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Tandy TRS-80 Power Supply

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richarjo

Experienced Member
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Jun 6, 2022
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Tasmania Australia
I bought an external Tandy TRS-80 230v power supply from the UK. It is in a steel case unlike the US versions for the model 1 TRS-80 but has the Tandy TRS-80 label embossed on the top of the case. It has a white output cable and polished steel din plug; the power cable is quite short. I'm trying to figure if it's for a model 1. I measured the output on the DIn plug with a meter. Pins 1+3 = 22.6v AC and pins 2+4 = 9.9v DC. Seemingly pin 1 or 3 to pin 4 is 14.xV DC. - This may be erroneous as the pins are specified AC and DC respectively.
These are not the voltages mentioned on Ira Kings' TRS80.com. (15-17v AC and 19-21v DC) Is it a model 1 psu or a different model?
 

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The DC voltage is used to generate the 12v DC. So if you're getting 9.9v DC, the TRS won't be able to convert that to 12v DC. Can you double-check your pins with the ones listed here?
Can you also please post a photo of the bottom of your power supply?
 
Thanks for the photo! It is indeed a Model 1 power supply. If the DC voltage is indeed around 10v, then my guess is that one of the diodes inside died. You should be able to drill out those rivets and take the bottom cover off to get access to the two diodes inside.
 
Ok Thanks. My idea is to swap over the current 110v packs running on a 240v step down converter. So I will have to find another matching 240v pack so both go in the EI. That leaves me with finding a 240v transformer for the mini-disk which is also 110v. I'm umming about it as I have a nice Radio Shack filtered power board that the system components are powered by and really is ok running from the converter unit.
 
richarjo said:
Slightly off topic but did your TRS-80 diskdefs for Greaseweazle ever get implemented? I couldn't tell if the coding had been done for the TRS-80 IDAM format changes etc.
Click to expand...
For TRSDOS M1 35T and 40T, yes (see thread here), but I have not gone back to my M1 project yet. Currently trying to work, basically, on one project at a time. Currently working on an enclosure for a SN-GCJA5 particulate matter sensor w/Teensy. I did that so long ago (breadboard/programing), it almost feels like a retro project.
 
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