Fluke 5700a repair

[veedub565]

After posting on a few different and random threads I thought it might be best to create my own Fluke 5700a repair thread. I've already had some hints and tips from TiN. I've already made a few mistakes and done some things wrong, but no harm seems to have been done.

So, I have acquired a Fluke 5700a physically and cosmetically in good shape, but with some faults

Date of last cal 2013

I guard rear terminal post snapped off

ETIME = 7422640 (14yrs)

FATALITY =
1/20/92    10:21:03   Fault    1822   5220  No Longer Connected
7/13/28    13:45:13   Fault    1824   5205 No Longer Connected
7/18/28    13:30:00   Fault    1824   5205 No Longer Connected
3/18/95    08:54:07   Fault    1602   Unexpected NSA From Inguard
3/18/95    08:54:17   Fault    4012   Sequencer Timed Out Waiting For Inguard
3/18/95    08:54:27   Fault    4012   Sequencer Timed Out Waiting For Inguard
3/18/95    08:54:37   Fault    4012   Sequencer Timed Out Waiting For Inguard
3/18/95    08:54:47   Fault    4012   Sequencer Timed Out Waiting For Inguard
3/18/95    08:54:57   Fault    4012   Sequencer Timed Out Waiting For Inguard
3/18/95    08:55:07   Fault    4012   Sequencer Timed Out Waiting For Inguard
3/18/95    08:55:17   Fault    4012   Sequencer Timed Out Waiting For Inguard
3/18/95    08:55:27   Fault    4012   Sequencer Timed Out Waiting For Inguard
12/20/00    12:36:08   Fault    1602   Unexpected NSA From Inguard
12/20/00    12:36:18   Fault    4012   Sequencer Timed Out Waiting For Inguard
3/18/13    10:38:27   Fault    232   5725 Illegal/Unexecutable Command
3/18/13    10:39:26   Fault    232   5725 Illegal/Unexecutable Command

I ran the self diag and it came up with a few errors (there was an error with the A12 card, but this was resolved by fitting a spare card.
Yes I know the cal values will be incorrect now. I have access to a cal lab and I may be able to arrange to have this unit re-certified IF I get it repaired.
Yes I know swapping cards willy nilly without first recapping and smoke testing the PSU is NOT they way to do it. That's a good way to blow up a good card. Too late, it is done, and I appear to have been quite lucky.

A8: Relay Fault (3819)
A15: DC HV Amp Offset Fault (3107)
A5: ODB Output Attenuation Fault (3914)
A5: 10DB Output Attenuation Fault (3915)
A5: 20DB Output Attenuation Fault (3916)
A5: 30DB Output Attenuation Fault (3917)
A5: 40DB Output Attenuation Fault (3918)



to check the base hardware I ran self diag without A5/A6 and A14/A15/A16 cards and only reported fault was
A8: Relay Fault (3819)

[veedub565]

First order of business now is to replace ALL electrolytics as they will be at the end of their useful life. Also to replace the carbon composite resistors, especially the 1W ones which are to be replaced with 3W ceramic. I'm also going to replace the fans with some Sunon ones.

How do I know which is the correct lead pitch for the capacitors ? some appear to be 5mm, some 10mm, some in between. And there are 4 or 5 different options when ordering new ones

Also a good idea to remove all the cards and give the chassis a good clean and remove all the dust inside.

I would also like to be able to get the cal report from it, but I'm still having some difficulty with this.

-> *IDN?
<- FLUKE,5700A,5185014,HA*

-> CAL_RPT?
 ! VI_ERROR_TMO: A timeout occurred
Visa ErrorCode: 0xBFFF0015 (-1073807339)

<- FLUKE,5700A,5185014,HA*
-> cal_rpt? check
<- "«x0A»«x0A»«x0A»«x0A»«x20»«x20»«x20»«x20»------------------------------------------------------------------------«x0A»«x20»«x20»«x20»«x20»JOHN«x20»FLUKE«x20»MFG.«x20»CO.,«x20»INC.«x20»«x20»«x20»«x20»«x20»S/N«x20»5185014«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»5700A«x20»CALIBRATION«x20»CHECK«x0A»«x20»«x20»«x20»«x20»PRINTED«x20»ON«x20»29.05.08«x20»AT«x20»15:46:54«x20»5700A«x20»«x20»S/N«x20»5185014«x0A»«x20»«x20»«x20»«x20»--------------------«x0A»«x20»«x20»«x20»«x20»------------------------------------------------------------------------«x0A»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»MODULES«x20»PRESENT«x0A»«x20»«x20»«x20»«x20»------------------------------------------------------------------------«x0A»«x20»«x20»«x20»«x20»Software«x20»Revision«x20»HA*«x0A»«x20»«x20»«x20»«x20»Switching«x20»Matrix«x0A»«x20»«x20»«x20»«x20»DC«x20»Volt«x20»Module«x20»«x20»«x0A»«x20»«x20»«x20»«x20»AC«x20»Volt«x20»Module«x20»«x20»«x0A»«x20»«x20»«x20»«x20»220V«x20»Module«x20»«x20»«x20»«x20»«x20»«x0A»«x20»«x20»«x20»«x20»1100V/2A«x20»Module«x20»«x0A»«x20»«x20»«x20»«x20»Current«x20»Module«x20»«x20»«x0A»«x20»«x20»«x20»«x20»Ohms«x20»Module«x20»«x20»«x20»«x20»«x20»«x0A»«x20»«x20»«x20»«x20»Wideband«x20»Module«x20»«x0A»«x20»«x20»«x20»«x20»Hires«x20»Osc«x20»Module«x0A»«x20»«x20»«x20»«x20»Rear«x20»Panel«x20»«x20»«x20»«x20»«x20»«x20»«x0A»«x20»«x20»«x20»«x20»------------------------------------------------------------------------«x0A»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»«x20»ARTIFACT«x20»CALIBRATION«x20»DATES«x20»AND«x20»TEMPERATURES«x0A»«x20»«x20»«x20»«x20»-------------------------------------------


I'm not sure what I'm doing wrong here. I'm not familiar with Python unfortunatly, and I'm not sure I'm sending the correct commands and the response seems to be a bit rubbish 

[Kleinstein]

For the capacitors there may be an info in the parts list if provided in the service manual.
Alternatively measure the real thing.  If it is off a little (e.g. 6 mm VS 1/4 inch) this can be sill acceptable. Chances are there are not that many different types actually used. So if you don't find tham all in the measurement run - same values are likly same spacing / though not sure).

With the carbon composite resistors one may have to be carefull in the high voltage and higher frequency parts. Wire wounds usually have more inductance and may not have the same withstand voltage. Higher resistance values (e.g. > 100 K) can be tricky as wire wound. Sometimes the resistor case  / rating in choosen because of the peak voltage and not just power.

[veedub565]

For the capacitors there may be an info in the parts list if provided in the service manual.
Alternatively measure the real thing.  If it is off a little (e.g. 6 mm VS 1/4 inch) this can be sill acceptable. Chances are there are not that many different types actually used. So if you don't find tham all in the measurement run - same values are likly same spacing / though not sure).

With the carbon composite resistors one may have to be carefull in the high voltage and higher frequency parts. Wire wounds usually have more inductance and may not have the same withstand voltage. Higher resistance values (e.g. > 100 K) can be tricky as wire wound. Sometimes the resistor case  / rating in choosen because of the peak voltage and not just power.

I had a look at the parts list in the manual, it provides all the values, tolerances etc, and even part numbers (although finding data on 30yr old part numbers is hard to say the least) I have started physically measuring the pitch, mostly the bigger ones are 10mm and the smaller ones are 5mm but there are a few in between. I guess it doesn't really matter too much, even Fluke have stretched the legs out on some. I just want to try and make it neat and tidy. It's more important for the bigger ones that the pitch is correct.

I'm going to use Carbon Film to replace the old Carbon composite resistors as this appears to be what Fluke have used in the series II version. For the higher power values (3W) Fluke list ceramic, but the pictures I've seen show a thick film resistor being used, so I'll go for them (https://www.digikey.com.au/product-detail/en/tt-electronics-irc/GS-3-100-2203-F-LF/989-1203-1-ND/2408023)

[veedub565]

Well picking the right replacement caps is proving to be a right PITA. The part numbers themselves contain no information at all relating to the lead pitch. So I've been physically measuring the pitch and there appears to be 4 different flavours, 2.5mm, 5mm, 7.5mm, and 10mm. Here's an example of a problem I just discovered

There are 11 22uF 35v electrolytics in the whole unit, I measured one and it had a 5mm pitch. Great I'll order 11 of those.. . Not so fast! some of them are a 5mm pitch and some of them are a 2.5mm pitch, I wouldn't be surprised to also see one with a 7.5mm pitch.

So I've either got to physically measure, and log the pitch of every single electrolytic in the entire unit. So that I know for a given value how many of each pitch I need to order. Either that or order 11 of each flavour in order to cover all eventualities.

[bdunham7]

So I've either got to physically measure, and log the pitch of every single electrolytic in the entire unit.

I'll be looking forward to reading more!

As for ordering parts, I'm going through a less-desirable 5101B right now and it is the first time I'm doing a complete overhaul vs repair, so I'm doing the same thing and have the same issue.  What I'm doing is pulling each individual board and making a list/project file for it so that I can order the parts in groups.  Mouser lets you save 'projects' like this so I can just order a parts group by board number.  And yes, you have to measure all the dimensions of each capacitor and it is a huge PITA.  Its like separate groups designed each board and they weren't on speaking terms.  Mine has a plague of tantalum decoupling caps and they have used at least 10 different types throughout the unit. 

[veedub565]

Ah I'm glad it's not just me then. Just after I posted I came to a similar conclusion, that I'm going to have to break it down and make a list of parts for each separate board. Treat each board as a mini project all it's own. Haven't even started on the Tants yet !

I always knew this was going to be a long term project, still could be worse at least this one is complete and in decent shape overall.

5101B looks an interesting bit of kit worth saving

[TiN]

Response is correct, but crappy VISA you used shows ASCII data as hex values. I'd suggest using Raspberry Pi with one of the images (like one recently posted by e61_phil in metrology section) to capture reports over GPIB.

Don't forget to replace carbon composition resistors, especially on 14,15,16,17,18 boards .

I'd also ditch boards 5 and 6 out of calibrators until you get everything else working. A8 error means most likely unhappy tests with some stuck relay somewhere (not necessarily on A8 )

[veedub565]

Thanks TiN, I've got a Raspberry Pi to try this with, although I'm no programmer.

ALL carbon composite resistors are going to be replaced. Actually very little evidence of burning on the A18 board, even with 14yrs operation. I tested the 220k 1W CC resistors and they are all approx 220k except for one which is more like 250k. Maybe a new board was fitted at some point. Anyway they are all going to be replaced and the 1W ones upgraded with 3W thick film 100ppm

Yes tracking down stuck relay is going to take some time. I already removed A5/6 and still get the relay error. I'm going to work through this sequence (attached) and see where I get the error

[veedub565]

Its like separate groups designed each board and they weren't on speaking terms.

I'm beginning to wonder if each board had separate groups working on it who also didn't talk to one another.

A17 board -
C8,C13 = Tantalum 22uF, 25V, 20%, T356G226M025AS
C67-70 = Tantalum 22uF, 25V, 20%, T361B226M025AS

So identical value, voltage, tolerance tantalum caps. Except 2 of them are 356 series and 4 of them are 361 series.... on the same friggin board ? 

Pitch is the same, physical size is the same.... you have to wonder if there is some specific reason why the 356 series was chosen for one part of the circuit. And the 361 series was chosen for another part of the circuit. And if that's the case,  you have to wonder if it's wise to blanket change all the tantalum capacitors, unless you replace like for like with the exact same series and not just the same value.

[bdunham7]

You can try to look at the circuit to see how the tantalum cap is used, but AFAIK they are all non-critical decoupling types of applications.  By non-critical, I don't mean you can use just anything, but I think any similar tantalum should be fine.  They use a lot of the less common values--instead of 33,47,68, you see 39, 51, etc.  I'm just using a close value--and I think up or down is OK, so for a 39, I have no problem with a 33 or a  47--and as high a voltage as I can get, either 35 or 50 volts depending on the size.  I'm still going to need at least 7 different part numbers just for the tantalums.  Then there are the weird value polypropylene film caps...

These are sophisticated instruments, but that doesn't mean every design choice was a stroke of genius.  The power supplies alone should be prove that--the 5100 series PSU boards are prone to going up in flames.  Here's one design and component that I think takes the cake---it is a simple switch that takes a resistor in and out of an oscillator circuit on the AC oscillator board.  They could have used anything, but this is what they chose:

[veedub565]

They do just look like decoupling caps. I found where they are in the circuit, and interestingly C8,C13 have TANT marked on the schematic where C67- 70 don't. Although it says TA for both on the part list. I wonder if some are tantalum polymer and some are straight tantalum.

I attached a picture from the schematic showing both, and an extract from the part list also showing both.

[veedub565]

First parts order placed £164 worth of electrolytic capacitors, metal film and precision wire wound resistors, and a couple of Sunon fans. Not a cheap project ! and still the original faults to fix after this.

Still making my mind up about the tants, if any were going to fail they would have done by now. And they don't dry up and age like electrolytics.

[TiN]

Still making my mind up about the tants, if any were going to fail they would have done by now. And they don't dry up and age like electrolytics.

They probably will be just fine, but I wouldn't be able to sleep at night or go to work at same time knowing that at home there is $20k calibrator running 24/7 and if $3 tantalum cap starts fire, nobody will be there to save it. You going thru all trouble to repair unit, why stop half-way? 

Btw, you asked about extenders for boards.

Here is the Gerber file for it. Provided AS IS.

Layers stackup:

TOP - L1 top external layer
INT1 = L2 1st inner layer
INT2 = L3 2nd inner layer
BOTTOM = L4 bottom external layer

[veedub565]

Yes that is a good point, going to all the trouble to refurbish it why stop half way. I'm sure I read something about replacing a few zener diodes in one of your blogs, I can't find where I read it now though.

Many thanks for the gerber file, I have made an order for these with JLC PCB. I think minimum order was 5 so I have some leftover if anybody else comes across this and needs one. Trying to fault find without the extender card would be very difficult.

[TiN]

Funny enough, most of boards I fixed without use of extenders. I got them only when I was troubleshooting wideband assembly. Perhaps having no case helped back then 

[veedub565]

Yes I guess it must be possible to do without the extender cards, they will make life easier though. I think because the cards are close together, even without the case it makes it difficult to get a probe on the measurement points.

I will try and get some pictures of this project soon.

[veedub565]

So a small update on the 5700a repair.

All boards removed, I've cleaned out the chassis, wow it was full of so much dust and crap! looks much better now it's clean. I took the opportunity to check the A3 motherboard relays, all check out ok.

New Sunon maglev fans fitted,  these run much quieter than the originals.

So far all capacitors and carbon comp resistors replaced on A21,A20,A19,A18. ALL of the carbon comp resistors had gone up in value, most of them had gone outside of tolerance. So well worth replacing them. It was interesting to note that the new parts were both higher in spec than the originals, and in many cases smaller size. Technology marches on!

The GPIB connector works, but has a bent pin so must be replaced. I'm having some difficulty sourcing the correct replacement part though. I've salvaged a couple from old equipment but the pins are too short.

The "I Guard" terminal on the rear is snapped off. I was going to replace this, but when I removed the A21 board I found that the rear terminals, although fitted, are not actually connected up to anything. So a bit strange, but at least I don't need to bother repairing this now.


It was powered up with A3+A4 + A19+A20 + A1+A2 Front panel + A21 +A18, I got the expected hang on error “Guard crossing”. Next task is to check the voltage rails. I'm expecting things to be a bit tighter in tolerance than before.

[veedub565]

Two resistors, both the same value, both the same power rating, big difference in size

[picburner]

I was going to replace this, but when I removed the A21 board I found that the rear terminals, although fitted, are not actually connected up to anything.

Even in my F5700A the rear terminals are connected to nothing, it probably depends on the various options of the instrument.

[veedub565]

I was going to replace this, but when I removed the A21 board I found that the rear terminals, although fitted, are not actually connected up to anything.

Even in my F5700A the rear terminals are connected to nothing, it probably depends on the various options of the instrument.

That's useful to know, so looks like all of them came with the rear terminals, but only wired up as an option.

[veedub565]

I need to sort out some image hosting, keep hitting the maximum upload size here.

[pcwrangler]

Two resistors, both the same value, both the same power rating, big difference in size

Always amazed at the progress of some components. Depending on the project I sometimes take the opportunity to increase power rating for reliability/longevity since space permits. Nice repair/restoration btw. Watching for pics.

[YetAnotherTechie]

Two resistors, both the same value, both the same power rating, big difference in size

Yeah, i've seen those, but just because progress has made 1/8W resistors able to withstand higher temperatures, and be relabeled as 1/4W doesn't make it right. Imagine the case were the old resistor was dissipating 0.15W, maybe its surface temperature would be 50ºC, on the new one, i wouldn't be surprised if the surface temperature was >100ºC

[veedub565]

Two resistors, both the same value, both the same power rating, big difference in size

Yeah, i've seen those, but just because progress has made 1/8W resistors able to withstand higher temperatures, and be relabeled as 1/4W doesn't make it right. Imagine the case were the old resistor was dissipating 0.15W, maybe its surface temperature would be 50ºC, on the new one, i wouldn't be surprised if the surface temperature was >100ºC

Well I did wonder I must admit, it doesn't look right. I ordered replacement parts as per OEM spec though, and that's what turned up. I ordered Metal film in this case to replace Carbon Composite.

It's a bit difficult, if the parts list says 1/4W and you order 1/4W and then it turns up a fraction the size of the original part. It's a bit difficult to try to second guess everything.