CBM 8032, nothing on screen

That is very odd... In such monitors, the high voltages (includign the EHT for the CRT, of about 12kV) come from the flyback transformer in the horizontal output stage [1]. So if you have high votlages, the horizontal section must be working. In qhich case you would get a line, not a dot. OK, there could be a problem with the yoke or coupling compoents, but it's very unlikely [1] There are a very few exceptions to this, but the PETs are not among them. In any case, checkign the CRT votlages will give you more of an idea as to waht is going on. Do you have a logic probe? I found this to be one of the msot useful instruemns for quick testing. I only stopped using it when I got a LogicDart :-) You really do need to check the signals from the motherbord to the monitor. It would help a lot to know that the motherboard was trying to display something. It works soemthimes, not very often Basically, uyu are hoping that either hte piggypacked IC will drive the signal harder than the one already on the board (and thus override it) or that the IC on the board has failed in a way that it produces no outputs, so Again the piggybacked one is all that matters. Needless to say this is not always the case. I am very old-fashioned in my methods of troubleshooting, in that I make measurements, look at signals, etc, before I change _anything_. On the other hand,. it works for me. Time and again. THis sounds like a motherboard problem. I think you are goign to need something other than a mltimeter. I know that _I_ would start my checkign the following : 1) Is the CPU running, is it accessing memroy at all 2) What ROM(s) are being selected, does that make any sesne 3) Is the RAM control circuit working at all, are RAS/ and CAS/ being asserted? 4) Has the CRT controller been initialised? Do HSync and VSync look sensible. 5) What is going on in the video circuit? Is the video RAM being read out, is there activity rounf the character generator ROM, is the video shift register being loaded? -tony