Author Topic: Old Fluke Multimeters  (Read 229981 times)

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Offline Q2A

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Re: Old Fluke Multimeters
« Reply #525 on: September 14, 2018, 05:13:06 pm »
I just got a supposedly NIB 8060A off of eBay, it has not arrived yet. I found this thread fascinating when I stumbled across it a few months ago so I started occasionally looking for an 8060A since I do audio repair and design work and I like older test equipment. The seller says there is a dim character in the display; I have not had time to read the entire thread yet so I'm not sure if that is repairable. First thing will be to check for leaking e-lytic caps - probably just replace them all. So yeah, I'm a bit excited about it...!

Tim
 

Offline retiredcaps

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Re: Old Fluke Multimeters
« Reply #526 on: September 14, 2018, 05:27:45 pm »
I just got a supposedly NIB 8060A off of eBay, it has not arrived yet.
This one?

https://www.ebay.com/itm/292716321279
 

Offline GregDunn

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Re: Old Fluke Multimeters
« Reply #527 on: September 21, 2018, 03:48:08 am »
Well, Flukers (is that too crude?   >:D ) it looks like I have an 8800A/AF on the way.  Guaranteed working, pictures supplied of the unit allegedly powered up and working in multiple modes.  Fingers crossed, it's supposed to arrive tomorrow.

Now, business: this, and my 8600A, are likely in ticking time bomb mode as far as electrolytic caps are concerned.  I've read almost all of this thread, and it seems maybe the aluminum poly caps are the best replacements?  How about for replacing the tantalums?  I'm putting together a BOM to get my meters updated so (without starting any arguments) what's the consensus?
 

Offline helius

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Re: Old Fluke Multimeters
« Reply #528 on: September 21, 2018, 04:46:41 am »
Aluminum polymer caps have lower ESR than wet caps, but in some cases leakage is more important, and they are worse with respect to leakage.
 

Offline GregDunn

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Re: Old Fluke Multimeters
« Reply #529 on: September 21, 2018, 05:15:37 am »
So, perhaps one type would be better suited to the meter's measurement circuitry and the other type to the power supply filtering?  Or is it that simple?
 

Offline vindoline

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Re: Old Fluke Multimeters
« Reply #530 on: September 21, 2018, 12:07:12 pm »
So, perhaps one type would be better suited to the meter's measurement circuitry and the other type to the power supply filtering?  Or is it that simple?

Congratulations on the new (old!) meter. First off, I don't have an 8600 or 8800, so I can't comment on those specific circuits. However I have about 6-8 Fluke 8060A handhelds that I've refurbished and love. In the 8060A, the failure of the aluminum electrolytic caps is so well documented that I agree with preemptively replacing them all. That said, I don't generally recommend replacing working parts just because they might fail in the future.

When replacing parts, I recommend using the same type as originally engineered in the design. i.e. use aluminum electrolytic to replace old aluminum electrolytic, etc. Try and get the same size and lead spacing to fit the pcb. I generally use 105 deg. C rated parts and increase the voltage rating if I can get it in the package siz I need. Also, I always buy name brand quality parts from Mouser or Digi-Key. Good luck!
 

Online med6753

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Re: Old Fluke Multimeters
« Reply #531 on: September 21, 2018, 02:22:25 pm »
Well, Flukers (is that too crude?   >:D ) it looks like I have an 8800A/AF on the way.  Guaranteed working, pictures supplied of the unit allegedly powered up and working in multiple modes.  Fingers crossed, it's supposed to arrive tomorrow.

Now, business: this, and my 8600A, are likely in ticking time bomb mode as far as electrolytic caps are concerned.  I've read almost all of this thread, and it seems maybe the aluminum poly caps are the best replacements?  How about for replacing the tantalums?  I'm putting together a BOM to get my meters updated so (without starting any arguments) what's the consensus?

My 8600A just had a major crap out due to tantalums. See here...
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg1839170/#msg1839170
An old gray beard with an attitude.
 
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Offline rsjsouza

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Re: Old Fluke Multimeters
« Reply #532 on: September 21, 2018, 02:59:08 pm »
Well, you were lucky they didn't go out with a bang and flames. :)
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Offline cvanc

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Re: Old Fluke Multimeters
« Reply #533 on: September 21, 2018, 03:30:48 pm »
The seller says there is a dim character in the display; I have not had time to read the entire thread yet so I'm not sure if that is repairable.

Quite possibly a simple fix.  Read up on cleaning the elastomeric strips (sometimes called zebra strips).  These are what connect the back of the LCD to the circuit board below.  They are a common cause of missing or faded segments.

Good luck!  (and I'm a little jealous)
 

Offline GregDunn

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Re: Old Fluke Multimeters
« Reply #534 on: September 21, 2018, 06:18:55 pm »
I'm still cross-checking the BOM before placing an order, so all input is appreciated.  I notice that Dr. Taylor chose nearly all polymer caps for his rework of the 8060s; is there a good reason why that's not an appropriate course of action for the bench DMMs as well?  I acknowledge that the big PSU filter caps might need to be Al electrolytics; but given that I am probably going to have trouble finding cheap glass-sealed Tantalums  :-DD should those still be replace with Ta or are the polys a better choice there too?

Here's a list of the caps - and original types - which I'm targeting for the 8600A, as one example:

220 µF 40V [2]
2000 µF 15V [1]
6.8 µF 35V Ta [2]
22 µF 15V Ta [1]
330 µF 3V Ta [2]
39 µF 6V Ta [1]
5.6 µF 20V Ta [1]

 

Offline GregDunn

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Re: Old Fluke Multimeters
« Reply #535 on: September 23, 2018, 08:32:59 pm »
For those who don't check all the forums each time they visit (who would do that?   ;D ) here's the story of my latest acquisition:

https://www.eevblog.com/forum/repair/fluke-8800aaf-issues/

Spoiler: it seems to be working perfectly after applying a few things I learned in this thread.  Now burning it in to be sure there aren't any more gotchas.
 

Offline Benzz

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Re: Old Fluke Multimeters
« Reply #536 on: October 09, 2018, 03:56:20 pm »
Some 8060a Flukes. These were in a junk box of a person who gave them away for very little money. None of them working properly. Will try to repair as many as possible, but it seems most of the displays are faulty, most of the housings are broken somewhere. Btw, I am not the owner, got them for repair.
 

Online tautech

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Re: Old Fluke Multimeters
« Reply #537 on: October 09, 2018, 07:09:04 pm »
Some 8060a Flukes. These were in a junk box of a person who gave them away for very little money. None of them working properly. Will try to repair as many as possible, but it seems most of the displays are faulty, most of the housings are broken somewhere. Btw, I am not the owner, got them for repair.
Welcome to the forum.

Let's hope you can specify that part of the cost of repair is to keep one for yourself.  :)
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Offline Benzz

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Re: Old Fluke Multimeters
« Reply #538 on: October 09, 2018, 07:29:39 pm »
Let's hope you can specify that part of the cost of repair is to keep one for yourself.  :)
That's the deal: repair as many as you can, keep one of your choice. That choice would be easy, only one of them is US made, all the others are NL made.
 

Online tautech

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Re: Old Fluke Multimeters
« Reply #539 on: October 09, 2018, 07:35:24 pm »
Let's hope you can specify that part of the cost of repair is to keep one for yourself.  :)
That's the deal: repair as many as you can, keep one of your choice. That choice would be easy, only one of them is US made, all the others are NL made.
:clap:
Cool, well aren't you in the right place and thread with all the info from the original designer !
And after fixing as many as you can you'll be our new resident expert !  :-DD
Avid Rabid Hobbyist
 

Offline Benzz

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Re: Old Fluke Multimeters
« Reply #540 on: October 09, 2018, 08:16:08 pm »
Oh yes, this thread started it. As I said, it was a junk box nobody really cared about. Now I found out that recapping is not very funny.
Btw, there is another toy which fortunately works quite well. For comparison a pic with a calibrated HP MM.
 

Offline lowimpedance

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Re: Old Fluke Multimeters
« Reply #541 on: October 10, 2018, 04:05:30 am »
Oh yes, this thread started it. As I said, it was a junk box nobody really cared about. Now I found out that recapping is not very funny.
Btw, there is another toy which fortunately works quite well. For comparison a pic with a calibrated HP MM.
Nice little save from land fill !, while your in 're capping' mode, you should also look inside the 8050 as there are also some small electro's that maybe starting to leak. Well worth a quick check.
I have three of these meters and all three had leaky caps.
The odd multimeter or 2 or 3 or 4...or........can't remember !.
 

Offline Benzz

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Re: Old Fluke Multimeters
« Reply #542 on: October 10, 2018, 11:08:23 am »
Yes, I think I will do that. The 8050 ist a bit slow, takes some time till the reading is stable. This is because of leaking caps, yes?
 

Offline lowimpedance

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Re: Old Fluke Multimeters
« Reply #543 on: October 10, 2018, 12:04:29 pm »
 
Cap issue aside, given that it has sat unused for a long time it would also be a good idea to 'exercise' the switches as jittery readings can be caused by oxides building up on the switch contacts.
The odd multimeter or 2 or 3 or 4...or........can't remember !.
 

Offline Benzz

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Re: Old Fluke Multimeters
« Reply #544 on: October 10, 2018, 07:30:47 pm »
Ok, the switches, thanks for the hint. That robot-deo (deoxit) will help, I hope. Ah, those long winter nights are comming, time to fix old gear...
 

Online med6753

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Re: Old Fluke Multimeters
« Reply #545 on: October 13, 2018, 11:54:53 am »
Well, Flukers (is that too crude?   >:D ) it looks like I have an 8800A/AF on the way.  Guaranteed working, pictures supplied of the unit allegedly powered up and working in multiple modes.  Fingers crossed, it's supposed to arrive tomorrow.

Now, business: this, and my 8600A, are likely in ticking time bomb mode as far as electrolytic caps are concerned.  I've read almost all of this thread, and it seems maybe the aluminum poly caps are the best replacements?  How about for replacing the tantalums?  I'm putting together a BOM to get my meters updated so (without starting any arguments) what's the consensus?

My 8600A just had a major crap out due to tantalums. See here...
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg1839170/#msg1839170

Revisiting this issue with the 8600A. It appeared at first that the drifting problem on the 20VDC range had been fixed. It wasn't. After the DMM was shut off for several hours on initial power up it was grossly inaccurate. For example: against a 9.99691V reference it would sometimes read as low 9.945V. Over the course of a half hour or so the voltage measurement would slowly increase to 9.997V and then remain stable. I finally traced this back to the DC input divider board and believe it or not it was one of the reed relays. When the relay was “cold” it had high contact resistance and as it warmed up the contact resistance decreased. And I proved it with freeze spray and a heat gun. Freeze spray would lower the measured voltage to as low as 9.7V and then apply heat and right back up to normal.

The 8600A has a total of 7 of these reed relays. 3 on the DC divider board, 1 on the Ohms board, and 3 on the AC board. I decided to change the reed relays on the DC divider and Ohms boards but for now leave the AC board alone since I don't have appropriate standards to perform a calibration.  All of the reed relays are 5 volt coil and SPST NO type and they have a finite life span which after 40-45 years has been greatly exceeded. Obviously getting exact replacements is near impossible so I had to find acceptable substitutes. One of the items that needed to be checked was coil resistance. Turns out 1 relay had a coil resistance of 125 ohms and the other 3 had a coil resistance of 600 ohms (Didn't check the relays on the AC board).

Here's the DC Divider board. The reed relay on the left is 125 ohm coil, the 2 on the right are 600 ohm coil. The defective relay (K2) is in the lower right.



The Ohm's board. The single reed relay is 600 ohms coil.



Here's what I found for substitutes from Mouser. The bag on the left is a 125 ohm relay. Mouser P/N 934-HE3351A0500. The bag on the right are 500 ohm relays. Mouser P/N 934-HE3321A0400. I could not find 600 ohm relays that were reasonably priced so I decided to go with 500 ohm. The difference in drive current is about 2ma greater and I figured it would not be an issue (Proven to be true).



Here is the DC Divider board with the new relays installed. They are a smaller form factor so they are mounted sideways against the board and held in place with 3M automotive grade emblem tape. Then leads soldered to the pins.



The Ohms board. The relay mounted the same as the DC Divider board.



The results. No more drift. Accurate results right at power up. I also did a complete recalibration of the DC volts and Ohms. If you have a vintage Fluke with these reed relays I recommend changing them out before they cause problems. My 8800A has at least 4 of these reed relays and it's on my project list to replace them. 

An old gray beard with an attitude.
 
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Offline GregDunn

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Re: Old Fluke Multimeters
« Reply #546 on: October 13, 2018, 06:13:26 pm »
Interesting!  I haven't seen this sort of misbehavior on my 8600A or 8800A; they seem to be pretty accurate within a minute or less of power-up. 

How much change in adjustment was required?  And what are you using for the DCV and resistance standards?  I don't have access to anything accurate enough to re-calibrate either of my meters to that degree of precision.
 

Online med6753

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Re: Old Fluke Multimeters
« Reply #547 on: October 13, 2018, 08:01:07 pm »
Interesting!  I haven't seen this sort of misbehavior on my 8600A or 8800A; they seem to be pretty accurate within a minute or less of power-up. 

How much change in adjustment was required?  And what are you using for the DCV and resistance standards?  I don't have access to anything accurate enough to re-calibrate either of my meters to that degree of precision.

Valid questions. How much change was required? Not much actually. Just some tweaks. The 8600A was pretty much spot on before it started acting up.

I have an assortment of references that, while not traceable, do a credible job. First, I have two AD-584M references. One as primary and one as backup. They are accurate and stable enough to check up to 5.5 digit DMM's. But they only cover 2.5VDC to 10.0VDC. I have 2 home built references for 100.0mV, 1.000V, 10.00V and 190.0mV, 1.900V, and 19.00V that are really only accurate enough to do 3.5 digit DMM's but if I monitor their output with the known accurate 8800A I can adjust the 8600A pretty much dead nuts.

I have an inverter card that generates 190.0VDC but it isn't very stable but if I monitor it with a known good DMM it at least get's me in the ballpark.

For resistance I built up a decade box of 0.1% resistors from 1.0 ohm thru 10.0MEG. Not perfect but accurate enough for me.

 
« Last Edit: October 13, 2018, 08:19:13 pm by med6753 »
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Offline bd139

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Re: Old Fluke Multimeters
« Reply #548 on: October 13, 2018, 08:43:46 pm »
I actually had one of the original relays' coils go open circuit on my 8600A. Very very annoying that was. Did the same sort of replacement.
 

Offline GregDunn

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Re: Old Fluke Multimeters
« Reply #549 on: October 13, 2018, 10:34:51 pm »
I have an assortment of references that, while not traceable, do a credible job. First, I have two AD-584M references. One as primary and one as backup. They are accurate and stable enough to check up to 5.5 digit DMM's. But they only cover 2.5VDC to 10.0VDC. I have 2 home built references for 100.0mV, 1.000V, 10.00V and 190.0mV, 1.900V, and 19.00V that are really only accurate enough to do 3.5 digit DMM's but if I monitor their output with the known accurate 8800A I can adjust the 8600A pretty much dead nuts.

I have an inverter card that generates 190.0VDC but it isn't very stable but if I monitor it with a known good DMM it at least get's me in the ballpark.

For resistance I built up a decade box of 0.1% resistors from 1.0 ohm thru 10.0MEG. Not perfect but accurate enough for me.

I have three inexpensive but calibrated voltage references (2 AD584 and 1 LM399) which I definitely trust in the range of 1-10VDC and am also preparing a resistance standard which should be good enough for the meters I currently own - that's why I was interested in comparing your methods to my approach.

I am almost finished repairing an HP6920B which I hope will be good and stable enough to at least let me sync my meters as you described.  Checking it against my Keithley and 2-Fluke bench meters it seems to be consistent if not 5-digit accurate up to well over 100V (that mechanical dial is probably the least accurate part of the unit...) and 1A. I expect I'll do a standard deviation calculation on these three meters vs. the HP and see how they line up over a wide voltage range - that should be good enough for the work I do here.  I rarely need anything better than 0.1V accuracy under any circumstances, but it's nice to have better for drift and other relative measurements.

So perhaps I should stock up on relays in my next parts order just to be prepared for the inevitable.  Have you looked at the 8800A relays yet?  The BOM indicates that the two units use the same Fluke part numbers for the relays though perhaps not the same number of them.
 


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