Chromatography Forum

My 6890N's oven won't heat up. I'm following this document to try and diagnose it. I already checked the fuses and they seem fine.

http://www.ecs.umass.edu/eve/facilities ... ontrol.pdf

To test the heater coil, it says:

1. Turn the instrument power off.
2. Disconnect the oven heater leads (P3, P4) from the AC power board.
3. Use an ohmmeter to measure resistance at the connectors.

Everywhere else in the document, "connector" refers to the part attached to the board. But how does testing the circuit board test the no-longer-connected heater? I'm I actually supposed to be testing the leads?

They want you to test the ohms resistance across the heater wire coil (just like with any electrical-resistance heating system, like an electric water heater). Disconnect the end terminals, measure across the heating wire.

Infinite resistance means that there's a break in that wire; that was not uncommon back in the HP 5830/5840 days.