I'm trying to repair an HP 8340A that will not turn on. The fan runs all the time so I thought I'd start with testing A62K1 (Fan Relay) but I don't readily see it on A62 (top of unit). Can someone help me with location and possibly the part number?
Thanks.
Steve
Thanks Eric.
I did try removing all the TO3 devices on the rear panel heat sink and cleaning the leads and re-installing with new pads and heat sink grease. I don't have a transistor tester or 2N5885 to try yet at this point. What's the process for getting at the sockets for these - remove the rear panel or remove A62 motherboard?
Also, I can now see A62K1 but maybe it's accessed the same way as the sockets? I also measured resistance across the LHSOT temp sensor and got about 6 k ohms - tried a heat gun on it but it never switched super low. Tried removing one wire from that - no change. The circuit description says the temp shut-down circuit will kill all the supplies except the +22 v.
Hi Steve,
Sorry this response comes so late. I need to look into my notifications settings. The relay is mounted in the right rear corner of the unit. You can see it if you remove the right side panel. It's mounted on the same side of the motherboard as the power supply filter caps. The part number is 0490-0618. It's no longer orderable. It's a 2 contact, 5A, 115VAC relay with a 24vdc coil.
As far as not powering up, a very common problem is resistance in the regulator transistor contacts, mainly the 5vdc regulator. These are the TO3 transistors mounted on the big perforated heat sink. The transistors are in sockets. My usual fix is to desolder the sockets from the motherboard and just solder the transistors in.