UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Just got myself a commodore pet setup but not working

SiriusHardware · 10th Jun 2022, 11:28 am

While you're in the monitor looking for the glow look for any other potential physical problems (input connector on monitor PCB hanging half way off, etcetera). If all seems OK there have a look with your scope for signals on pins 3 and 6 of 7486 IC UC2 on the mainboard. These are the Horizontal and Vertical drive output signals, without which the monitor will not start up.

If you see nothing there look on pins 39 and 40 of UB13, the CRTC Controller IC.

At the moment I'm assuming that because you get that startup jingle, a good portion of the machine is actually working.

10th Jun 2022, 11:28 am	#26
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,570	Re: Just got myself a commodore pet setup but not working While you're in the monitor looking for the glow look for any other potential physical problems (input connector on monitor PCB hanging half way off, etcetera). If all seems OK there have a look with your scope for signals on pins 3 and 6 of 7486 IC UC2 on the mainboard. These are the Horizontal and Vertical drive output signals, without which the monitor will not start up. If you see nothing there look on pins 39 and 40 of UB13, the CRTC Controller IC. At the moment I'm assuming that because you get that startup jingle, a good portion of the machine is actually working.