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My New Model Iii

C

Computer Collector

Experienced Member
Joined
Jan 22, 2005
Messages
283
Today I went to a thrift shop and was surprised to see a model III for 5 bucks. It was actually quite expensive for how it looks. it is in horrid condition, with dust everywhere, its filthy. the silver paint is rubbed off in many places, and its just a discusting looking thing. (my model 4 which ive had is beautiful)

anyway, when i turn it on, basic doesnt come up, like on my model 4. On my model 4, if i hold down break and turn it on, i get basic. Im not sure if it works. Is this normal for a model 3? If so, Im going to assume the best, take this beast apart, clean everything down real good, repaint the housing (carefully) and fix it up. If not, Im going to use it for scrap parts for my model 4. Im scared to use any of my disks on this thing. It sounds like it needs oil in those drives real bad and they are filthy.
 
Well, I used a disk anyway and tested the ting out. this is my conclusion:

1. the monitor works because it lights up when I turn it on.

2. the disk drives work at least somewhat because they spin.

3. The computer recognizes input from the keyboard and responds by spinning the disk drives

4. No characters will appear on the video display

5. using the floppyclean disk drive cleaner makes no changes

what do you think could be wrong? I would like to fix it up, but I might end up having to put it on the side of the road, and I would rather not do that to this antique.
 
Check the output from the power supply with a meter (a common source of trouble). The values for each pin should be screened on the board next to the connector.

--T
 
You need a system disk to fire up the model 3. The bottom drive is "0" where the system disk is inserted. Hope this helps.
 
To start up your TRS 80 model 3. The entire system should be off and disk drives empty. Turn on computer. Put system disk in drive 0 (bottom drive). Press the reset button. The system will initialize and TRSDOS will take control. To start disc basic type BASIC then enter. Press enter three times. The disk basic start up message will appearfollowed by the ready prompt. The computer is now ready for use. Hope this helps you get the model 3 up and running.
 
I believe you can bypass the disk boot by holding down the break or hitting shift break to get to a ready prompt. Something like that. I'd have to set up my III to verify. I am pretty sure that there is a way, even if I am wrong about how exactly to do it.
 
This thing sure is a dirty old beast. I think Im going to (carefully) remove the video display and replace it with a small windows based monitor so I can basically turn the whole thing into a monitor for XP that looks like a TRS-80. That should be a real cool poject! What part of the monitor is the part I shouldnt touch? how many volts is in it?
Normally I would never do this to a vintage product, but since it looks like it was a in a war, I dont have a problem with it this time. Nevertheless, if I do do it, I will have an extra TRS-80 video display available for someone who needs the part.
As for replacing the power supply, I dont think I want to go that route. Although Im not familiar with how to work on computers this old, from the looks of it, the power supply is the hugest computer power supply I ever saw, as it takes up the whole back of the unit. replacing it may be a bit complicated, and then the drives are so filthy, Id be surpised if they even worked right. the red lights dont even stay on when I try to load a disk.
Basically, this one doesnt deserve a nice new part.
 
Stay away from the big red wire attached to the back of the CRT if you don't know how to safely short it out. I mean, it's only about 20,000 volts, but still...

--T
 
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Most of the damage on shocks like those are in the violent body reactions to them. I like the old tech tip. Keep one hand in your pocket. The TRS mod1 monitors were notoriously dangerous because of it's grounding.

Lawrence
 
This project turned out to be a failure because my smallest monitor turned out to be way too huge for this! So instead Im just going to sell some parts in the for sale section. Im selling the keboard, video diplay, and housing. If nobody buys them soon, they get trashed because I dont have room for "space junk" like this.
Overall, although it was a failure, the project was fun and educational. I found out that the thing in the back was not the power supply, but the motherboard! apparently there are 2 power supplys. The Tanden disk drives Im going to keep and experiment with on my model 4 some day.
Ive got to tell you, I just HATE to throw away these parts, so if you need housing or whatever, let me know. Otherwise, a tear will drip from my eye as I place these items in the garbage on the side of the road :(
 
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