UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Non-working Commodore PET 3016

SiriusHardware · 22nd Apr 2021, 11:02 pm

They may have been intended to be jumpers like the ones commonly seen on PC cards and PC motherboards, but maybe someone realised that just offered more opportunities to mess things up so they started hard-linking them in a fixed configuration at the build stage.

Plug a datasette into cassette port 2 and look again at the voltage on cassette port 2 pin C-3. I suspect that variable high voltage you are seeing there will vanish when there is a load connected to pin C-3.

You may also find that the voltage on pin D-4 (CASS READ) will be different when you do have a datasette plugged in / don't have a datasette plugged in.

With a datasette plugged into port 2, what voltage / logic level do you see on UC5 pin 14...

-When cassette port 2 is idle (not doing anything)?
-When cassette port 2 is trying to load something?

A reminder - do not connect anything or disconnect anything while the PET is turned on.

22nd Apr 2021, 11:02 pm	#1727
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,586	Re: Non-working Commodore PET 3016 They may have been intended to be jumpers like the ones commonly seen on PC cards and PC motherboards, but maybe someone realised that just offered more opportunities to mess things up so they started hard-linking them in a fixed configuration at the build stage. Plug a datasette into cassette port 2 and look again at the voltage on cassette port 2 pin C-3. I suspect that variable high voltage you are seeing there will vanish when there is a load connected to pin C-3. You may also find that the voltage on pin D-4 (CASS READ) will be different when you do have a datasette plugged in / don't have a datasette plugged in. With a datasette plugged into port 2, what voltage / logic level do you see on UC5 pin 14... -When cassette port 2 is idle (not doing anything)? -When cassette port 2 is trying to load something? A reminder - do not connect anything or disconnect anything while the PET is turned on.