Meterman 34XR Fails all AC tests but passes all other tests including DC.

[wagnerpa]

Any suggestions on what may have failed?  Have taken in for calibration and meter fails all AC tests (voltage, amps); but the DC, resistance, frequency, capacitance all pass the calibration tests.

AC voltage gives an unpredictable reading, always higher than should be - sometimes double.

Unable to find circuit drawing - anyone have one available?

[floobydust]

Wavetek/Meterman/Amprobe 34XR

I usually find the RMS-to-DC converter IC is dead, like an AD737 or similar. You can look at the PCB for the IC used.

Amprobe Service and Support is really good giving service manuals if you email them a request.

[wagnerpa]

Thanks.  The 34XR has an ES636 (SOP packaging) RMS to DC converter.  Will try to replace with an AD636 (SBCDIP)!
Haven't found availability of ES636 or an SOP packaging equivalent.

[floobydust]

If you replace the RMS-DC converter, it could have one or two associated trimpots to adjust span and offset.

[soesante]

Hi @wagnerpa,
did you manage to fix your meter ?
I have almost similar issue with my BM869S.
When measuring AC voltage from main outlet, it show OL. but the frequency measuring correctly 50 Hz
(I attached the Pic)

I think the same RMS - DC  problem, anyone have any idea ?