Author Topic: HP 3466A DMM measurement kinda unstable/never settles  (Read 696 times)

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Online kblueTopic starter

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HP 3466A DMM measurement kinda unstable/never settles
« on: May 05, 2023, 01:09:48 am »
Hello and greetings from Germany!

Mayhaps someone here can help me with a little problem (i do hope its just a little thing :D ).

The problem shows as follows: If I switch the HP 3466A on and measure immediately a 10 V DC source, the HP 3466A shows me pretty much exactly +/- 10 V. If I leave this source connected to the HP 3466A, it can be observed how the reading keeps dropping and seemingly never comes to a stop. After a few minutes, for example, it reads 9.499 V and continues to drop, albeit at an increasingly slower rate. Other DMMs running in parallel stop at +/- 10 V (as expected).

The HP 3466A is still completely untouched (all original) and comes with the battery pack. This battery pack is also still connected, even though it can no longer hold a charge.

Thanks for any advice!
 

Offline wn1fju

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Re: HP 3466A DMM measurement kinda unstable/never settles
« Reply #1 on: May 05, 2023, 11:57:59 am »
You can try two things:

1) Remove the battery pack and charger board.  Solder a small jumper wire (JM700 in the schematic) to make the 3466A run solely off of AC power.

2) Squirt contact cleaner into all the pushbutton switches and exercise them vigorously.  On my unit, the switches were pretty well sealed and I had to carefully drill small holes into them in order to get the cleaner fluid inside.
 
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Online kblueTopic starter

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Re: HP 3466A DMM measurement kinda unstable/never settles
« Reply #2 on: May 05, 2023, 04:25:59 pm »
Hello there!

I was sure I had cleaned the unit's switches. I guess I had forgotten about it when the unit came into my possession months ago.

Thank you so much! The two hints were spot on!
 


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