Fluke 5700A Repair

[CrazyTiger]

Hi,
I got my hands on a Fluke 5700A. The calibrator has a strange behavior where the output trips when I turn on EXT sense on Voltage DC and AC and measurements are bad at 4 wire ohms as well, so basically anything to do with Ext Sense is bad.

However the instruments works perfect if Ext sense is off. The unit self-test, diagnostics is good. I am yet to open up the instrument, been reading the service manuals preparing for the weekend. Tripping occurs when the the calibrator output is drawing too much current. So likely I am looking for shorted components, but My first two suspected modules will be the motherboard and the switch matrix module. Any other module I should be focusing?

[Swake]

You have to watch the video from Marco Reps about the repair of his 5700A.
 

He also makes a reference to the xDevs website with interesting information on 5700A calibrator review and service https://xdevs.com/fix/f5700a/

It is quite an adventure you started there, good luck !

[CrazyTiger]

Update:

Could not sleep yesterday, so woke up middle of the night and tried re-seating all the boards and  gently tapping (more like knocking) the relays. Unit now working with sense ON too. But I have noticed while running diagnostic few times, 15S supply seems to fail every now and then, so does Osc A13. However the I don't see obvious changes in DC or AC voltage measurement on my 3458A, but I am yet to run any long term measurement.

 15V on the A17 module seems good. However ESR is bad on almost all of the capacitors on A17, worst so far is ESR of 100 ohms on those low profile 22uf 35V Cap, both in and off circuit.



Based on the circuit, it makes sense this cap might be causing the error on A13.

Ordered tonnes of nichicons capacitor, will be recapping all modules, slowly

[Louis_C]

I have a Fluke 5700A that self destructed a couple months ago. The unit was sitting idle in the morning after running the self check when we came into the lab. One of the tech's went to use the 5700A and it literally went up in a small cloud of smoke. Long story short, the A18 took the brunt with ALL the capacitors blowing out and taking several cards with it. I managed to get the 5700 up and running with some errors on AC. I went to do the ext cal with a Fluke 732A and input my true value voltage of 10.0001308 VDC. Now, I have a laundry list of errors here (please see attached). I am over my head and don't know what to do now. ANY help, info or prayers would be greatly appreciated. Thank you.

Errors in order from internal cal check…

With A12 REMOVED

A11 13v reference range fault 2817
A11 -11v DC range fault 2811
A11 -22 DC range fault 2813
A11 6.5v buffer reference fault 2814
A11 6.5v reference fault 2815
A11 13v buffered reference fault 2816
A11 13v reference fault 2817

With A12 INSTALLED

DAC monitoring fault 2809
A11 13v reference range fault 2817
A11 -11v DC range fault 2811
A11 -22 DC range fault 2813
A11 6.5v buffer reference fault 2814
A11 6.5v reference fault 2815
A11 13v buffered reference fault 2816
A11 13v reference fault 2817
A11 ADC amp output offset fault 2807
A8 zero amp high gain fault 3809
A8 22mv divider fault 3815
A8 relay fault 3819
A12/A13 DAC 15th bit fault 3416
A12 DC sensor buffer fault 3417
A12 AC cal sensor 2v range 3421
A11 6.5v buffered reference fault 2814
A9 diff amp gain fault 3309
A9/A10 10 ohm check fault 3331
A9/A10 1 ohm check fault 3333
A9/A10 1.9 ohm check fault 3334
A9/A10 ohms short check fault 3335
A9/A10 10 ohm cal diag fault 3315
A9/A10 19 ohm cal diag fault 3316
A16 pwr amp DC cal network gain fault 3528
A16 pwr amp 220v range attenuator fault 3529
A167/A14 220v AC range output fault 3508
A15 DC HV amp offset fault 3107
A15 DC HV amp gain fault 3108
A15/A15 HV AV 1khz output fault (LO) 3128
A15/A15 HV AV 1khz output fault (MID) 3129
A14/A15 HV AC 100hz output fault (LO) 3131
A14/A15 HV AC 100hz output fault (MID ) 3132
A14/A15 HV AC 100hz output fault (MID ) 3137
A14/A15/A16 2.2A AC range abs. fault 3140

[alm]

I have a Fluke 5700A that self destructed a couple months ago.

I would recommend opening another topic and leave a link here so we don't have two separate repairs getting confused. Also, it would help if you could describe what you did between the 5700A releasing magic smoke and now. If all the caps blew up on A18, then I would be very worried about anything else that's hanging off the same rail, which depending on the rail might be a lot. I would also be suspicious of any carbon composition resistor in that instrument. Did you read what's been written before on this forum, especially by TiN, and on his site xdevs.com?
https://xdevs.com/fix/f5700a/
https://xdevs.com/fix/hulk/
https://xdevs.com/fix/hulk2
https://xdevs.com/fix/hulk3/

[CrazyTiger]

Update:

I have recapped all the electrolytes in the calibrator.
Now awaiting for the tantalums and the carbon composition resistors, most of the carbon resistors are way out of  tolerance as expected. Element14/Farnel is taking their own sweet time to deliver   
Anyway I still have an intermittent problem with AC output, Ac output trips, like once in a week. Sometimes it fails diagnose on A14/A16 (220V AC Ranges), A14 checked out good. But on A16 module,I found one transistor shorted.



Its weird that even with the transistor shorted, the output is good at high voltages, with and without sense ON. I still need to read up what this section do.
Any suggestion for the transistor, MPSh10 is long obsolete.

Thanks