I have an HP OfficeJet 8600 that won't power up. First it wouldn't turn off, but after doing a standard partial reset described on several websites, it now refuses to turn on. Took the CMOS battery out, verified it was good with a multi-meter, and had it out a good 45 minutes, so anything that can be reset/cleared by removing it for a few minutes definitely was.
Took the power supply out to meter it, and that's where my confusion begins. If you look at the label on the PS in the attached image, you'll see that it accepts anything from 100 to 240 volts AC and puts out either 32v DC or 12v DC. The power supply connects to the printer's mobo with a 3-pin molex connector, and its pin config is diagrammed on the label (top right corner). It shows both voltages being delivered on the right pin, ground on the middle pin, and a crescent (sleep mode?) on the left pin.
This would make sense to me if each voltage was delivered on a separate pin, but I wasn't aware you could have more than one on a single pin, which apparently is the case here. When I meter the pins, I get 32.5v across right pin and ground (middle). I get 30.3v across the right pin and the crescent (left) pin. I get 2.2v across the crescent (left) and ground (middle). I don't get 12v anywhere.
Does this make sense to anybody, and if so, can you explain to me how it works? I don't think I can declare my PS good or bad w/o first testing the 12v path to see what it reads, but how to I do that?
Thanks,
lunchbeast
Best Answer
Per testing on https://newscrewdriver.com/2019/04/03/hp-inkjet-printer-power-supply-for-nec-vsl0010-a-vfd/ the usage for a similar HP supply with the same labeling suggests that you simply ground the pin with moon symbol to switch the Voltage out pin from on/32V to standby/12V.
As Tom suggested in the comments, a small resistor of 1k or 4.7k or so is better than just shorting to ground.
Your supply may be different so take this as a general hint.