Pages 122 and 123 of the service guide have some information, but I need more details.
primary errors612 Ohms 500 nA source failed 613 Ohms 5 uA source failed615 Ohms 10 uA source failed617 Ohms 100 uA source failed 619 Ohms 1 mA source failed
secondary errors618 DC high voltage attenuator failed 620 AC rms zero failed
Most or all of these errors are caused by Ohmmeter, I suppose you have 34401A model.There is a high probability that the error is caused by Q202, 2N5461 JFET P-Channel Transistor - TO92...obsolete part, but still available on eBay.Q202 it's a critical part, leakage current must be low.If not, there are also:U201-a with Q201 ref current source)Q203-Q211 with CR202 (ohmmeter protection circuit)
I just fixed a meter with similar errors -- the +15 V supply was bad (the 10 uF capacitor and 3.3 V zener diode).
In my message I assumed that the power supplies had been checked, but your remark is very relevant because if for example, cr401 3.3V zener was blowup caused by a defective decoupling capacitor, there would be loss of references +7REF, +5REF and ADC circuit would be affected. The reference +7REF is used for all scales of the ohmmeter.
We have few details of Danielms on the breakdown except the error messages, but I think you have provided a good track.
Thank you, this information is very important!
Tarz, during the check, I noticed a problem in the Q201 transistor.
JohnPi, what is the location of the 10uF capacitor and 3,3V zener diode?
I use the meter to measure the DC current flows through some devices, and it all started during a DC current measurement on a device and that device went short, and after that the meter failed to display correct values.
Hi, there are six 3.3V zener diode: CR304 and CR307 for -15V, CR305 and CR306 for +15V are used in AC voltmeter section, and CR401 and CR402 in Ohmmeter and ADC section. CR401 is used for +15V, and CR402 for -15V. Measure voltage at these points to confirm if this section is good or not. If everything is OK, you may go to Ohmmeter section, but the best thing to do first is to measure all supply on board.
What is the instrument model number that is generating these errors? The error code description should be in the User's Guide and the Service Guide. Unless a troubleshooting and repair procedure is give in the Service Guide, component level repair is not supported. If that is the case, the instrument much be sent to a Keysight Service Center for repair or replacement.
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