FG502 problem?

Chris van Lint


I recently tried to fire up my FG502.  The unit was not working and the green power lamp was not illuminated. I discovered that one of the 741 opamps in the power supply was faulty.  I replaced the 741 and the unit now appears to be working OK.  However although the +20V supply is within specs, the -20V is way out at -30V. The +20V supply is easily adjusted with R625, but I cannot find any adjustment pot for the -20V supply. _The +17V and -17V supplies are also within specs._

- Does this mean that I should not be concerned about the -20V being too high?

- Am I correct in assuming that R672 on pin4 of U664 is out of range?

Any advice would be appreciated


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