HP 4271B LCR Question

[Wallace Gasiewicz]

Hope this is the appropriate board for this question:
I recently rescued and repaired an HP 4271B digital LCR from a hamfest. Appears to work pretty well now.
There is a switch on the A11 board that grounds the shield of the L pot lead. Should this switch be open or closed?
I do have the service manual and am unable to find the answer to my question after a lot of reading.

The only other outer conductor that is grounded is the H Pot, all outer conductors are all isolated at the chassis mount

I am also looking to acquire or build a test fixture.

Wally

[wn1fju]

Hmm, never noticed that switch on my unit.  I suppose you could do a measurement and flick the switch to see if it has any effect.  Perhaps that will give you a clue.  I don't think it will break anything.

For test fixtures, I bought a TH26001A which is a Chinese clone of the much more expensive HP version (see photo).  Works great.  About $70 on eBay.

You might post your question on the Repair board rather than the Metrology board.

[Wallace Gasiewicz]

The switch in question is on the A11 board under the black cover inside the unit
I believe the schematic shows it closed. I suppose that I will set it there. There is very little change in readings with it closed or open

I am definately considering the TH fixtures, thanks for the recommendation.