PCSGU250: Different values on channel 1 & 2

Instruments PC Oscilloscopes and Recorders
1

Hi,

I have a PCSGU250 - and the values shown on the 2 channels are different.
If I connect both probes to the same source - the DC-MEAN, MAX, MIN are different.
I switched the probes (connections) to identify if the mismatch is coming from the probes.

  • same result. The channels show the same values - independent which probe is connected
    (so the probes can’t be the failure cause)

I did several calibrations - no improvement.
Channel 1 is very close to my DMM. So I assume channel 2 is not correct

Is there any adjustment possiblity (maybe in an inifile - or so ?)

Thanks in advance
pwo

P.S: here example values
Channel 1 / Channel 2
DCMean 4,97V / 4,88V
Max 5,06 / 4,97V
Min 4,97 / 4,88
Pk-to-pk: 0,09 / 0,09

P.s.S:
Software is running on a XP home / SW-Version 1.12 / Firmware 1.01

2

[quote]I did several calibrations - no improvement.[/quote]The calibration affects only the DC offset - not gain.

[quote]Is there any adjustment possiblity (maybe in an inifile - or so ?)[/quote]The only way is to use the trimpots (RV2 for CH1 and RV3 for CH2) to adjust the gain.
The error you noticed is not very big - less than 2%.
It is well within the specs DC to 12 MHz ±3dB.
Typical DC accuracy is ±3%.

3

Hi,

thanks for the information.
Where can I find the RV2 and RV3 trimpots ?
Must I open the instrument ?

Thanks in advance

4

[quote]Where can I find the RV2 and RV3 trimpots ?[/quote]They are on the circuit board.

[quote]Must I open the instrument ?[/quote]Yes.

Please note that all warranty is void when the unit is opened.

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