HP-19c continuing

[teenix]

I can't help much because I don't own one, but 6.2V on pin#6 would suggest that the printer strobe circuit is not working. The 4.2V on the other 19C would be more likely as the voltage here is a square wave to control the print intensity of the print heads.

If the vinegar bath was the entire circuit board, then perhaps the vinegar got inside the trimmer resistor that adjusts the print intensity and has corrupted its resistance.

I would check the circuit board tracks and connections closely to see that any corrosion and the vinegar has not degraded them.

From what I can see of the circuit, the other voltages appear to be ok.

cheers

Tony