Trash or treasure? Tandy Model TRS 80 Model 4

[rwh63]

Grabbed this from my towns electronics recycling trailer. Did not power on. Don’t know anything about these. Did some research. Last of the Z80’s. Retailed for $2k. See working ones on Ebay listed in the $500-1500 range. Worth getting into for resale potential, or back to the dump?

 

[MK500]

I highly recommend you send it to Adrian; you would bring a lot of joy to people and preserve some history, as he would almost certainly restore it to working condition.

I totally understand wanting a turn a profit though. If you decide to go that route I would recommend selling it to someone who can restore it. Most of the fun is in the restoration; but it's not that much fun if you don't have love (nostalgia) for that era machine. Learning to restore one just for resale wouldn't likely earn you a big profit; and could even be quite dangerous if you are not familiar with working around high-voltage tubes of that era.

 

[velocityg4]

Looking at sold items on eBay. I'd guess around $150-$200. Since the case looks clean. Local pickup only. You don't want to ship it

If you are willing to open it up and take pictures of the boards. To show they look good. You might get more. The more confident they are that they can rebuild it. The better the price. Knowing everything inside isn't a rusted slagheap makes a difference.

 

[sracer]

Grabbed this from my towns electronics recycling trailer. Did not power on. Don’t know anything about these. Did some research. Last of the Z80’s. Retailed for $2k. See working ones on Ebay listed in the $500-1500 range. Worth getting into for resale potential, or back to the dump?

I agree with @velocityg4 . Open it up and take a look at the insides. If the board is fried or seriously damaged, then what I would do would be to repurpose the case.... replace the CRT with an Android tablet or iPad. Replace the keyboard with a mechanical bluetooth keyboard and make it fun little retro project.

That's what I did with my original iPad 1. (ordered it day-1 that preorders were available) It now serves as the "picture tube" for a vintage TV that no longer functioned.

 

[velocityg4]

I agree with @velocityg4 . Open it up and take a look at the insides. If the board is fried or seriously damaged, then what I would do would be to repurpose the case.... replace the CRT with an Android tablet or iPad. Replace the keyboard with a mechanical bluetooth keyboard and make it fun little retro project.

That's what I did with my original iPad 1. (ordered it day-1 that preorders were available) It now serves as the "picture tube" for a vintage TV that no longer functioned.

View attachment 2062466 View attachment 2062467

Op could also just get an off the shelf LCD panel and connection kit about the right size. Then put a Raspberry Pi inside it. There's probably a way to wire up the original keyboard.

 

[Technerd108]

That looks like the computers we had at the computer lab at school in the 80’s. Lol

 

[mi7chy]

Could be something as simple as blown fuse. Although not as rare as 4D but it's worth fixing. Start here...

https://www.reddit.com/r/trs80/
https://www.reddit.com/r/Tandy/

Here's someone looking for non-working 4.

https://www.reddit.com/r/trs80/comments/x2oo0s

 

[rwh63]

I’ll open it up when I have extra time.

 

[rwh63]

Gave it a quick exterior cleaning. Looks really good.

 

[rwh63]

PICTURES!

 

[PinkyMacGodess]

Grabbed this from my towns electronics recycling trailer. Did not power on. Don’t know anything about these. Did some research. Last of the Z80’s. Retailed for $2k. See working ones on Ebay listed in the $500-1500 range. Worth getting into for resale potential, or back to the dump?

I'd start by capping it. After that, see where it leads you. I have an old Atari 800 that I will probably try to set up, see what happens. I'm sure the caps are all old and fragile, by now.

 

[rwh63]

Anything I should do before I put it back together?

I don’t do electronic repair. But maybe I can be guided to do some testing.

Like older audio gear, the issue is usually pretty simple and inexpensive, if you can do it yourself.

 

[rwh63]

Looking at sold items on eBay. I'd guess around $150-$200. Since the case looks clean. Local pickup only. You don't want to ship it

If you are willing to open it up and take pictures of the boards. To show they look good. You might get more. The more confident they are that they can rebuild it. The better the price. Knowing everything inside isn't a rusted slagheap makes a difference.

Looks like recent solds on eBay are running $300-$1000 shipped, non-running/running. Looking at pics, definitely not a slag heap!! Just dusty. Hired recapping would run several hundred. Don’t mind shipping, I have shipped similar before. Key is insurance!

 

[mi7chy]

Anything I should do before I put it back together?

I don’t do electronic repair. But maybe I can be guided to do some testing.

Like older audio gear, the issue is usually pretty simple and inexpensive, if you can do it yourself.

RIFA capacitors should be replaced right away or removed before turning on the computer since they're notorious for blowing. At least one at C2 is showing signs of cracking before blowing. Otherwise, hold down break key while turning on computer to get text display output. May have to turn up brightness dial.

Learn high voltage safety and discharging capacitors then at a minimum RIFA caps at C1, C13 and C2 should be replaced first.

https://www.make-it.ca/trs-80-model-4-power-supply/

Refer to page 114 of technical reference for checking input and output PSU voltages.

https://www.trs-80.com/wordpress/service-manuals/

 

[rwh63]

RIFA capacitors should be replaced right away or removed before turning on the computer since they're notorious for blowing. At least one at C2 is showing signs of cracking before blowing. Otherwise, hold down break key while turning on computer to get text display output. May have to turn up brightness dial.

Learn high voltage safety and discharging capacitors then at a minimum RIFA caps at C1, C13 and C2 should be replaced first.

https://www.make-it.ca/trs-80-model-4-power-supply/

Refer to page 114 of technical reference for checking input and output PSU voltages.

https://www.trs-80.com/wordpress/service-manuals/

Tried the break key technique, nothing happened.

RIFA capacitors should be replaced right away or removed before turning on the computer since they're notorious for blowing. At least one at C2 is showing signs of cracking before blowing. Otherwise, hold down break key while turning on computer to get text display output. May have to turn up brightness dial.

Learn high voltage safety and discharging capacitors then at a minimum RIFA caps at C1, C13 and C2 should be replaced first.

https://www.make-it.ca/trs-80-model-4-power-supply/

Refer to page 114 of technical reference for checking input and output PSU voltages.

https://www.trs-80.com/wordpress/service-manuals/

tried the break key technique, nothing happened.

 

[mi7chy]

Tried the break key technique, nothing happened.

Next logical step is to diagnose the two power supplies, one for mainboard and a second for CRT. Remove the RIFA filter caps to see if it's preventing the computer from turning on.

Next, check if fuse is blown then replace and retry. If fuse keeps blowing, check if any transistor is shorted which would cause it. Otherwise, verify correct input and output voltages. You'll need at least a multi-meter. Once determined what voltages are missing or out of spec you can decide if it's worthwhile to attempt to fix or replace with modern $75 mainboard PSU.

 

[rwh63]

When I had the unit opened, I did examine the two fuses (one for the monitor, one for the computer) and both looked good.

 

[rwh63]

Looking at sold items on eBay. I'd guess around $150-$200. Since the case looks clean. Local pickup only. You don't want to ship it

If you are willing to open it up and take pictures of the boards. To show they look good. You might get more. The more confident they are that they can rebuild it. The better the price. Knowing everything inside isn't a rusted slagheap makes a difference.

just to update this thread, a buyer has purchased it for $400 shipped to CA. i figure shipping and insurance will run $75-$100. i believe it weighs about 35 lbs alone.

i didn't have the time/skills to do anything with it, but did my part salvaging it and running an informative ad.

 

[velocityg4]

just to update this thread, a buyer has purchased it for $400 shipped to CA. i figure shipping and insurance will run $75-$100. i believe it weighs about 35 lbs alone.

i didn't have the time/skills to do anything with it, but did my part salvaging it and running an informative ad.

Pack it really, really well. Those old computers are fragile, generally brittle and your don’t want it to shatter during shipping.

Thick and dense packing.

 

[rwh63]

a while ago i shipped a power mac and monitor to CA, arrived safely. this is actually easier looking than that. if possible, double boxed, lots of solid packing material. need to make it immobile. then add full insurance.

 

[rwh63]

First packaging step