Hi,
I've bought an 34401A and the self test gives error 611 also the readings are noisy and quite a bit off.
Some readings with shorted leads:
Ohms 2W: starts around 53 Ohm then ramps down to bounce between 41.3 and 41.7 Ohms
mVDC range: bounces between 40.7 and 41.2 mV
1.2VDC range: between 0.00926 and 0.00940 V
12VDC range: -0.0006 V so seem to be ok
Low amp range: between 0.155 and 0.159 A
high amp range: between 0.0412 and 0.0419 A
Error 611 description according to manual:
DC gain x100 failed This test configures for the 100 mV dc range. The
dc amplifier gain is set to x100. The measure customer ( MC ) input is
selected to the internal TSENSE source which produces 0.6 volts. A 20 ms
ADC measurement is performed and checked for a +overload response.
I did some measurements while in mVDC setting and I think that the voltage drop across CR203 is to big.
All measurements are in Volts.
Does anyone have a suggestion how to fix this? Personally I think U201A is the culprit.