Howdy Y'all,
I'm working on repairing a broken HP 4277A LCZ meter I picked up a few weeks ago and am 99% sure I have narrowed down the problem to this sub-board on the main power supply assembly. The part number in the service manual is 1813-0255 and there is practically zero information on the internet about the sub-assembly. It consists of a 16 pin DIP, 3 SOT-23 components, and a few jumpers and capacitors. I have identified the DIP as a NEC uPC1042C. I am pretty sure about the SOT23's but not 100%. The SOT23's are marked as A3, Y24, and L5. I believe these three parts to be a 1SS181 diode, 2SA1461 PNP, and a 2SC1623-L5 NPN respectively. It also appears to be using some kind of ceramic substrate material instead of something like FR-4, something I have actually not seen before.
Has anyone here replaced this component before or worked on a piece of equipment with a faulty one of these? From what I can find is there are several pieces of equipment from this era of HP equipment that use this subassembly.