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Trying to revive a TSR-80 Model III

J

jairo_lopez

New Member
Joined
Oct 6, 2011
Messages
6
Hi,

I own a Model III that belonged to my father (he is doctor and used the TRS-80 to store patient info). The outside is in good condition, but when I turn it on, the lower Diskette LED keep on always and spinning. On the screen only is displayer "@{".
photo (1).JPGphoto.jpg

Any suggestions what may be the problem and how to solve it?

It also came if a bunch of diskettes but I have not had the chance to test them because of the error. On of those should be the system diskette.
 
Thanks for your response. Unfortunately I don't have the skills and tools to fix it. What a shame. I really was looking forward to start it again.
 
Don't give up so easily!

I didn't know how to solder until I tried. Now I have put together things like the XT-IDE ISA board. It's worth it to learn how and to fix it. Grab yourself a soldering iron, solder, a multimeter, and have fun!
 
Thanks for the motivation. I'll try to remember my College courses several years ago and give it a try. I'll come back with the results
 
Half the hobby is learning. and besides, it's already broken, so you can't break it much more, and there's always replacement parts.

Believe me, I have broken my fair share of stuff trying to fix the original problem. It pays off at the end though. The satisfaction of it working perfectly after pouring blood, sweat, and tears into it is fantastic. You're also saving a piece of computer history!
 
Working M3 motherboards come up on eBay fairly regularly for around $20-$30 and postage to Colombia would be about the same. They are easy to replace, I can do them in about 10 min, so I suppose an inexperienced person would take about 1/2hr.

Ian.
 
If you learn how to use a voltmeter (dead easy!, try testing first with a battery), you can easily check the RAM voltages. Look at the 4416 pinout:

200px4116pinoutsvg.png


You must put the common/negative/black pole on GND (pin 16) and test with the positive/red pole the following on every RAM IC:

Vbb (pin 1) : -5VDC
Vcc (pin 9) : +5VDC
Vdd (pin 8) : +12VDC

Of course with the machine turned on. Take a look at where you put your fingers!.

The Tezza's tutorial already pointed out is gold!
 
Where I'd start if I were in an out-of-the way place, is to open the unit up, vacuum it out and then re-seat any socketed ICs, and make sure that all connectors are firmly seated.

Sometimes, this will clear a lot of problems up. Things getting moved about for more than 20 years often results in loose components.

If that accomplishes nothing, then it's time to get serious.
 
TRS-Ian said:
Working M3 motherboards come up on eBay fairly regularly for around $20-$30 and postage to Colombia would be about the same.
Ian.
Click to expand...

Yeah, there's a crap-shoot.

"Working the last time they were used" or "pulled from a working unit" with no pictures of the actual board working. I'd buy one of those. Actually, since I can fix them even if they are dead, it's not so bad for me, but, you might end up with TWO non-working boards.
 
Off topic I know, but I would be curious to learn around what years your father used this machine?
Sounds like he was well ahead of his time? I don't remember seeing computers in my doctor's office until well into the 90s.

Good luck with your project!
If you have the inclination, and access to a radio shack, or like supplier, or even amazon.com, there are a couple of books I would recommend.
I can't remember the exact titles right now, but back in the 80s radio shack had some good ones, one was something like "Basic Electronics" and another something like "Basic Computer Architecture", quick reads and easy to go through, even for a beginner.
Those a multimeter and a soldering iron, and you are in business!

Buenos suerte!
 
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