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Tandy 1000 troubles

PS2it

PS2it

Experienced Member
Joined
Mar 2, 2016
Messages
105
Location
Central WI, USA
I finally found my first Tandy (other than my 1500HD)! But of course, it didn't come without its problems :rolleyes:.

It's actually a pretty decent looking machine, came with a matching CM-11 monitor, keyboard, plus a few decent expansion cards (hard card, RS-232/RAM, 1200 baud TANDY modem).

However, this is what it does upon flipping the power switch (interestingly enough, that video is my 1000, but uploaded by someone else. I'm pretty sure this thing went through 2 owners until I bought it, and judging by the upload date I'd venture to guess neither owned it very long).

Anyway, I'm not really sure what would cause this, I did reseat everything on the motherboard. So I was hoping someone might know what the problem could be.

Let me know!
Thanks!


PS2it
 
The motherboard is stuck in a reset loop. When you apply power to it, the sound chip tends to start generating random noises, so one of the first things the CPU does when it initializes is to send the command to silence the sound chip. Thus it is normal to sometimes hear a brief blip of sound from the speaker when you first turn the switch on. But if the sound continues, that means the CPU is not initializing.
 
What would you recommend as a fix? Being that the CPU isn't initializing, I'd assume something like the (BIOS?) would be causing the problem?

Thanks!
 
Pull all the cards, read the tvdog archive site and double check the dip switches. Also Notes and Jumpers from Tandy is on the internet so you can find that and verify things are configured.

That will at least rule out a bad card, or bad switch/jumper setting.

Then RAM would be the next thing to check since its easily removed.

Yeah the BIOS could be bad, but other things can cause a reset loop. Not sure its easily found in image format to burn either if so.
 
I did previously pull the RAM and all the cards, and that didn’t seem to make a difference.

Thanks for the suggestions! I’ll report back with the results!

PS2it
 
Well I checked everything over (few jumpers), everything looked like it should, so I guess I'm back to square one. To make things worse, when I tested the WD93028-? (there is no X after the dash) on the hard card, something definitely went wrong. It started to make a burning smell shortly after plugging it into an ATX power supply. So I guess now I've got a XT IDE hard card w/o a hard drive. But as long as I can get the Tandy itself working, I can figure out something else as a storage solution.
 
You could probably check the hard drive's electronics just in case the component-in-question that burned can still be identified and replaced.
 
T-Squared said:
You could probably check the hard drive's electronics just in case the component-in-question that burned can still be identified and replaced.
Click to expand...

The hard drive board doesn't appear to have any damage to it, so I guess I wouldn't know where to start. I suppose I could find a new board for it, but I'd be worried that something inside might have been messed up.

EDIT: I checked the hard drive once more and found that 3 traces in the ribbon cable that leads to the heads were cut. It doesn't look like a repair job I'd like to do, considering the size of the cable. So I guess I'll have to find another.
 
Last edited:
PS2it said:
The hard drive board doesn't appear to have any damage to it, so I guess I wouldn't know where to start. I suppose I could find a new board for it, but I'd be worried that something inside might have been messed up.

EDIT: I checked the hard drive once more and found that 3 traces in the ribbon cable that leads to the heads were cut. It doesn't look like a repair job I'd like to do, considering the size of the cable. So I guess I'll have to find another.
Click to expand...

If the consensus is a stuck reset loop, have you actually checked that the reset button is OK? It could be jammed or damaged.
 
In the video, and when actually pushing it, it only cuts the sound until it's released. So it can't be the reset button.
 
You have a component-level failure on the board. You need to open the computer, take out the motherboard, and see if you can visually find the damage (like a leaked battery or capacitor) as a starting point.
 
I've actually had the machine opened and fully disassembled a few times, there isn't really anything noticable wrong with anything. At this point I'm thinking it's the BIOS.
 
PS2it said:
I've actually had the machine opened and fully disassembled a few times, there isn't really anything noticable wrong with anything. At this point I'm thinking it's the BIOS.
Click to expand...

pull it apart, get us some nice bright clear pictures.
 
FWIW, when I recently powered on my original Tandy 1000 after at least five years in storage, it did exactly what the OP's one did, the first three times I flipped the switch. But on the fourth try, it booted up and ever since it has worked perfectly. Maybe some capacitors in the power supply reformed enough for it to work? :confused:
 
Thanks for the replies and the link! I'll go through the board, test the voltages and check the joints on the board. Hopefully, I can get this thing up and running soon.
 
Hey, is this from the Facebook thread I sent over here about the sound not shutting off? :)

I'd start testing with the things you can test... the power supply being the first. If the PSU is off, then it'll mess up all kinds of stuff if one of the rails is not working. The technical manual quoted earlier also can give you some guidance.

I would also watch on eBay for a Tandy 1000 motherboard, as those pop up from time to time, to drop into the system if all else fails.

If you were near Atlanta, we have a group that meets monthly that looks at stuff like this. We've done all kind of stuff, soldered, let the magic smoke out, you name it.
 
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