So I’ve got my TV Typewriter ‘mainframe’ parts install underway. I’ve got molex connectors, caps, diodes, resistors — the whole nine yards. I decide to put the board up against a light to check for any trace ‘bleeding’ or accidental solder bridges and then:
Not good. Not good at all!
This is something any homebrew PCB maker should check before proceeding. I had been fooled — from topside, the copper obscures the tiny pinholes visible here. Since these pinholes look like the pattern of pixels in a magazine photograph, I’m guessing not enough toner was deposited to fully protect them from the etchant.
Interestingly, the traces all test good on the ohmmeter. I’m tempted to carry on – but this state of affairs really bothers me. More experienced hands warn it will eventually fail. So I decide to switch to the second mainframe board I made — that one passes the backlight test handily. I’ll wipe the black silksreening off it, clean it up, check it, and transfer everything over. Thankfully the mainframe doesn’t have too many parts installed!