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DT9205A multimeter fault in voltages measurements

Technician Tonny

Aug 31, 2015
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Hello Technicians
I'm Tonny, I need your help plz
I have 3 digital multimeter DT9205A with the same problems
They can't display measurements of DC and AC
Thanks
 

shrtrnd

Jan 15, 2010
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Don't know your exact problem, like, are you at least seeing zeros in the display, or a dead display.
Most multimeters have two fuses. One for the voltage meansurements, and one for the amp readings.
Did you check the fuses?
 

Old Steve

Jul 23, 2015
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Don't know your exact problem, like, are you at least seeing zeros in the display, or a dead display.
Most multimeters have two fuses. One for the voltage meansurements, and one for the amp readings.
Did you check the fuses?

That model only has a fuse in the current measurement circuitry, according to the manual. Just the lower current ranges, too, not the 20A range.
The manual:-
https://arduino-info.wikispaces.com/dt9205a-multimeter-manual
 

shrtrnd

Jan 15, 2010
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Well, the only other DMM I ever saw that had a current-side only fuse, used a big resistor designed to fuse open-circuit at over-voltage of the meter.
Thanks for the info Old Steve.
My advice then to Technician Tonny, is to open the meter housng, and look for bruned-up components.
 

Old Steve

Jul 23, 2015
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yes Steve
This problem occurred when i was measuring the B+ of the CRT tv circuit
I didn't mean to sound rude, but since you didn't mention if it was new or previously used, I thought I'd better ask about the battery.
The B+ voltage itself on a CRT TV isn't usually a particularly high voltage and the DMM should have been able to handle it, I would think. Most likely, it got a zap of HV from the flyback transformer. In that case, it is probably dead.
If I were you, I wouldn't waste further time trying to fix it. It's a relatively cheap meter. I'd just replace it, personally.
Edit: I just re-checked the manual, and on the DCV ranges it should be able to handle 1000VDC. Even if you had it set on the wrong range, below 200VDC, it should have just displayed an over-range symbol, so HV almost certainly killed it. You could look for burned components as suggested by shrtrnd, but aside from that I'd recommend that you simply replace it as I suggested earlier. Sorry I can't be of further help.
 
Last edited:

Technician Tonny

Aug 31, 2015
34
Joined
Aug 31, 2015
Messages
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Well, the only other DMM I ever saw that had a current-side only fuse, used a big resistor designed to fuse open-circuit at over-voltage of the meter.
Thanks for the info Old Steve.
My advice then to Technician Tonny, is to open the meter housng, and look for bruned-up components.

shrtrnd I see only 1 fuse and 3 ICS
I have changed the lm358, lm324 and the near by components
But still the same problem
 

Technician Tonny

Aug 31, 2015
34
Joined
Aug 31, 2015
Messages
34
I didn't mean to sound rude, but since you didn't mention if it was new or previously used, I thought I'd better ask about the battery.
The B+ voltage itself on a CRT TV isn't usually a particularly high voltage and the DMM should have been able to handle it, I would think. Most likely, it got a zap of HV from the flyback transformer. In that case, it is probably dead.
If I were you, I wouldn't waste further time trying to fix it. It's a relatively cheap meter. I'd just replace it, personally.
Edit: I just re-checked the manual, and on the DCV ranges it should be able to handle 1000VDC. Even if you had it set on the wrong range, below 200VDC, it should have just displayed an over-range symbol, so HV almost certainly killed it. You could look for burned components as suggested by shrtrnd, but aside from that I'd recommend that you simply replace it as I suggested earlier. Sorry I can't be of further help.

Ohk thanks Steve
nice day
 
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