Electronics > Repair

HP / Agilent 3312A 16V on power led

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TNTdesigner:
I When i turn my 3312A on the 17V and -17V are fine, but the generator did't start, after some probing around I fount I had 16.2V on the power on led. I suspect the 1820-0203 linear amplifier but I can't find any datasheet for it. Does anyone have a goed datasheet for this part or a newer replacement part number for this part ?

berik:
The 1820-0203 should be very similar (if not identical to) a LM301A.
Why did you suspect the 1820-0203 op-amp if I may ask?

berik:
According to Bench Briefs 4th Quarter 1987,
the 1820-0203 can be replaced by a UA741HC datasheet

wn1fju:
Doesn't make much sense to me.  What do you mean, 16.2V on the power LED?  That LED goes from ground, through the LED, through a 1K current limiting resistor and then to the -17V1 rail (via another 10 ohm resistor).  When operating, one side of the LED should be 0V and the other side should be about -2V.

When you said that the 17V and -17V voltages are correct, be aware that according to the schematic, there are multiple variants.  For instance, there is a -17V
line, a line marked -17V1 and a line marked -17V2.  The V1 and V2 lines come off of the main -17V through inductors.  So you need to verify that the inductors are good and you have all the voltages marked on the schematics.  Same thing for the +17 and its multiple copies.  Only after this should you start to suspect faulty opamps.

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