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

Timbucus · 31st Jan 2021, 6:44 pm

The 6502 drives the buffer chip INPUT which outputs a drive on pin 16 to other chips - the stump of the pin on the buffer chip should still show something which I think is what your second trace is showing and you will note is much more like the other signals the last time you did it although still not fully low which concerned Mark.

The last trace shows that the line is pulled high by something on the motherboard when the chip is not in circuit which is strange as I was expecting something to pull it low as before the graph seemed to indicate that would happen as the line seemed to struggle to get very high.

31st Jan 2021, 6:44 pm	#403
Timbucus Octode Join Date: Mar 2019 Location: Barry, Vale of Glamorgan, Wales, UK. Posts: 1,363	Re: Non-working Commodore PET 3016 The 6502 drives the buffer chip INPUT which outputs a drive on pin 16 to other chips - the stump of the pin on the buffer chip should still show something which I think is what your second trace is showing and you will note is much more like the other signals the last time you did it although still not fully low which concerned Mark. The last trace shows that the line is pulled high by something on the motherboard when the chip is not in circuit which is strange as I was expecting something to pull it low as before the graph seemed to indicate that would happen as the line seemed to struggle to get very high.