Well that turned out to be a pretty simple answer that I should have thought of beforehand.
The motherboard connector for datasette 2 was filthy. A quick rub down with a rubber to shine the pins up - all working fine now thanks.
I do wonder why the external ports at the back of the PET are gold plated and datasette2 is silver plated - but it's all working now thanks.
Last thing to test is the user port. I have a couple of connectors and will knock up a speaker tomorrow for Space Invaders to test it.
Colin.
Quote:
Originally Posted by ortek_service
Quote:
Originally Posted by ScottishColin
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At rest after powerup,
UC7/6 (datasette 1) - 4 v
UC7/7 (datasette 2) - 5v
Pressing play (without any LOAD commands)
UC7/6 - 0.23v
UC7/7 - 5.1v (this noticeably changes on the meter from 5v)
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That's some interesting results......
UC7/7 needs to go close to 0V to work.
- So if the Datasette on Port 2 is all OK, then there must be a break in the connection of UC7/7 from J6 (Port 2) Pin F-6.
And the prime suspects would be someone has removed one of the cassette jumper links
Or that UC7's IC socket is dodgy on pin 7.
So a bit of tracing with the DMM on continuity-test should find the fault. And hopefully, no parts need to be bought.
- Especially if you've already got some spare DIL40 sockets
(Although if UC7's socket is at fault, then may be able to make original one work for a bit, with some cleaning of that pin) |