Upside down SMD using a routed hole......Ooooh, I so wanna do that on my next Pcb.... :-)

This video is the perfect representation as to why "right to repair" should be a universal thing. Amazing stuff!

Traces running off the side are not for test, they are to connect all the copper together for gold electroplating

24:56 That bottom contact on your ribbon cable appears to be flapping about in the breeze. You can usually tack them back down with a tiny spot of superglue applied with a needle on the back of the lifted track.

The Y2K bug started hitting people in 1975. That was in the long term loan/investment industry, especially mortgages.

lol... I opened and ran the original Tandy Repair Center in Pensacola FL.

I just love Tandy's process. I had a 4-pin color plotter of theirs and wanted to interface it to my Apple II, walked up to my local store and ordered the service manual, took a couple of days, had EVERYTHING you need. Nothing finer than Tandy IMHO. End of an era.

Very good deducing! Finally a good video to start my service day with. Simple enough, but only though understanding the circuit first. If that would not of had schematics, it may not have been possible. Good job. Think what we could fix today, if service manuals would not have ended in the early 1990s. Back in the day, the company I worked for built a modular ultrasonic system. There was an over all service manual, but then every module had it's own service manual. Even the I/O module which was basically only a back-plain board, a ribbon cable and I/O connectors had a 40 page service manual! The service manual for the Receiver was probably 200 pages, the CRT display module was at least that many pages. It was more of a pleasure being a electronics technician back then. Now service manuals are gone and a lot of circuits have been replaced with magic FPGAs. By about 2006, in the service department, I was the liaison to engineering for new NPIs. I was the one writing service manuals and I tried to bring the glory of the 1970's and 1980s back to them. I would be able to get theory of operation from engineering documents and working directly with the engineers, attend NPI meetings, etc. I brought back the several hundred page service manual. Parts details and part numbers were a huge part of it too. Even the theory of what the FPGA was doing and its responsibilities were a huge help in trouble-shooting failed boards. I worked to included simplified schematics again. Even in some areas exerts from component data sheets. Microsoft word had matured by the mid-2000s and was able to handle huge 300+ page documents loaded with graphics, different page sizes for different sections, etc., which was great to keep it all in one document. I was quite proud of what I had been able to do. I kept that up until about 6 years ago, until we were shut down and production and engineering move off-shore. All the higher ups really wanted was board swaps. Why fix a board for $500 when they could sell replacement boards for $2500. This did alienate customers, and alienated the technicians who didn't want to be board swappers. ...And then they would never stock the replacement boards. Electronics has become quite a throw-away mess. There for about 10 years, or so, I was able to bring back the love of servicing our boards with extreme details available to do the job.

Repairing stuff looks so easy when you do it, Dave!

I wasn't even a thought in my parent's brains when this beauty came out

Chicker Dinner ? O_o ... A "bobby dazzler" Dave, nice fix. Excellent diagnosis deduction there. Saved another one! Cheers,

Fantastic! Enjoyed every second of it! Thx!

excellent video , fun to watch the process of finding the issue and how the scope comes in handy

You're lucky that backup battery isn't gone. I would replace it before it spews everywhere. I think most people use a 2032 with a diode to keep it from getting charged.

Really love the vids where you analyse a problem, get the scope out, poke around a bit, then find a solution. So much diagnosing and testing approach can be learned. Winner winner. Thanks so much.

I don't have Dave's knowledge or none of the probes, but first thing I always do is put PCB under microscope and look for physical damage...but doesn't do for a good build-up video... Dave is truly special the way he presents, educate and entertain.

24:57 did no1 see the bottom pin?

Awesome troubleshooting video. Double thumbs up for the way it was presented!

Great presentation and pace! Like it very much.

More fixing vids please..... we can all learn (and be entertained) so much when your knowledge is applied to something that is broken

That was a fantastic repair video. Nice work.

Wonderful TS’ing Dave, and thanks for sharing!

That was my laptop in University. I used it to take notes in class.... Damn I'm old.

When Dave makes videos on his own expertise, he makes great ones. I loved this!

The 1980's version of a Macbook with liquid damage...

The original Model 100 was such a fun PC to use. The bus and port access allowed easy connection to external circuits, and BASIC had access to all the pins, making it a key tool on my bench. My favorite use was validating the datasheets for new parts, particularly sensors and stepper drivers. Never had a Model 102, as the MS-DOS takeover of the universe was pretty much complete by then.

Always nice to see a bit of kit brought back to service! 👍

This video is underrated. Very enjoyable repair!

I loved this one. Very clean transition from hypothesis, inspection of schematics, probing, and finding the bugger responsible. Well done

Great find Dave... WELL DONE!!! 10/10

Good on you mate. repair videos are awesome.

"Chicker Dinner" :) You have to love issues that are simple to fix. That unit now has some new life breathed in to it. Interesting to see that Varta NiCD battery. It is the exact same one I used on a 25-year old CPU board I designed.

Fantastic analytical skills here, really demonstrates your true skills. Well done 👏

Great video. Easy to follow your thoughts and troubleshooting techniques for a newbie hobbyist like myself. I would like to see more like these. Thanks.😁

Had a similar model (NEC ?) back in about 1991-1992 time frame. Connected it via RS232 to a daisy wheel typewriter. Used it to send out "shotgun" resumes to scores and scores of companies - with no results.

Great Video Dave

I used these at work years ago to connect to data loggers at power plants using the serial port and the terminal program built in. they were tough, never crashed and batteries lasted forever. I used one as a wall clock for years, these didn't have a built in failure point. they were made to last.

YES! I have one of these (still working).... great video!

Great teardown- and yes-- schematics!

Great fix. I would love one of these.

Wish I had this problem. The LCD on mine has gone completely "come a gusta"

The winner feeling when you catch the bug. You really get that feeling into your videos :)

@25:30 looks like there is a varta battery on the board (suggest replacement before it leaks and destroys the board like just about every other vintage device)

Great job, Dave !

Well done.

Winner Winner - Chicken Dinner! What a laugh!! :-) This is an amazing repair session! Thank you for sharing it Dave!

Always glad to see videos on these portables. I wanted one for years and then went overboard after I bought the first one. I have one from the RadioShack corporate bankruptcy auction that is not functionin. I have another working model 100, a working model 102, 2 non-working model 200s and a non-working NEC PC-8300 that I have to find time to troubleshoot.

Well done Dave,great job

Please do make that video you mentioned about the modem, I'd love it see it!

I have a Cambridge Z88, very similar form factor. I see you've covered it before :)

Nice bug hunt there Dave, enjoyed your effort and success!

When I first saw the "Chicker Dinner", I thought, some more dots missing on the display. Nah, just a test for the observant. :)

good catch sir :)

Excellent deduction there Dave

Really cool PCB layouts on these things! I actually just fixed up my 102 a couple hours ago. Saved it from the "electronics recycling" pile at the local dump a few months ago. Anyway, only issue was old memory battery - replaced that, and the nagging one, the function keys not working. Ended up tracking it down with a logic probe to a bad trace under the PIO chip. Soldered a bodge between PA7 and pin 8 on the keyboard connector and bob's your uncle! Fully functional unit! now just to wire it up to my theoldnet wifi modem emulator for a sweet mobile terminal! Also, what a joy it is to program in BASIC on that keyboard... mmmmm... That empty expansion rom socket is looking mighty lonely too.... maybe some 8085 assembly time :)

Here is the Blinky program of those days; 10 PRINT "HELLO" 20 GOTO 10

Beautifull craftmanship ... imagine the news we were reading back from the LA Olympics in 1984 written on a Tandy.

Great video. Great fault finding. Winner Winner Chicken Dinner 🍽

Nice Analysis !

I cheered when you found the fault. I really enjoyed watching you track this bad boy down.

Real nice repair

cool stuff Dave.. id love to see ya do more retro computer repairs like this.... and maybe that Sinclair C5 sometime! :P

24:56 the lowest contact pad on the ribbon looks concerning!

Been ages since I last seen one of these in person.

The Model 100 is the one computer I used to death in the 80's. I wrote every paper in college on it (printed though the parallel interface on my Olivetti typewriter) and I spent hours typing on BBS systems through an expensive 1200 baud modem I bought. Naturally I also used it for nefarious purposes. I wrote a simple Daemon Dialer to call every number in my city looking for computers to hack into. And since you could only dial into the high school computer from within the school's phone system, we brought them to school and plugged them into random phone outlets. Our greatest achievement was taking one into the phone room at school and using alligator clips to connect the modem into the line that the front office terminal used. We then got someone in the office to log in and our Model 100 captured their password.

Oh man. I still kick myself for selling mine back in the day. I had one all setup for a great Packet Radio rig. Such awesome little units. Great to see again :)

Good jobby very entertaining thanks Dave

Nice Save Dave!

The serial number starts with 61...probably a sub-version for Australia, The modem would have been approved by Telecom or (maybe the PMG?) for use in Australia.

Gday Dave! Brilliant video on how to board level troubleshoot electronic equipment. You can see the process you go through to resolve an issue. Sometimes you have to just dig out the oscilloscope to properly troubleshoot the issue. Had you just decided "Oh its that chip," you would have wasted time pulling the chip just to find out that was not the fault. Too bad you did not run this during Septandy. This would have been a great video for that event.

"Chasing a red herring down a rabbit hole" - This is like an old style Dave video :)

An old news reporter gave me his Olivetti M10, one of the many clones of the original Kyocera / Tandy 100. He used it for over 20 years to write articles! What a nice little machine!

Chiker dinner ;) LOL ;)) well done mate!

Louis would touch himself after finding that corrosion until the cows come home.

I remember gaming on one of these. Such a great machine. Belonged to my grandfather

I remember pouring over the RadioShack catalogs as a little whipper snapper really wanting one of these! Fast forward to 12/31/1999 as an escalation engineer at Lucent on standby in case all the phone systems started crashing around the world at midnight. Nothing to see, move along now...

So interesting that they cut holes in the board to mount the chips upside down, because even back then, you could order packages from the manufacturer with a "flipped" pinout. (Which is called a 'reverse type').

Crikey, I used to use one of those to monitor the output of A0 drawing tablets over serial comms.

That battery is all crusty. Please replace it ASAP or at the very least remove it before it destroys the board. It's only a matter of time. And as someone already stated a trace is coming off the computer side of the display ribbon cable.

I bought one of these new in '86. Sold it lightly used, in the box, for $480, and the disk drive for it for a whopping $675 two years ago. Love how they reversed the chips and used the board thickness to place them. The only utilitarian program I wrote on this was to estimate how much I would have to have saved by the time I was 40 to retire. I made a mistake in overestimating future rates of return - ha ha. I later retired at age 42, but that included an unexpected inheritance from my mom of over a million. So my program was a little off - garbage in, garbage out. It did have a very nice keyboard for the time.

Enjoyed that. Cut my teeth repairing various 8 bit products back in the day at Unilab. I had BBC micro S/n 00002 on my workbench

That definitely looked like flux ate the track off Dave. good find!

Blimey! A fix video where you fix it! lol

amazing

We had Tandy stores here in the UK. I always came out with something random.

Chicker dinner? Was that a typo Dave?

I love that it's "chicker" :D

I remember Y2K well. I was working for IBM at the time as a software engineer. We spent 6 months prior to 1st Jan 2000 combing our source code for date manipulation areas and fixing them if necessary (very few if I remember correctly). Thank heaven for grep! Then I was volunteered to be on call over new years eve / day. Of course this meant I couldn't drink in case I had to leap in my car and go to fix something. At least they had the decency to pay me double time overtime rates and give me a mobile phone which I got to keep. As it happened we'd got it right and the whole thing was a non-event. The phone never rang once.

to the left of the break in the trace you kept pointing to, there's a gap that looks like it was scratched away intentionally

24:15 I spy Varta, Destroyer of worlds! I'd get that swapped out regardless.

Cool stuff, Tonight is Stack dinner

Nice video, reminds me of mine years back trying to hack using the acoustic coupler on a pay phone. What microscope are you using to do those "hex" zooms I need one. Thanks and keep up, great content.

This was my first portable in 1986/1987 and I believe my third computer. I taught myself how to type on that keyboard.

Yep! I was the Y2K engineer at my company as well. Report after report, letter after letter, cert. after cert., we're good!

Interestingly enough we are closer now to the Y2038 problem than the Y2k problem.

Nice result....destroying the EEVBlog curse....Nice

Have not watched the repair yet, but the first glance at the fault reminds me of my osborne 1, which does almost the same thing vertically where it doubled up. I'm thinking a stuck address bit

I had one but it broke many years ago, wish I still had it.

The erroneous picture data seemed to be shifted a pixel or two compared to what a pure mirror would be. That would suggest a clock gating pin was not working properly, and that's exactly what the problem was.

Hard to believe that you could do so much with so little back then. TRS-80 Model III was my first