This is just another FYI I ran into. Hopefully this might save someone a major headache.

I have a customer 2 hours away with a HP Designjet 4500. I forget how old it is but they've had it for quite a while. The said that they had a power outage that lasted several hours, and despite the printer being on a UPS, they got tired of the beeping so they turned the UPS off, shutting the printer off. Shouldn't hurt anything, right?

Well, once the power was restored and they turned the printer on again, it would give this 2-tone alternating alarm sound, and then 7 loud beeps. The service manual says 7 beeps means the main PCA is bad. Once I was on-site, I found if I pressed the reset button (by removing the front panel cover,) that the printer would begin to initialize, and count down from 30 to 1, and then just stop there.

In the course of troubleshooting, I removed the gamut PCI card, turned the printer on, got an error, turned it off, put the board back in, and the printer booted up and printed! Weird. Well, while it was on, I printed the error log, and at the top noticed the date and time were way off (like December 2002 or something.) This made me wonder about the CMOS battery on the main PCA. I popped it out, put a volt meter to it, and got a whopping 0.2V from the 3V battery. The customer ironically had a fresh CR2032 for their truck keyfobs.. so I popped it in, and now the printer shuts down and boots up without a problem!

TL;DR - If you get 7 beeps, check the CMOS battery on the main PCA FIRST.

Kiran