31st Jan 2021, 7:35 pm
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#411
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Octode
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 1,364
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Re: Non-working Commodore PET 3016
Quote:
Originally Posted by ScottishColin
Quote:
Originally Posted by SiriusHardware
On following BA10 out of the UB3 buffer I find that it appears to go to UE5 (Only) in the RAM area (circuit sheet 5) and UD6, UD7, UD8, UD9 in the ROM area (circuit sheet 4).
While UE5 is soldered I believe all of the UD6-UD9 ICs are in sockets, so how about we temporarily reinstate the UB3 pin 16 connection and remove UD6, UD7, UD8, UD9, taking careful note of where each one goes, then power on and see if the output from UB3 pin 16 looks distressed / looks OK?
If it looks OK, replace UD6 through UD9 one at a time, each time checking to see if the most recently inserted IC is causing the output on UB3 pin 16 to look distressed?
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Ok - remove UD6, UD7, UD8 and UD9 from their sockets. Reinstate UB3/16 and test/record the signal on UB3/16.
Then reinstate the ICs one at a time to see if it affects the UB3/16 signal.
That right? |
Yes this seems the best approach then it could be one of the other two chips and we can perhaps eliminate them as well if it is still distressed with UD6-9 out.
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