The ones I used to operate let you pick from a tray for the weird parts. So you just place the parts into the tray and the machine would work it out. You'd definitely have fun training the optical recognition system though.
@@iamdarkyoshi Oh, those AOIs are a PITA. However I don't think this would be an issue, at least not a bigger one than a second chip. 1. The index mark is a chamfered edge of the package and thus clearly visible from both sides. 2. You can still inspect the meniscus of the solder joints. 3. You can still check height and planarity of the package, you might have to add/adjust your depth reference plane though.(Not sure how that works) 3a. You could check the height of the pins instead. Incidentally I'm working on a very flat voltage regulator board (to add to a stack of button cells) and will do just that. I hope combining 0603 (maybe some 0805 )parts and a low I_Q LDO will be thin enough when put into the PCB. Fun fact: VARTA V13GA cells are exactly 11.600mm in diameter(well at least mine were).
@@simontay4851 From what I remember, the contacts on the other side (on which the zebra strips to the glass LCD itself sit) is actually gold-plated. The back might not show any gold plating anymore because it went through a wave soldering process.
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.
@@MrKillswitch88 Don't blame Y2K on the engineers. They foresaw and fixed the problem in the '70s. The hysteria and cashing in that surrounded Y2K was nothing to do with real technical problems, as the total lack of any disasters proved.
Like Dave, I was one of the Y2K Engineers at work. Some others took the easy way out and claimed that they had to replace _everything_ -- but I investigated every computer (in the equipment in the portion of the plant) I was responsible for and determined that there were no critical problems. At worst, the Artisans simply needed to date, stamp, & sign any printed reports. I wonder what has been done to "fix" the Y2038 problem? I probably won't be here then, but my children & grandchildren will be....
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.
@@imagineaworld, they sent me to Dallas/Ft Worth for 40 days of training. Lived in a hotel and went to Billy Bob's Big Texas a lot. Saw leon Russel there. lol... But the best repair story was the lady at the Fish and Wildlife office in Panama City. Kept her 8" floppies on the side of a filing cabinet with a big magnet. Couldn't figure out why the disks kept going bad. LOL!
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.
@@abpccpba I think so, it's close to the same voltage. I saw it on Adrian's Digital Basement. He does a lot of old microcomputer restorations, and he always changes out the old batteries. I think generally you also have to put a diode in because the original (might) be rechargeable, and you don't want the system to try to charge the CR2032. You should look up some stuff online about how to do it, I'm sure there's lot of resources,
@@NiHaoMike64 I'm not sure if the charging system would work as-is to just swap in a supercap, never thought about doing that. Supercaps also have a less stable voltage output over time than a battery, so that might be a consideration.
@@briangoldberg4439 I installed a supercap (actually two slightly less than super caps on parallel) in mine several years ago. Still works just fine. www.hembrow.eu/personal/necpc8201a.html
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.
I came here to say that too. I was almost certain when I saw it that the problem was solved - but then he skipped over it completely. I wonder how it went getting it back in the socket like that?
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.
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.
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.
@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)
"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.
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.
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 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.
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.
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 :)
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.
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.
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.
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.
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 :)
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...
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.
Yes, but his magnet wire repair with UV cured solder mask would be a bit less neanderthal than daves 18gauge yellow wire.. Who adds a mod wire in yellow anyway? mod wires are green FFS.. :-)
@@donvito1973 mod wire can be black or blue or red as well there no formal rule. i have see and use different colour mod wires and we usually choose colour to what its doing..
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!
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.
Have you considered something like a cheap Huion H640 for drawboard? Your demonstrations are great, it'd only be an ease of use and cosmetic improvement when using the software above all. Keep up the great videos Dave! :)
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.😁
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').
@@EEVblog Right! So I took a picture of the 20 ft. long cam shaft that controlled the 350+ micro-switches that then controlled the production machines in the place. Couldn't simply say; "no RTC " or "mechanical cam operated, Doesn't know what a date is." No, no, we're streaming video back before it was a thing!
@@EEVblog But what do you even do to a device that doesn't have an RTC in it. It doesn't even know what a date is. There's literally nothing to fix. Did you just tick a box on the report without even doing anything?
@@simontay4851 yes, we "do" nothing. We just have to demonstrate that the date doesn't effect operation. That's what "Y2K compliance" was all about. We had to know that our suppliers and vendors were going to be able to operate, and our customers demanded the same of us. Think "supply chain diagnostics" on steroids!
Y2k was a big deal at my job. As I remember, we only lost 4 computers company wide. We were in manufacturing and I.T. was not tied into production directly but there was definitely a pause and careful restart.
That kind of faultfinding was quite typical through the 80s. Wraparound and overwriting faults like that are often shorted or stuck address lines. (2^3=8). Now I’ll shut up and watch to the end. Or in this case, a CS signal derived from a module-8 source.
Was the rotted out track anywhere near that battery on any of the layers. I fixed a Apple II hard drive card for a friend that had 14+ rotten tracks from an adjacent clock card that had a battery. Loved the Bill Inside logo on the splash screen. Bloody Beaudy.
excellent trace fault repair , not many techs these days go to such level or just not capable , yep faulty display not able to repair (how many times have u heard that !! ) ps that lcd is good condition for age
At least Gates could do the Jobb. That boj looks pretty good if the through hole side has enough solder. I wouldn't try my luck changing it. Maybe some non conductive gunk to make sure it doesn't move.
I don't think you'll ever find tin whiskers on those old systems, they used lead alloy solder. The lead inhibited the tin crystal growth. When I worked in the missile industry, we weren't allowed to use non-lead solder, or parts tinned without lead. It got to be a terrible procurement problem.
Back in the day, O knew someone who had one of these. It had great battery life UNLESS you hooked the modem to a phone line. That lack of an isolation transformer killed the batter life when the modem was connected.
@@simontay4851 It has one of the worst modems ever put in a battery-powered product, then. IIRC, 40 MINUTES run time with it connected, compared to 6-8 HOURS without it. (Or was it only 20 minutes?)
Y2K: I was in charge of a software protocol implementation of the Schlage compatible access control system. Everyone understood the "99" roll over to "00", but my manager could not understand the Schlage roll over in 2001. Originaly Schlage protocol designed in 1985 stored in 4 bit message field: 0=1985 + 15=2000, thus 2001 = 0. It worked out ok because the host ignored the date/time and address (rs485) fields of event messages (e.g. usage tag read)
Old computer tech used to be so much more understandable. Like most things todays versions are often too complicated with all the layers and such things to fix for most people.
I used to work on these back in the day at an actual tandy computer store which in canada, was originally a "radio shack computer center." I had them all, starting with the model I and later on to the III with the graphics addon and trsdos with a 10mb hdd. The model II and later the 16/b, but these were business models w 8" drives.. the model 100 was for field reporting etc, lots of them were sold to the local media and later to government and oil. Bill Gates was/is a thief.. the rom basic was from micro$oft tho, but everything else he pinched from smart people like gary kildall. I lived in the pacific northwest at the time, when bill was the "rich guy" at the end of the street. Early computing was really cool! I loved going to swap meets and exchanging parts and that's really where it all began. Awesome to see one of these old units getting worked over and came out on top. Cheers man!
My m100 was having similar problems. Weird garbage on the upper left corner of the screen. I stopped using Eneloop rechargeable batteries and switched to alkaline batteries, and I haven't had a problem since.
24:56 There does seem to be a strip flapping around in the breeze / strip lifted on the main board side of the ribbon cable. At the bottom near your thumb. Clearly visible pointing away from the ribbon cable at 24:59
We also had Tandy in the Netherlands. That was my first experience with electronic components sold in those blister packs glued on light blue cardboard. I'm still using the solar powered Tandy scientific calculator EC-4014 here at work. It has a hexadecimal mode and no batteries!
