Author Topic: BM235 "InEr" Input Error Repair  (Read 471 times)

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Offline Nitrousoxide

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BM235 "InEr" Input Error Repair
« on: January 19, 2020, 03:58:37 am »
Hi all,

I'm sort of at a loss here.

Problem:
I have a BM235 that reports "InEr" (input error) when the range selector switch is on any setting either than current measurement. However, when I switch to the current measurement (uA or mA/A), the meter works fine. This is without any cables connected. As soon as I connect anything to the Amps jack, the alarm sounds. But when I insert a banana jack into the mA/uA socket, it stops beeping.

I'm not too sure what could cause an "input error" to trigger on voltage measurement. The meter has firmware revision C if that is of any help.

To add some extra context: It hasn't been severely dropped or subjected to other extreme conditions.

Attempted solutions:
I have tried:
- Replacing the batteries
- Checking for loose components.
- Cleaning the banana jack receptacles.
- Cleaning the range switch.

None of those has helped.

Any advice would be appreciated, thanks.

Update:
It seems as though If I leave the meter standing I am able to range through all the measurements aside from the low impedance voltage measurement, as soon as I move into that range, the meter reports "InEr" regardless of setting (aside from current ranges).
« Last Edit: January 20, 2020, 12:38:53 am by Nitrousoxide »
 

Online 2N3055

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Re: BM235 "InEr" Input Error Repair
« Reply #1 on: January 19, 2020, 10:20:11 am »
BM235 uses split jacks for plug detection. Check if those are OK, maybe for solder bridges on the board or a piece of wire inside socket. If a mA/uA jack is shorted it would behave just like that..
 

Offline Nitrousoxide

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Re: BM235 "InEr" Input Error Repair
« Reply #2 on: January 19, 2020, 11:44:14 am »
BM235 uses split jacks for plug detection. Check if those are OK, maybe for solder bridges on the board or a piece of wire inside socket. If a mA/uA jack is shorted it would behave just like that..

First thing I checked. I cleaned both the current jacks with isopropyl and some form of abrasion. After inspection, they were free of debris.
I took another meter and did a continuity test. The two sides do not report conductivity (which is expected). Yet, The meter reports an input error.
« Last Edit: January 19, 2020, 11:49:59 am by Nitrousoxide »
 

Offline cs.dk

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Re: BM235 "InEr" Input Error Repair
« Reply #3 on: January 20, 2020, 11:06:57 am »
What batteries are you using? They can't handle some of the lithium AA's; https://www.eevblog.com/forum/testgear/the-bm235-does-not-accept-lithium-batteries/
 

Offline Nitrousoxide

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Re: BM235 "InEr" Input Error Repair
« Reply #4 on: January 20, 2020, 01:29:36 pm »
What batteries are you using? They can't handle some of the lithium AA's; https://www.eevblog.com/forum/testgear/the-bm235-does-not-accept-lithium-batteries/

Thanks for the heads up.

I have tried "Eveready Gold Alkaline" and "Eveready Super Heavy Duty".

One thing to note is that meter had mysteriously come good on its own. However, deciding to play with the range switch causes it to enter its fault condition. After doing a little wiggle of the range switch, it seems to cease beeping and functions!

I guess I did not thoroughly clean the range switch. Or maybe I need to warp the contacts so that more pressure is exerted.

The odd thing about this whole process is that the meter has been sitting on its back, in a sealed box for at least 2 weeks and had not had this issue prior to storage. Always used in smoke free lab, had nothing spilt or dropped on it. Its not even that well worn (used maybe 1-2 a week).
 


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