Is it possible the absence of the reset switch is holding the machine in a reset state (as in its an NC switch, and pressing it interrupts a pullup circuit which normally holds it out of reset. Thus you have an open circuit on the "run" signal)
@hrford
2 жыл бұрын
My thoughts too, old computers and embedded systems ran like this either to save money or to fail safe, i.e. no control panel = no run time!
@Eyetrauma
2 жыл бұрын
27:57 Doctor, come quick, Adrian’s having his bubble wrap delusion again!
@Dave5281968
2 жыл бұрын
The fails lead to diagnostics that lead to understanding and insights that lead to wins. This type of video is great to see. Now I'm anxiously awaiting the diagnostic and repair video!
@bobvines00
2 жыл бұрын
Ditto!
@BlackEpyon
2 жыл бұрын
Time to whip out the logic analyzer and see if anybody's home.
@MatroxMillennium
2 жыл бұрын
You are so much more patient than I am -- If something looks okay after a quick visual I usually plug it right in and just watch for smoke, haha.
@HighestRank
2 жыл бұрын
Retired Variac liked this comment.
@twogitsinacar4811
2 жыл бұрын
Run it up on a Variac without any load
@csbruce
2 жыл бұрын
5:12 Never noticed before - multimeter model "121GW". Great Scott!
@jeremiefaucher-goulet3365
2 жыл бұрын
Yes, I have the same one. Many youtubers bought it from Dave Jones like Adrian. It's a really great multimeter.
@Putersdcat
2 жыл бұрын
For the next time you encounter surface rust on the big steal parts that have that greenish gold finish, goto a marine shop, I’m sure their are plenty in Portland, and grab some Zinc Chromate Primer ;-)
@GabrielWehrle
2 жыл бұрын
Adrian, I just picked up a Model II myself a few weeks ago and stumbled across this series. It's been super informative (especially the last video) as I try to get my machine booting again. I picked up my machine from a friend of a friend who had it sitting in his barn for the last few decades, and it's in mint condition! After reseating a few connectors, the machine came right on! I've been using the last video you made as guidance to get a bootable floppy made, but I've had no luck with getting my DOS machine to write to the 8" disk yet. I'm excited to see the process as you get your machine running again!
@Lee_Adamson_OCF
2 жыл бұрын
I had the same bad solder joints on my PSU as well. If I recall correctly, you have the older style PSU, which may not be beefy enough if you want to add a MC68000 subsystem and run Xenix.
@binarydinosaurs
2 жыл бұрын
I too hate that first powerup moment. Prior to this the machine is Schroedinger's puzzle, you can put weeks into restoring and cleaning and things and it could be working perfectly at that point. Stuff can go wrong so very quickly when you hit the switch for the first time though. I recently worked on the only known Positron 9000 (1982, 6809 CPU) in existence after it had lived in a wet shed for decades and been chewed by rodents - some of the chips had disintegrated. Much cleaning, socket replacement, chip replacement, new PSU. Heart was in my mouth when I powered it up for the first time and..... nothing. Excellent video, thankyou for showing this hobby isn't all success :) Cheers, Adrian (Binary Dinosaurs)
@wolvenar
2 жыл бұрын
I would love to see something on this system. The progress you make etc
@jonathankent5898
2 жыл бұрын
I just found your channel. My old C64 has sat dormant in my garage for nearly 30 years. I've been wanting to resurrect it for about a month now. Thanks to your advice from your C64 videos, it's now back up and running!
@custardo
2 жыл бұрын
That chassis is cadmium plated, which means sanding and sandblasting is a health hazard. Usually to remove cadmium plating, the parts are submerged in an ammonium nitrate solution but i have no idea if this is something you can do safely at home.
@Morinaka25
2 жыл бұрын
I was to comment this as well when i saw it, cadmium is extreme toxic, you do not want to be sanding this and inhaling it or getting it on your skin.
@herrbonk3635
2 жыл бұрын
How can one see whether it is cadmium plated or not? The metal looks a little like ordinary brass to me (if that's the English word for mässing), and certainly like materials I have drilled into!
@Morinaka25
2 жыл бұрын
@@herrbonk3635 Brass is a solid colour, cadmium plating is a yelllow/pinkish type colour, with an almost rainbow sheen to it. I'd recommend just looking up photos of cadmium plating on google images for a better idea of what it looks like, but in person you wouldn't mistake brass for cadmium plating.
@herrbonk3635
2 жыл бұрын
@@Morinaka25 Ok, thanks! I belive that material is pretty common in computers, isn't it? I think I understand what you mean by rainbow sheen. But still, how do you really know for sure it's kadmium, and not just a little more zink (less copper) in the alloy? I mean, that kind of brass is usually more yellow.
@herrbonk3635
2 жыл бұрын
@@Morinaka25 (Perhaps the simple answer is that brass is never used in computers and electronics chassis? But another natural question would be, why toxic cadmium on the surface?)
@orbitingeyes2540
2 жыл бұрын
I learned programming on a Model 1 & a Model 3 back in high school. Great to see that some of these old machines still survive. I just cleaned up my slightly newer C-128. Great thinking on the connector reflow. I used to work on 14" HDDs back at Unisys in the late '80s, and those Molex connector joints were a huge problem... we routinely re-flowed them every time.
@tonanornottonull7132
2 жыл бұрын
I've got a funny feeling about that +12 rail and the video board. I think the service manual for the Model 2 says that if you see life in the CRT when checking the +12 rail then the issue will likely be the video board itself if you're not getting your sync signals.
@jameslewis2635
2 жыл бұрын
Nice work getting this far on such a complicated machine. Honestly, while I am pretty confident working on most home computers from the late 80's and onwards, the TRS-80 would just confuse the hell out of me. Rather than trying to replace all those chips that look a bit dodgy off the bat I would try sanding down the legs and using de-oxit for a start and then maybe replacing the sockets if they are looking bad. It's the kind of thing that can't hurt at this stage as if they don't work with that, you were going to replace them anyway.
@winstonsmith478
2 жыл бұрын
Because of the vibrations from the 8" drive, those glue tacked mounting bolts, and how hard they were to get out, I suspect they used Loctite on them.
@Nas_Atlas
2 жыл бұрын
Adrian should put a dab of hot glue or something
@michaelterrell
2 жыл бұрын
I scrapped one of these 20+ years ago. It appeared to be 'printer's ink', like we used on the PRC77 military radios at the factory. It is a very thick ink used to mark paper boxes, or for printing presses. We applied it with a syringe, with a blunt needle to secure screw heads on modules that had to be opened. It holds well, but cracks easily to show that something was tampered with.
@rawr51919
2 жыл бұрын
@@Nas_Atlas or use Loctite
@garthhowe297
2 жыл бұрын
Looking forward to your further troubleshooting... it's a lot harder when you don't have a working machine to swap boards with. You need a bus extender card to give you access for testing (I think).
@stevendunn264
2 жыл бұрын
I worked for the Radio Shack Computer Center in Omaha, NE in the mid 80's and the tech's always had one or two open on the benches. Brought back a lot of memories. Even then we were selling 386 and 486 machines but Model II and 16's were still used.
@graemedavidson499
2 жыл бұрын
Glad that PSU was okay! Having worked on SMPSUs for years, I’m still fearful when switching on early types. I was tensed up when you flicked that switch!
@standardnerd9840
2 жыл бұрын
28:20 Computer Chiropractic? Maybe a new computer science field? Or at least a new ASMR YT channel. 😁
@Colin_Ames
2 жыл бұрын
I always enjoy your methodical approach to the repair process. The fact that the computer didn’t work means we will get another enjoyable video in the future.
@MichaelEhling
2 жыл бұрын
26:30 It's this level of understanding and diagnosis that makes watching Adrian work so fulfilling.
@grlg2
2 жыл бұрын
I wonder if they got the idea from Ren and Stimpy's "Sugar Sod Pops" mock commercial (S2 E11) for the soda?
@Geforcefly
2 жыл бұрын
I use a remote controlled outlet for old devices I get in unknown condition, so that I can power them on and off from a distance with risking getting shocked (or worse).
@Charlesb88
2 жыл бұрын
A cheap substitute for a remote controlled outlet in this case that serves the same purpose is to plug a switched power strip into an Three prong extension cord then plug the device into the strip using a second extension cord. This allows you to switch off the power strip, switch on the device, then stand back and switch on the power strip and if needed quickly switch it off. As a temporary setup the use of multiple extension cords isn't a serious safety concern since it better then something blowing up it catching fire with you heads and/or face nearby. Note that this only works with devices with simple on/off switched not momentary pier buttons like modern desktop computers.
@Stefan_Payne
2 жыл бұрын
Time to get a Tauntek IC Tester? ;) That thing seems to be amazing for Retro Enthusiasts that repair stuff regularly.
@ObiWanBillKenobi
2 жыл бұрын
I’ve caught up with the videos in this series now. This is now like waiting for the next Star Wars movie! 🍿🤩 Some day soon I will be watching a video where this 1979 computer has been fully resurrected and lives again!
@isoguy.
2 жыл бұрын
I appreciate the time you take to make these awesome vids but can pIlease request that you don't play music over your commentary. I'm partially deaf and the mixture of voice and music excludes me from hearing what you are saying during that section of the repair video. I'm sure you don't intend to exclude partially deaf and or older people from your vids. Thank you.
@jerryspann8713
2 жыл бұрын
Why is it that when you showed those diodes, the first thought that came to mind was the 8 bit guy? This was before you mentioned his name.
@feedmyintellect
2 жыл бұрын
27:53 is where the old socketed chip chiropractic session starts. Enjoy! 😁😁😁
@justinchampion5468
2 жыл бұрын
As usual a great and fun retro-work video! Also, the grass soda made my skin crawl! I love the smell of fresh-cut grass but I can't imagine drinking it. *Mr Yuck Face*. In any case, thanks again Adrian!
@adriansdigitalbasement
2 жыл бұрын
It was shockingly better than it seemed!
@atari2600b
2 жыл бұрын
Hey I'll straight up sell you a model 4 below market rate if you ever want to drive to NorCal. I just finished scrubbing the plastics mostly & removing the rabbit piss damage & refurbed the psu but it got like 20 bodge wires (you know how trs did back then with the bulletins), the drives probably need work, & I think one of the ram chips is bad.
@stevedonkers9087
2 жыл бұрын
If the Fujitsu chips are transceivers you should just be able to breadboard them (if you can find a datasheet) and see if you can make some LEDs light up through the chip.
@TatsuZZmage
2 жыл бұрын
Only bright green soda I ever want is green river, God it's been ages
@Video_Crow
2 жыл бұрын
Every time I visit family near Chicago, they stock up on Green River, and it's all I drink while I'm there. I wish it would get wider distribution.
@BapsyGames
2 жыл бұрын
I like that Power Connector, aesthetically (and logically)... It's keyed in a nice way (2 flats on one side and 1 on the other) ...And I like the shape of the 5 by 3 arrangement :-) edit* Forgot to mention... Nice Video again @Adrian :-)
@TheSimTetuChannel
2 жыл бұрын
Given your track record on tricky issues I have no doubt we'll soon learn that IT FREAKING WORKS!
@pogostix6097
2 жыл бұрын
Excellent video! It's fascinating seeing the curvy, curly, hand-drawn traces when you're so used to angular, computer-done ones. Connectors are especially prone to breaking... my wacom art tablet kinda regurgitated its USB Mini B port a little while ago. And of course it took the solder pads and contacts with it so it can't be fixed... found a workaround, I can charge the battery using a separate device so I can still get art done, but it was very alarming when it wouldn't connect/charge and when I unplugged it it just... came out with the cable.
@Azlehria
2 жыл бұрын
Is there perhaps room for a panel-mount port? If not, a last-resort repair could potentially be made by running jumper wires from a new PCB-mount port to the _other_ end of the traces, then epoxying the port to the board.
@benjaminhanke79
2 жыл бұрын
Take your time and bring it back to life, it's so satisfying to watch a repaired machine up and running. In the last ten months I watched CuriousMarc's videos where he repaird his vintage HP 9825 Desktop "calculator" after the failing power supply damaged several components. I was really happy when I saw it working again.
@JaapGinder
2 жыл бұрын
That Grass Soda... it says 'Pine sugar' on the label, so sugar... you are a diabetic, but drinking lemonade with sugar??? I'm diabetic too, with pump, so it makes me wonder. A pitty the machine isn't booting. Could it be that a keyboard must be connected?
@jumhig
2 жыл бұрын
I'm diabetic too, and it's pretty disturbing to watch a diabetic drinking soda (that isn't sugar free). Also the Haribo and other sweets are a no-no.
@JeffVanRooy
2 жыл бұрын
It says "Pure Cane Sugar" which is a marketing gimmick becoming mildly popular because so many people think the glucose & fructose in High Fructose Corn Syrup (HFCS) is somehow different (and of course, also "evil") than any other glucose & fructose found on the planet whether produced by a plant, an animal, a bacteria, or a manufacturing plant in Saskatchewan, are exactly the same molecule. Glucose is glucose, fructose is fructose no matter the source. That being said, yes it's sugar. What I find weird, which is putting it mildly, that anyone would consider a diabetic ingesting sugar "disturbing" or even think it is a big enough of a deal to mention. We can have sugar, it's all about moderation and adjusting your medication which is extremely simple to do especially if you simply plan out your once in awhile slight indulgences in advance. Though a single bottle (which contains less sugar than the daily recommended amount for diabetics) in a 24hr period likely wouldn't be enough to require much, if any, modification though this does depend on which type of diabetes and its severity. I would guess that he is Type 2 since more than 90% of diabetics are and almost certainly knows what he's doing since even children can easily manage their diabetes after learning how to do so.
@ChrisDreher
2 жыл бұрын
Cool seeing other Astec parts. They are moderately known for making RF modulators parts in old gaming consoles (example: Intellivision gaming console).
@loganjorgensen
2 жыл бұрын
Beautiful restoration on that PSU and mount. Dang that unit has got some weight to it, can see how a drop would be hard on it even though it's so sturdy. Also the editing on this video is really tight and well paced. Interesting project, the vintage stuff sure is specific often, absolutely no slack for any deviation from spec.
@midimusicforever
2 жыл бұрын
Grass soda actually sounds nice and quirky at the same time!
@tony359
2 жыл бұрын
awww - I was also hoping you'd fix it! Great video as usual though. Looking forward to the next chapter. One thing about the isolation transformer: I'm just concerned someone may think that isolation transformer = total safety. If I understand correctly, it's not. If you touch ONE cable at the time, indeed it provides isolation and safety. But if by any chance you end up grabbing BOTH neutral and phase, you get electrocuted. And the sad thing is that the house RCD won't cut the power. So it's a bit of a mixed feeling on that - and don't get me wrong, I use it myself. (Happy to be corrected if I am mistaken)
@highpath4776
2 жыл бұрын
Can you run a fuse/rcd after the isolation transformer - how would you wire it - have incoming mains distribution board - fixed isloation transformer - separate new distribution board for your electrical play room - variac into glow blub to the socket for the articles under test ?
@tony359
2 жыл бұрын
@@highpath4776 I've always wondered if I could connect an RCD AFTER the isolation transformer - would that work? I have a separate distribution board in my garage, a variac (which I never use) and my isolation transformer which feeds the lightbulbs (current limiters) and eventually the device under test. From my limited understanding on how an RCD works, installing one after the isolation tranformer should work. But I'm not 100% sure.
@rwdplz1
2 жыл бұрын
8:18 I found a bad large capacitor in, of all things, a ~1980 Tektronix 465B oscilloscope
@Teppic11
2 жыл бұрын
I've no idea how you managed to reassemble that.
@scharkalvin
2 жыл бұрын
The top slot connector might be warped without being broken. If you can find a replacement connector you can use a solder sucker to remove it and replace it.
@anthonydenn4345
2 жыл бұрын
I'm just wondering does it matter that you skipped over that first broken socket on the connector interface board.
@8_Bit
2 жыл бұрын
An 8" floppy disk has the power to make an adult look the size of a hobbit. It even works if the disk is offscreen; I saw Elijah Wood demonstrate it in a bonus feature on my The Fellowship of the Ring DVD.
@neccron9956
2 жыл бұрын
You should have High voltage (you should be able to hear the flyback) irrelevant of a video signal. You should be able to take the video out, and run it to a different monitor.
@EngineeringVignettes
2 жыл бұрын
Its a pretty simple driver board. I don't think it has a local oscillator. I believe it relies on the 15 KHz horizontal sync, from the video generator board, to drive the HOT (transformer).. from what I remember.
@crbielert
2 жыл бұрын
Just wanted to let you know that the gold coloration on the sheet metal is often a cadmium plating for corrosion inhibition. So always wear a mask when you sand it.
@projectartichoke
2 жыл бұрын
Yep, cadmium is awful stuff, it has mutagenic properties. Skin contact isn't even a great idea. When cadmium coatings corrode you wind up with cadmium salts which have very high bioavailibilty and can be absorbed through contact with skin moisture.
@mrb5217
2 жыл бұрын
How can you tell cadmium plating from yellow zinc?
@horusfalcon
2 жыл бұрын
Is FormatQM a Sydex product? I'm still using CopyQM and Teledisk at work to support ancient machine tool computers, and couldn't get through the day without them. That orange stuff looks like Torque Seal, a tamper detection lacquer.
@adamw.8579
2 жыл бұрын
If memory board has 16kbit P-MOS memory chips MUST HAVE NEGATIVE 5V! Otherwise these chips are gone. Also common failure in older Spectrum version.
@adriansdigitalbasement
2 жыл бұрын
It does but it likely has a voltage regulator on the RAM board to generate -5v from the -12v rail.
@adamw.8579
2 жыл бұрын
@@adriansdigitalbasement These two Fujitsu chips (U52 and U53) are standard 8T26A bus transceivers. Fujitsu always had own nonstandard markings.
@6581punk
2 жыл бұрын
Fixing this PSU is an Astec Challenge.
@aaronjamt
2 жыл бұрын
Quick suggestion: get a set of cheap remote controlled outlets to plug computers, monitors, isolation transformers, etc into. It makes me feel much better powering up old equipment when I can stand a few feet back with a fire extinguisher or whatever when I turn it on. I can also very quickly shut it off if I need to, even if I would normally have to reach over live power cords or bare wires to unplug it. I've also created a mini foot-pedal that allows me to hit the "off" button on the remote with my foot if something goes wrong, also very useful (especially when hands are full with the fire extinguisher).
@gpiforgoo
2 жыл бұрын
hmmm... I would rather install an emergency button, which shout down the complete power in the room. And be careful with the fire extinguisher - there are different kind, especially when high voltage electronics (like crts) are involved. I this case maybe other factors could be interesting, for example a basement with small windows. Or you want to use something that damage the stuff there at least as possible.
@video99couk
2 жыл бұрын
8:15 I had a bad mains filter capacitor on an Epson XP-55 printer. It blew the chopper transistor.
@twogitsinacar4811
2 жыл бұрын
"Replace the entire" board Rubbish, change the two large electrolytic capacitors, they will go leaky with age and their ESR might be quite high, sometimes you can reform them though, if it was me I would replace them. four of the orange ones might be a bit suspect too, but the rest of it looks to be OK
@Potts1966
2 жыл бұрын
I'm really enjoying your journey with the Model II. I did have a model 1 many years ago and the Model II was a "pie in the sky" super-machine I could never afford.
@Sloxx701
2 жыл бұрын
This will be a fun series to watch if you keep going with it, hope you do. On thing I hate about troubleshooting any type of vintage electronics that use multiple cards stacked like that is that you cant access the boards easily for proper probing without having some type of extender card to bring to board out where you can access everything. Can be a pain
@mxmaverinho8115
2 жыл бұрын
Woodgrain waterbottle, LGR approved!
@macrohard007
2 жыл бұрын
What is that under computer keyboard tray called and where can you buy one? The one that your IBM is on.
@airlink2142
2 жыл бұрын
Could have used PC 4 pin molex power connector's pins to do the testing.
@mogwaay
2 жыл бұрын
Great video and keep the faith, you'll get it up and running, Im sure if it and I'll be really interested to see the journey. This has definitely inspired me to take a look at my poorly Acorn Electron which I need to see if it's power supply board works, thanks!
@sfperalta
2 жыл бұрын
Great video series. Fun to watch the diagnostic process and the repair techniques used. Also fascinating to me because I was a TRS-80 user, Model I and Model 4. Back in 1980 I bought the base Model I (16K, cassette storage) because, frankly, it was almost half the price of the Apple ][ that I was looking at -- though the Apple ][ had color output and expansion capability in their base model, unlike the Model I. Eventually I got the Model I expansion module to bring the computer up to 48K (I think... memory is fuzzy) along with a pair of 5.25 inch floppies to round out the setup (much more usable than the cassette interface!!). Funny thing, that fancy configuration made the Model I pretty close to the same cost as a similarly configured Apple ][! The TRS-80 was a good, capable machine and there was enough technical info available for it that I was able to learn quite a bit about computer technology from using it, as well as write many useful BASIC programs to automate my life. Eventually I sold the Model I to buy Model 4P with the integrated floppy drives which could run CP/M as well as TRSDOS. Although the 4P was nominally portable, it was rather more a "luggable" like many of its contemporaries. All in all solid computers, great for learning (though I must admit, the Apple ][ would have been the better investment in the long run LOL).
@markae0
2 жыл бұрын
Thanks for the video! With the test equipment you have, you have a good chance of chasing down what is wrong. Just getting those 8 inch drives working was great, great to see.
@bloxyman22
2 жыл бұрын
I have had access to electronic recycling waste for a very long time, but I have nowhere near the knowledge like you when it comes to electronic. I found computers from the 70s, tube radios from the 40s and anything in between. Nearly all of my equipment is from recycling center current amplifier I use is a 60s kenwood ka-6100. All equipment I found I just fired up up from the get go if they were dry and not wet from rain. Guess what?? 99.9999% of the time it just works. This amp I am using now has been on 24/7 for years and even bulbs works. I have just never come across something except maybe one "modern" ampilifer that failed because of a capacitor. Even had a osbourne 1 at a time with a bunch of working software, but sadly I was dumb enough to trade it away back a long time ago.
@benhawke7231
2 жыл бұрын
🤣😂🤣😂 mowed and bottled in the USA. That is a crazy ass power supply. I wasn't aviation electronic technician in the Navy and I've never seen a power supply as crazy as this. And I've seen some crazy power supplies that were built in the 40s and 60s.
@markae0
2 жыл бұрын
So what is next? Is it the CPU and board? You looked at the screen working (it works), you looked at the drives working( they work) so the CPU and memory is next? CPU + board is all low voltage right? you can't get shocked like when working on the screen. TV tube working voltages are dangerous :)
@janklas7079
2 жыл бұрын
If you ever make a video like this again, PLEASE stop touching caps after the thing was just turned on and PLEASE keep those fingers further away from the CRT.
@karlbauer4616
2 жыл бұрын
back in 1986 i was working on the Model 2 selling it for office use to chimney sweeps in Germany, We sold some 200 of them until switching to IBM pc/at. loved the all-in-one design. will check my garage if i still have some of this stuff. hope you get your machine running soon !!
@mikep8080
2 жыл бұрын
I feel bad now that I finally tossed my working 2 models of the Tandy 1000 (one had the 1 mb mem upgrade so no floppy boot disk needed) and working TRS80. But last year I chose to finally let them move onto the big digital blue sky. Now hopefully my working Atari and Pong systems were not tossed by my mother when she moved LOL. I even gave away the trs80 binder with cassette tape storage. I had all the cassettes but 1.
@jensschroder8214
2 жыл бұрын
I think it wasn't a losing, it was only half a win.
@absalomdraconis
2 жыл бұрын
The soda is probably chlorophyll flavored (or more particularly, wheatgrass juice). The taste of "raw" chlorophyll is best described as "green", but actually doesn't taste bad... as long as you don't have it too concentrated, of course.
@waltschannel7465
2 жыл бұрын
Not the result you were hoping for, but I think you made a LOT of progress. That TRS-80 is a complicated device with a lot of potential points of failure, and was likely damaged in a drop. I think you are correct that the one connector could be a major part of the problem. I was curious why you think that boards other than the sweep board could be causing the lack of vertical and horizontal sweep. Theres a ton I don't know about the TRS80. 🙂
@BlackEpyon
2 жыл бұрын
My first concern would have been the RIFA, but that's already been replaced. Also, a note on the absence of a -5v, I don't recall any Tandy I've ever seen that had a -5v rail off the power supply, and not all of them even had it on the system bus either. At least the Tandy 1000 RSX, and probably the rest of the 1000 R series has a 7905 to provide -5v to the system bus, but so far as I know, none of the XT systems had it at all.
@johnlawson1252
2 жыл бұрын
Adrian, I just got a machine that has an MFM controller and drive. It also has a video card I do not recognize. Can you, or the community, help me. I need to find an XT to IDE and an 8 bit VGA card. I appreciate any help I can get, thanks. Also any advice is welcome, I have not fiddled with XT class machines in over 25 years!
@AnthonyRBlacker
8 ай бұрын
They put a serviceable fuse for the disk drive on that machine because the disk drive blows fuses. They don't want people taking that in for service to change a fuse that's not user serviceable so they added one externally because when they did their testing, they blew the fuse often enough to add the cost of putting that external fuse in. Also, it may be there just because back then EVERYTHING had a fuse you could change in it without opening the unit (stereo receivers, amplifiers, etc.,)
@series80
2 жыл бұрын
I remember debugging an Intel 8086-based computer (not PC compatible) many years ago. I hooked a logic analyzer to the bus and could see the instructions being executed. Luckily I had the appropriate software for the LA so I could see the instructions as assembler mnemonics rather than hex codes. Anyway I realized the machine was stuck in a loop. Looking at the code I saw that it was waiting for the screen blank signal. So I checked that signal and while it appeared on the bus, it didn't show on the I/O chip pin. So with the machine powered up I connected the pin to the bus and I heard the disk drive head moving as the machine was trying to boot. Where I am getting at is that the repair may not be as complicated as it looks. You'll need an oscilloscope for sure and a logic analyzer would be a plus.
@herauthon
2 жыл бұрын
What is your floppy- or non-floppy favo tools, utils and diagnostics wares ? i just want to expand my little list beyond: infoplus aida speedsys snooper and do you trust the PSU or is it much better to use converter cable and a new PSU for testing ? i did that - and i feel much better now :D
@vanhetgoor
Жыл бұрын
I am the proud owner of four of the boards and some cables. No drives and no critical race theory as they used to call those glass displays in the past. I don't know why they names those bulky displays so, maybe because it is black and white? Anyway, some day I am going to put things together and get me a drive. Preferable 5 and a quarter Inch, my house isn't big enough for eight inch.
@scsirob
2 жыл бұрын
You probably will not have any video until the entire system is functional. The 6845 on the video board needs initializing before it works.
@UpLateGeek
2 жыл бұрын
Interesting that those Fujitsu chips might be problematic. I was just looking at picking up some 4164 type chips, so I'll keep in mind to steer clear of those Fujitsu ones too.
@station240
2 жыл бұрын
I've seen Astec PSUs in other microcomputers with those orange capacitors. They can leak in an odd way, the electrolyte melts the rubber boot and glues the capacitor to the board. Looks fine from the outside, only when you remove one do you find the failure.
@SimonEllwood
2 жыл бұрын
Maybe add some clear sheet acrylic (Plexiglas, Perspex) over the mains connector block. Great video!
@travmanbrett5338
2 жыл бұрын
I was a radio shack repair tech back in the early 80s and worked on model II s . Just from experience I remember video problems were mostly caused by a failure of the video boards. The CRT ( cathode ray tubes) were very reliable and almost never failed . Earlier comment concerning the bad reset switch is also a possibility
@moonrock41
2 жыл бұрын
The methodical approach you've taken with this restoration is laudable, but at some point you may just have to say, "He's dead, Jim." and move on.
@jonbretro4596
2 жыл бұрын
Ask for advice on the VCF TRS-80 forum. There are some proper Model II experts there.
@AurediumRiptide
2 жыл бұрын
Dear lord the pcb of that psu made me shout ugly. But I guess its the age of the product. It was most likely analogue designed and made. Being used to tight routing by software like Ulticab myself i was a bit shocked. Thou I do understand it considering the era. And in the end; when it works it works.
@abeleski
2 жыл бұрын
Polarity matters when using the der5000??? I never knew that. Geezuz
@kins749
2 жыл бұрын
Amazing job cleaning the whole machine, great progress overall, just the small matter of the logic board!
@IvorySoul696
2 жыл бұрын
I love the idea of the food items as "breaks" in the middle of videos. It feels like a natural way to get the food items in there.
@techkev140
2 жыл бұрын
Hey, I've got some of those black and transparent amber looking nut and screw drivers. Got them in a tool set from a high street store here in the UK back in the 90's.
@allalphazerobeta8643
2 жыл бұрын
You can buy paint to look like different corrosion resistant finishes like zinc dichromate. I personal don't really care that much.
@BradinSiouxCity
2 жыл бұрын
you are one of the few people who hasn't tried chewing grass. Did you not try dumb stuff as a kid? LOL, and yes, it tastes like it smells.
@bettyjones2614
2 жыл бұрын
Wow are you not scared of electrocution? I thought CRT's really give a kick
@4Nanook
Жыл бұрын
My recommendation would be unless you're successful, don't post. Nobody wants to learn how to be unsuccessful at a restoration.
@dl8cy
2 жыл бұрын
See you in the future again, little TRS-80 Model II ... sleep well for some weeks
@darthbukowski6894
2 жыл бұрын
I’m looking at a Tandy 6000 HD right now. Not sure if it’s a good price or not.
@CobraFat2000
2 жыл бұрын
I wonder if taking a picture and mirroring it on some screen near you, so you don't have to keep flipping the unit, might be an alternative. And I've been lied to - people told me you cannot measure an electrolyte cap while it is still in the PCB connected to other components and here you are walking on water in spite of people not believing.
@jamesdye4603
2 жыл бұрын
If you can find it, try the birthday cake soda. I get my novelty soda at a place called Rocket Fizz. It's an old time candy store.
@ruediix
2 жыл бұрын
You can likely get off the shelf replacements for those card edge connectors since they are non-keyed. Likely is, of course, not a certainty, but you could try contacting some electronics supply catalogues.
@sheep1ewe
2 жыл бұрын
This is a great restoration, i try to keep my machines as original as possible, but also so they can be used as this, maybe if it has been something extremly special, like the only one in existance it had been different, but honestly all my machines are in reality less than 100$ market value and where made in large series so using rustremover and automotive protecting paint is not a problem here and will do perfect for presvering the machines for the future.
@firstname1lastname127
2 жыл бұрын
I hope you saw the earlier comment from someone about the cadmium plating on the chassis... It's better not to sand that stuff, don't breath it in or get it on your skin man... it's bad stuff.
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