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

SiriusHardware · 31st Jan 2021, 7:19 pm

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?

31st Jan 2021, 7:19 pm	#407
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,569	Re: Non-working Commodore PET 3016 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?