No picture or sound, sometimes steady tone or very garbled pic.
I shorted the power switch for now.
Power supply is 12.2v, 4.9v, -5.1v.
Sound IC pin 7(output) is normally quite so BIOS seems to be loading most of the time.
CPU seems to be partially running. Reset cap uF measured ok. Using an oscilloscope I found the CPU address line signals to be 3.3v p-p. Shouldn't they be 5v p-p like other CPU lines? CPU Vcc is 4.9v.
Some of the 4116 IC's where nearly too hot to touch so I just removed them all, will probably replace them with 5v, to check if one or more were loading down the Z80. It made no difference.
I'm an electronic/software technician but have no experience with CV. Unit is in fair shape and untouched, till now. Doing a lot of reading here. Wondering what makes sense to do next. Appreciate any help.