hello eevblogers
please excuse me if that's the wrong section ... I wasn't sure where Shall I open that thread
it's been a year or so since I bought my 3478 .. and the internal Jumper was on the 100/120 ( Can't remember )
so I moved it to the 220 one ... and that's it .. though I've read here somewhere that something like +10VAC on the "higher " end of the voltage rating , is ok for the short term , though bad for the long term of the device/transformer ,
the Humm is much Quite now
Hence today , after seeing Dave's video ( #427 ) . I just opened my meter and did few things :
1) Checked the Battery voltage ( see the pic's below )
2) Changed the Jumper position to 240V AC
3) Measured the LM399's voltage ( Right on the 2 pins ) the voltage reading ( Via my 287 & rel'd ) was 6.885V ( see in the pic's below .. I compared the 287 and the 3478A , NOTE: It's the same rel as with the LM399 testing , Ie . I didn't turn the 287 of or so .. )
Now , Dave mentioned that there should be two transformers right there ( instead of the 2 opto's )
and that exactly What my unit have
and I think I saw Op07 near by the LM399 ( in Dave's unit) ... though mine have some other op amp .. ( any idea ? )
and as per the battery voltage ... does the voltage of mine is Okay ?
BTW .. the last pic shoes the ACmV of the E3610 , Does That measurement correct ? IE ... I don't (yet) have an scope ( I think analog is the recommended here (?) ) ... so Just as A reference ... Does 0.5mVRMS is the correct value ?
thank you in advance