Re: PG506 calibrator generator voltage error


Eric
 

Hey Simon,
Measured with a Keithly DMM6500 standard output jack to the aluminum frame. In a frame and out of a frame.
In frame, resistance that rapidly went up to overflow. I believe a cap was charging.
Out of a frame, Same behavior.

Once charged infinite resistance.

Eric

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Gif Sim via groups.io
Sent: Sunday, December 27, 2020 2:10 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] PG506 calibrator generator voltage error

hi eric
yess..I did as you wrote ... the pg506a used it long ago and it was perfectly calibrated and working (I calibrated some 2465b and 2467b)

the strange thing is that if I connect an oscilloscope with 1Mohm input, battery powered, therefore not connected to the mains electricity, to the amplitude standard output, the levels are correct ... the variable out potentiometer works and the display indicates the value set with the pot ....

but if I connect an oscilloscope (such as a tds 784d) with 1Mohm input, powered by the mains electricity, the output voltage is wrong (for example if I set 2 v to the output or about 2.4 v) ... .the variable out potentiometer has no effect on the output voltage and the display indicates a fixed value

my calibrator is the PG506A and one of the latest revisions of the boards there are no relays you find in the first PG506

I checked q325-q365-q326-q320-q280-q290-q245-q255-q270-q190 by removing them from board A1 and trying them with a component test they are all okk...

i checked all diodes and zener on board A1 and they are all okk now i am trying and replacing some electrolytic and tantalum capacitors on board A1 (but so far i haven't found any wrong ones)

Eric can you do me a favor? ... with the PG506 off, set to standard ampl and the selector on 2volt, if you connect the cables of a multimeter between the mass of the standard out female bnc and the aluminum frame of the PG506, what a resistance read the multimeter?

thanks eric and thanks to all those who can give any suggestion to understand the problem!
simon

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