Question about test signal voltage on DSO 138

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rddube
Posts: 5
Joined: Tue Sep 29, 2015 11:16 am

Question about test signal voltage on DSO 138

Post by rddube »

Hello JYE1,

I have a question about the test signal voltage on my DSO 138 (which is genuine). I get 1.6V on the test ring and not 3.3V as is said on the PCB - is that normal?

I did do the modification to reduce the noise, could that be the reason and is 1.6V ok or there is something I should check? I tested with my voltmeter and each side of R26 and I get 1.6V everywhere including the test ring?

Everything else seems to work fine with my DSO 138 and my signal generator (FG085).

Thank you for your advice!
rddube
Posts: 5
Joined: Tue Sep 29, 2015 11:16 am

Re: Question about test signal voltage on DSO 138

Post by rddube »

Is this forum still active or is the DSO 138 still supported?
jye1
Posts: 1227
Joined: Wed Feb 20, 2013 4:58 pm

Re: Question about test signal voltage on DSO 138

Post by jye1 »

Sorry for late in reply. If you measure with a meter the reading might be an average of the signal which should be about 1.6V for the 3.3V square signal. You can check this out by looking at the waveform on the scope.
viewu
Posts: 13
Joined: Tue Feb 20, 2018 7:51 am

Re: Question about test signal voltage on DSO 138

Post by viewu »

Have you looked at datasheet for U1 pin 17 this seems to be where R6 limits currnt? The datasheet migth tell you what good voltage should be there.
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