Electronics > Repair

3458A Repair

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Shiv:
Hi all.
I´m trying to repair 2 3458A (at least make one from both)

N1: We was using this until failed
-114 Multislope rundown convergence: suspected A3 board with no replacement.
-209: Harware Failure: Timeout - Unable to read A/D: I don´t know from where I should start searching.


N2: Was a mule, multiples failures, stored for more than 5 years:
- It has no fan (replaced)
- It has no reference (repaced)
- RAM Test 1 Low (fixed with new dallas nvRAM, only 1230´s, I have no programmer yet)
- Bad A3 board (don´t show any measurement)  -> replaced by the other A3 and starts measuring, but fails after a while

Actually has:
- HARDWARE FAILURE FLATNESS DAC CONVERGENCE 198 -> Suspected failing A2U404  (+: 6.86V -:6.52V)
-101: CALIBRATION ERROR  (AutoCal fails at first step)

PostScript: Changing A2 from first to second removes errors and start working, passes self test and autocal, but then, time passes:

209: Harware Failure: Timeout - Unable to read A/D:229
114: SYSTEM ERROR: Multislope Rundown convergence
101:CALIBRATION ERROR

When CAL 0 is executed, it shows:
205: HARDWARE FAILURE CAL VALUE OUT OF RANGE:13


Any clue?

coromonadalix:
you may get some hints on xdev's website, schematics too in some instances, may not be complete

you do know they are delicate equipments to work with,  please do take antistatic precautions

a first step would be to check all psu sections / voltages and noise on the voltages if any, recap if needed.

Kleinstein:
The multiple failures with unit 2 could very well be a supply problem. Otherwise  the obvious way to test would be to use the A3 board from unit 2 in unit 1. The errors 114 and to a good chance also 209 are from the ADC board. The first fix / check there would be the comunication problem - best case it would be a loose fiber connector.

coromonadalix:
Even saw a post of a fiber optic cable not inserted correctly, creating some error codes ... 

bsdphk:
The 3458A is quite sensitive to power-supply noise, so start with checking that all the psu rails are clean and in spec.

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