| Electronics > Repair |
| [SOLVED] HP 34401a - Error 612, 613, 615, 617, 618, 619, 621 |
| (1/22) > >> |
| Zucca:
Hi there, Check this last mail email from a cal lab (see full story here https://www.eevblog.com/forum/testgear/34401a-cal-error-707/): --- Quote ---We recently received another 34401A in that has the same issue with the ohms function as your did. Would you be insterested in trying to fix it for us. If you do we can work out some kind of deal with the calibration. Let me know if this is something you'd be interested in? If not, I understand, I will just send your unit back. --- End quote --- After a quick check on this unit, it seems there is a lot to do here, see below the self test results: --- Code: ----> SYST:ERR? <- +612,"Ohms 500 nA source failed" -> SYST:ERR? <- +613,"Ohms 5 uA source failed" -> SYST:ERR? <- +615,"Ohms 10 uA source failed" -> SYST:ERR? <- +617,"Ohms 100 uA source failed" -> SYST:ERR? <- +618,"DC high voltage attenuator failed" -> SYST:ERR? <- +619,"Ohms 1 mA source failed" -> SYST:ERR? <- +621,"AC rms full scale failed" --- End code --- Now I have to start the investigation and post my findings here... Z |
| free_electron:
That looks like the thick film resistor network is shot. check the 9 megaohm resistor in it. most likely it is open. |
| Zucca:
Now I have time to follow this up, so let´s understand what those code means: --- Quote ---612 Ohms 500 nA source failed This test configures to the 10 V dc range with the internal 10 M 100:1 divider U102A connected across the input. The 500 nA ohms current source is connected to produce a nominal 5 V signal. A 20 ms ADC measurement is performed and the result is checked against a limit of 5 V ± 1 V. 613 Ohms 5 uA source failed This test configures to the 10 V dc range with the internal 10 M 100:1 divider U102A connected across the input. The 5 µ A ohms current source is connected. The compliance limit of the current source is measured. A 20 ms ADC measurement is performed and the result is checked against a limit of 7.5 V ± 3 V. 615 Ohms 10 uA source failed This test configures to the 10 V dc range with the internal 10 M 100:1 divider U102A connected across the input. The 10 µ A ohms current source is connected. The compliance limit of the current source is measured. A 20 ms ADC measurement is performed and the result is checked against a limit of 7.5 V ± 3 V. 617 Ohms 100 uA source failed This test configures to the 10 V dc range with the internal 10 M 100:1 divider U102A connected across the input. The 100 µ A ohms current source is connected. The compliance limit of the current source is measured. A 20 ms ADC measurement is performed and the result is checked against a limit of 7.5 V ± 3 V. 618 DC high voltage attenuator failed This test configures to the 1000V dc range. The 500 nA ohms current source is connected to produce a nominal 5 V signal. A 20 ms ADC measurement is performed and the result is checked against a limit of 5 V ± 1 V. 619 Ohms 1 mA source failed This test configures to the 10 V dc range with the internal 10 M 100:1 divider U102A connected across the input. The 1 mA ohms current source is connected. The compliance limit of the current source is measured. A 20 ms ADC measurement is performed and the result is checked against a limit of 7 V ± 3.5 V. 621 AC rms full scale failed This test configures for the 100 mV ac range. The 1 mA ohms current source is switched on to charge the ac input capacitor C301 . This produces a pulse on the output of the rms-to-dc converter which is sampled 100 ms after the current is applied. A 20 ms A/D measurement is performed and checked against a limit of 10 V ± 8 V into the ADC --- End quote --- 618 and 621 are respectively due to 612 and 619, so we can ignore those two. Yes free_electron, the U102A is the first suspected, but in R I have no ohm current source. What if the ohm current source is fried? mmmmm... I will find out... |
| free_electron:
like i said : check the 10 meg divider. pin 1 to pin 12 i believe of that ceramic hybrid. imost likely it is open. i have seen those fail two times. that hybrid is very expensive... like 250$ .. |
| Zucca:
Thanks free_electron to stay with me! I did after I posted the previous one and it was not open. I connected the bad 34401a HI to the I 3A current on a 34461a, and then I connected the two LO between 34401a and 34461a. With 2WR set on the 34401a I got no current flowing in the 34461a. In this set up the 10MR divider doesn't play any role, please tell me if I overlooked something. Thanks a lot! |
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