Strange voltmeter behavior

[kelLOGg]

I have an old Simpson Model 260 analog volt-ohm meter which when I measure an isolated DC battery voltage with the meter on AC I get a voltage reading. 

For example:
measuring a 9v DC battery with the meter on DC I get 9 VDC. With the meter on AC I get 9.5 VAC

AC voltage sources read ok, e.g.,
measuring 140 AC with the meter on AC I get 140 VAC. With the meter on DC I get 0 as expected.

I don't know when this started happening. Wierd.

[btulloh]

The venerable Simpson 260. Great analog meter. 

Been a long time since I was around one of those, but there's a rectifier in the ac circuit to change the ac voltage to dc. Probably a wheatstone bridge or similar. This would allow dc to be read on the ac setting, but not accurately. This may be normal behavior - probably is. Just don't use the ac range to measure dc voltage. 

[SawyerTed]

I used to teach Electronics at East Carolina University back in the 1980's.  The Simpson was our go to meter.  Digital meters were beginning to be used some.  Digital meters were several hundred dollars then.  

I'm no help because I've forgotten most of my analog meter skills. 

[TimRB]

If there's a coupling capacitor in the AC measurement circuit it may be shorted.

Tim

[Don P]

 

 

ECTC, well how about that