HP82143A Repair - Buzzing While Powered On

[cesarb94]

Hello,

So I have an 82143A that currently powers on and is recognized by the calculator when accessing CAT2.

The problem is that when it is powered on there is an audible buzzing sound coming from the power supply circuit at all times. Also, when I try to print something from the calculator, or hit the paper advance key, another sound is emitted by the motor for a brief moment, stops, and then the message "Printer Error" appears on the calculator screen. The motor does not move at all when this happens.

I've been running the printer with a set of NiMh AA batteries, since I'm still waiting for a refurbished pack to arrive. Therefore I do not know if this is a problem with the printer itself, or the method I'm using to power it up.

I've found the service manual. I'll probably start probing around, but if anyone had a similar issue or have a guess on where to start looking, I appreciate any information.

Thanks in advance.