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Old 3rd Jan 2021, 7:16 pm   #18
ScottishColin
Heptode
 
Join Date: May 2012
Location: Perth, Scotland
Posts: 656
Default Re: Non-working Commodore PET 3016

The voltages seem to take a minute or so to stabilise after powering on - does that make sense?

VR6 pins top to bottom:

+0.02v
-12.40v
-4.97v

I am using the earth screw as the earth point - I have also tested using the right end of the large capacitor and got the same answers.

The VR6 is marked LM7905CT

With regard to the PET, I bought it as a known non-worker for 50 off ebay in 2012. The case is rusty and will need attention which I'm comfortable with. It came from a shed in a garden in Dumfries.

Current fault symptoms - nothing on the screen so I find it tricky to give any more detail than that. I have three external cassette drives for when I make some progress - some of my original cassettes are also in the attachments fyi.

I attach some photos of its current state and some photos of the 2012 state.

In 2012, I cleaned the motherboard with 99% IPA to get things a little clearer.
Attached Files
File Type: zip 2012.zip (1.33 MB, 43 views)
File Type: zip MyCassettes.zip (1.13 MB, 39 views)
File Type: zip Downloads.zip (3.48 MB, 43 views)
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