this type and value of capacitor when repairing an old b&w (Brazilian) TV set in the 1980s... Blown in the same way too!

@jamesbrewer3020 6 ай бұрын

love the smell of teletype oil in the morning..

@ivancosta 6 ай бұрын

I have not made to the end of the video but at 7:36 the capacitor markings is saying it was made in Brazil ! As a brazilian, what a surprise!

@Sergio-he8sw 6 ай бұрын

Probably made in Brazil by Icotron plant in the 70s.

@GusFernCa 6 ай бұрын

I remember many years ago, I saw a "Quick Brown Fox" ROM being sold at a local Radio Shack store. I wondered at the time who would ever want that, and here's the application. But why on earth would they carry that in hundreds of retail stores throughout the country?

@michaelturner4457 6 ай бұрын

They were probably manufacturer surplus. Radio Shack sometimes did package and stock surplus components in their stores.

@jaoswald 6 ай бұрын

One possibility: for a Morse code test project? The surplus hypothesis is a good one also.

@christhirion9474 6 ай бұрын

I spend many a hour lacing our old Honeywell DCS input cards, good old wire wrapped and artworks in their own right

@TheFleetz 6 ай бұрын

Yet another brilliant and super interesting historical engineering product update. Fascinating! 👍 Wishing you and all the CuriousMarc team the compliments of the season and a Very Merry Christmas.

@fumthings 6 ай бұрын

i seem to remember that the rubout feature used to work in a neat way when making a punch tape, the tape would pull back and the rubout character would repunch the tape with the unprinted character and this worked because it was all holes punched. when you put the tape in the reader to send it, the received printout was flawless. (before this you would have backspaced and then xxx over your mistake.) can anyone confirm this?

@CuriousMarc 6 ай бұрын

Correct, the Baudot Letter characters (all 1’s) could be used to overprint a mistake in a punch tape, punching all the unpunched holes and making the character a No-Op effectively. That was ported into the 8-bit all ones character in ASCII and was used for the same purposes on tape, hence the “rubout”. It was literally the whiteout of paper tapes. Eventually became the backspace on CRT terminals.

@pietpaaltjes7419 6 ай бұрын

Nice, thanks for the history lesson! 🙂

@paulstubbs7678 6 ай бұрын

I used to work in a repair shop fixing Siemens & Sagem teleprinters, and some of the test equipment. I even acquired some gear, sadly now all gone, If only I knew...... All I have now is a 50Bd time and date generator from a telex exchange & a Sagem paper tape reader. I worked there for quite a few years, and this all brings back some good memories, trouble was I was getting into computers back then, and my main drive was connecting this gear to my brand new Tandy/Radio Shack TRS-80 computer and Amateur/Ham radio, so acquiring mechanical machines (very easy back then) was not on my agenda.

@RodCornholio 6 ай бұрын

Now if it typed, "All work and no play makes Jack a dull boy."

@MarcelHuguenin 6 ай бұрын

Magnificent device and what a blast of a party you had there ;)

@CTSFanSam 6 ай бұрын

I am glad I spent a few years behind an ASR-33 in my early days. This video was just plain fun to watch.

@grubboy3514 6 ай бұрын

Great to see Master Ken in the house...

@jagerfreak2702 6 ай бұрын

Yes yes yes, best friday evening programm

@euroclassicsnation 6 ай бұрын

So much fun to watch. I don’t understand a lot of it but it’s so interesting

@spewp 6 ай бұрын

Is this the first time a piece of vintage equipment has just worked on this channel? Inconceivable!

@markgreco1962 6 ай бұрын

Thank you for always showing us viewers interesting content.

@malcellery1538 6 ай бұрын

Nice to see a bit of 5 unit and foxer. Wonderful bit of kit.

@tekvax01 6 ай бұрын

Soooooooooooo cool Marc! I'm totally gelly... I'd love to have one of those "portable" teletype machines!! Excellent content as always sir!

@paulcohen1555 6 ай бұрын

"Modern" test equipment! Original 74xx TTL IC's. Axial Siemens capcitors! WOW!

@tim0steele 6 ай бұрын

This is why many teleprinters including the Creed 7E have a huge spring to return the carriage as fast as possible while damping the last bit of motion with a dashpot to prevent damage, in an attempt to return the carriage in one character time. Also, if you dump the ROM then you could replace it if it ever goes bad.

@North49Radio 6 ай бұрын

It is hard to imagine how much more I would enjoy your videos if I knew what was going on, but I do love them. Thanks, Marc!

@TradieTrev 6 ай бұрын

That's pretty damn cool! We have to remember in computer science theses are the true grand daddies!

@confirmhandle 6 ай бұрын

Mind blown. Thank you.

@metallurgico 6 ай бұрын

i love old electronics! it's so fascinating

@michaelmiller641 6 ай бұрын

Absolutely fascinating!

@wdavem 6 ай бұрын

That's a really nice little box!

@jxh02 6 ай бұрын

I suspect that DE near the end of the line is for you to insert your call sign after it. But only enough switches for two characters, repeated 7 times? Hmmm...

@CuriousMarc 6 ай бұрын

Yes I was wondering about that too. Maybe you could order it with a special ROM with your call sign on it, or program it on the diode ROM arrays?

@NivagSwerdna 6 ай бұрын

That is such a lovely thing

@twol78s90 6 ай бұрын

I would wager that the two diode ROMs in the device are used for A) baud rate generation by providing preset values for counter chains to generate the baud clock, and B) address offset in the ROM for the beginning of the variously coded versions of the QUICK BROWN FOX text.

@huntabadday2663 6 ай бұрын

Wow! That is a beautiful machine. I decided to search and wow, literally no documentation at all. I found one document that briefly mentions it. Thats about it

@darrenerickson1288 6 ай бұрын

Awesome video. Now hook it up into the Apollo Comma test setup! 😂

@bertspeggly4428 6 ай бұрын

Love this old stuff as long as you don't actually have to use it!🙂

@radio-ged4626 6 ай бұрын

Wow, haven't seen CDC kit since the 1980's I used to refurbish CDC Cartridge Module and Storage module drives for the British Police and for Rank Hovis. It would be great to see you work on one of those if any still exist.

@tony359 6 ай бұрын

amazing!

@BaptisteCanton1 6 ай бұрын

what a beauty !

@medicman4444 6 ай бұрын

Yey a new Marc vid :3

@alexlavoie9696 6 ай бұрын

You guys are the coolest nerdz! Keep up the good work!

@gerryjamesedwards1227 6 ай бұрын

Marc, if you want to get rid of the sticker residue without mucking up the silkscreen lettering, Goo-Gone works really well. I have an old low-V AC power supply that had stickers everywhere but Isopropyl reactivated the ink for the lettering, despite it being 50 years old. The GG left it intact but got rid of all the sticky stuff.. Just a thought.

@MovieYellow19 6 ай бұрын

Just subscribed to the channel, i don't know what those things are, but i just know that i love to see buttons and something mechanic and old, i'm 19 and that type of stuff is so wonderful! it relaxes me :D thanks for showing them all! even if i don't know what are those things xD

@oloquino 6 ай бұрын

These machines are very interesting! I wonder how intelligent the engineer who designed them was.

@EdwinSteiner 6 ай бұрын

That thing just has the most adorable form factor. What a cute device! Great that you got it working! I hope it will also get a well-deserved exterior cleaning!

@andrewbernhardt3061 6 ай бұрын

I remember a device like this (if not the same) in my Air Force teletype maintenace course in the early '80's.

@DouglasFish 6 ай бұрын

USAGI! I have no idea where you guys are, but it would be fun to do this kind of work with you

@MatthiasWelwarsky 6 ай бұрын

When you see the thumbnail and instinctively know the music the video will open with 😀

@lmiddleman 6 ай бұрын

19:09 Ken's like, where are my ear plugs?

@ImmanuelFTL 6 ай бұрын

Hey guys. I watched the entire AGT restoration series over just 24 hours. Thoroughly enjoyed it

@nikreichel2232 6 ай бұрын

The gold caps reminded me of the Frako (Frankfurter Kondensatorenwerke) - Caps that were mostly shorted in the Revox-Reel2Reel Recorders I serviced. These however are branded by the S-H-Sign Siemens Halske (or maybe rebranded?). Interesting...

@filmclipuk 6 ай бұрын

Nice tee-shirt, @usagielectric at 11:05, but is that a teeny-tiny-toy Marshall speaker in the b/g there? 🤔

@user-ij4lt4ry6t 6 ай бұрын

Спасибо за интересный выпуск

@benjaminhanke79 6 ай бұрын

03:59 "click clack" This is the most epic useless machine on KZfaq. 06:10 I always thought that "Fox message" was a Windows 95 thing. 05:14 It's a "FULL BRIDGE RECTIFIER!"

@MattMcIrvin 6 ай бұрын

I remember "quick brown fox" being used in typing instruction-- and just being cited in trivia books as a short phrase with all the letters of the alphabet, though there are shorter ones.

@bigsarge2085 6 ай бұрын

👍👍

@enzofitzhume7320 6 ай бұрын

👍👍👍👍👍👍

@whiskeytuesday 6 ай бұрын

How neat. What is it about test equipment?

@jlwilliams 6 ай бұрын

03:19 “Marcia, remember to wear your red nylons tomorrow… we've got a photo shoot for the 360 system…”

@thesteelrodent1796 6 ай бұрын

gotta match the machine ;)

@benjaminhanke79 6 ай бұрын

After hearing fancy pants guys story about the HP catalogue picture I believe that's exactly how it happened.

@tomteiter7192 6 ай бұрын

wow, I suddenly understood what the different stop bit lengths are about and why most modern systems seem to be totally unaffected by this setting. I often use a serial monitoring tool, that doesn't even have the setting for it...

@gusbert 6 ай бұрын

Hello CM! When are you going to show the HP 1600A?

@CuriousMarc 6 ай бұрын

Actually I partially fixed it last week and connected it to the 1607A for the first time. Still not behaving a 100% correctly, but the display is great now.

@gusbert 6 ай бұрын

@@CuriousMarc Great news, hurray for HP!

@68hoffman 6 ай бұрын

kool

@user-lk6pg7wo1b 6 ай бұрын

These diodes are not ROM, they are encoders/decoders

@Stelios.Posantzis 6 ай бұрын

2:14 Why do the switches have plastic-dip coating over them?

@MrRtkwe 6 ай бұрын

Can you rewire it to use the superior version "Sphinx of Black Quartz, Judge My Vow"?

@pietpaaltjes7419 6 ай бұрын

4:00 nice implementation of the useless machine 😅

@shanelellno7457 6 ай бұрын

이거 복원 수리해서 뭐에쓰나요? 윈도우11에 사용가능? 안되면 쓰레기

@MD4564 6 ай бұрын

I reckon you could do a ROM dump with the correct ROM dumping, make a new rom.

@RetroJack 6 ай бұрын

Rubout length? About 5 minutes, on average. 😋

@notsogreat123 6 ай бұрын

Electric Bunny ;-)

@aaronr.9644 6 ай бұрын

so this must have been one of the easiest repairs in this channel haha :D

@scowell 6 ай бұрын

Any old box you check the fuse! Chances are you'll find a 20A glass automotive fuse... bad.

@medicman4444 6 ай бұрын

Anyone else having issues viewing the Vis or setting quality higher than 360p?

@ScottGrammer 6 ай бұрын

When videos are first published, they go up in 360p first, with higher resolution versions going up a little later. You may have viewed the video right after it first posted.

@gusbert 6 ай бұрын

On first upload YT takes some time to add the higher quality streams.

@TradieTrev 6 ай бұрын

@@ScottGrammer It did to me; I'm on a StarLink CDN so it changed into 1080 when I was watching.

@ScottGrammer 6 ай бұрын

@@TradieTrev Ahh. Could be a bandwidth problem.

@medicman4444 6 ай бұрын

@@ScottGrammer hehehe mark vids is being super popular XD

@SOMERANDOMDUDESomething 6 ай бұрын

Haich peas devices featured. Yeag

@CashMattock 6 ай бұрын

Would you consider selling this??

@TrimeshSZ 6 ай бұрын

I'm surprised about the caps - I have a bunch of WW2 German radio gear with those Siemens Halske caps in them, and they are all still OK 70+ years later.

@AcornElectron 6 ай бұрын

I had no interest in these machines until I did.

@TimoNoko 6 ай бұрын

Anybody embarrassed of these horrible clunky devices? I almost bought slightly used ASR-33 for my 8080-SBC. The price was something astronomical , probably 3 months wages at Nokia Gummiboot factory in 1976.

@erikdenhouter 6 ай бұрын

6 commercials in 10 minutes, with most infantile sounds to 'attract attention', I had to stop there. Sorry.

@CuriousMarc 6 ай бұрын

Thanks for letting me know! That's insane! KZfaq added commercials breaks behind my back! I removed them all but the standard one in the middle. Let me know if they reappear. As for infantile sounds, I'm not sure what you mean. KZfaq added some sounds to the video?

@erikdenhouter 6 ай бұрын

@@CuriousMarc At the start of video's I get mostly annoying children's games commercials with a lot of loud screaming and slamming (from "Hero wars"). It sometimes scares me even to start a video. Never searched or played a game on YT in my life, so it looks like a leaky algorithm too 😂

@CuriousMarc 6 ай бұрын

@@erikdenhouter Ah thanks. Unfortunately I don't have control of what type of pre and post roll ads they put. Sorry about that. But at least the video should be watchable now without constant interruption. I'm glad you alerted me to it.