Re: PG506 calibrator generator voltage error


Harvey White
 

I just leafed through the schematic, and don't see a capacitor between the two grounds (there are, but they're very small values, like 0.01 uf).  What I'd do is to disconnect the relay board, which should isolate the power supply.  I'd check to see if the resistance you see goes away (I'd expect that the normal behavior is very high resistance between grounds.  There *is* a diode (CR67, I think) between the 5 volt (referred to ground) and isolated ground.  I'd wonder about that.  )

Then I'd check between the two grounds again and see which section has the odd reading.

If you want, I could check one of mine to see if it's behaving itself.

Harvey

On 12/27/2020 3:26 PM, Gif Sim via groups.io wrote:
hi harvey
that's exactly what I think too !!
in fact if I connect an oscilloscope isolated from the mains power supply (battery powered) the pg506 works correctly ....
only that inside the pg506 it's a nice mess !! .....
simon




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