Author Topic: Agilent 34410A Repair  (Read 7121 times)

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Offline jfedison741

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Agilent 34410A Repair
« on: November 13, 2012, 09:07:24 pm »
Does anyone have familiarity with the repair of either the Agilent 34410A or the 34401A? I am in the process of repairing an Agilent 34410A DMM which is giving faulty readings on 2-wire ohms.  All other functions appear to be accurate and stable.

When I measure 2-wire ohms I get an offset in the reading. For example on the 100 ohm range I will get readings from 102-110 Ohms in 2-wire mode when measuring a 100 ohm resistor. This same resistor measures a stable 100.0 ohms on a known good meter. In 4-wire ohms mode, the meter under repair gives an accurate stable reading of 100.0 ohms. The current source for 2-wire ohms (100 ohm range) is a stable 1010 microamps on the faulty meter versus 1007 microamps on a known good 34401A.

Also, the 2-10 ohms offset appears to drift over time. The same behavior occurs regardless of whether the probes are connected to the front or rear terminals. Multiple sets of probes were used and all gave similar offset. On a known good meter the probe resistance was measured to be 0.2 ohms and stable; multiple probe sets were tried.  So far I have checked the relays that switch the signal paths and they appear to be ok (no offset detected across any of the closed contacts). The offset must be coming from elsewhere in the signal path.

The unit was purchased new in Nov. 2006. Agilent does not offer repair of this model, they only offer $727 swap of the faulty unit with a refurbished unit.

Any help/advice would be much apprecaited!
Jeff
 

Offline saturation

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Re: Agilent 34410A Repair
« Reply #1 on: November 20, 2012, 09:24:39 pm »
May I suggest you post this request to the HP-agilent yahoogroup, there are more device specific experts there.  Both units are still in the Agilent catalog, so I'm surprised they won't repair it, but only swap it.

http://tech.groups.yahoo.com/group/hp_agilent_equipment/
Best Wishes,

 Saturation
 

Offline jfedison741

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Re: Agilent 34410A Repair
« Reply #2 on: November 20, 2012, 10:38:16 pm »
May I suggest you post this request to the HP-agilent yahoogroup, there are more device specific experts there.  Both units are still in the Agilent catalog, so I'm surprised they won't repair it, but only swap it.

http://tech.groups.yahoo.com/group/hp_agilent_equipment/

Thanks for the that link,  I will copy my post there.
Best regards.
 

Offline free_electron

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Re: Agilent 34410A Repair
« Reply #3 on: November 21, 2012, 12:25:12 am »
check the transistor ladder.
Professional Electron Wrangler.
Any comments, or points of view expressed, are my own and not endorsed , induced or compensated by my employer(s).
 

Online mzacharias

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Re: Agilent 34410A Repair
« Reply #4 on: November 22, 2012, 01:40:57 pm »
Trace the input circuit. Any sort of bad or loose connection will cause this and often does not affect voltage readings. Had a very similar problem on my Fluke 8840A. Oxidized push-on connectors at the rear of the input jacks in my case.
 


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