Author Topic: Old Fluke Multimeters  (Read 218626 times)

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Offline Dave Wise

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Re: Old Fluke Multimeters
« Reply #650 on: February 13, 2019, 05:58:18 pm »
I was given an 8100B, a smaller 4-1/2 digit model in this product family.  It seems to work but reads about 7 counts high (i.e., positive offset) regardless of mode, range, or measurand amplitude or polarity.  I'll calibrate it when time and mood coincide.  In the mean time, do you think this is a straightforward zero adjust, or one of the other less obvious trims like A/D Offset or Remainder?

And it's funny - it has Option 001 (battery) but there's no evidence there was ever a battery pack installed.  What's the story behind this, do you think?

Dave Wise (ignore typo in userid)
 

Offline joeqsmith

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Re: Old Fluke Multimeters
« Reply #651 on: February 14, 2019, 12:35:06 pm »
Interesting. I was curious about the original prices too. Even $299 USD for a 8000A was big bucks back then. (That's almost $1600 USD in today's dollars)

That list is too early for the 8010A and 8050A which came out quite a few years later, not until the 1980's. They would be probably roughly equivalent to the 8000A and 8600A in price although the 8050A doesn't have auto ranging.

I recently posted a video comparing my first digital VOM, an 8000A, with a free meter from Harbor Freight.  I show a 1974 magazine with the cost.  Indeed, $299 back then.   

How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline Dave Wise

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Re: Old Fluke Multimeters
« Reply #652 on: February 14, 2019, 10:25:47 pm »
Quote
Dave, report your or my post to a moderator and ask nicely for them to correct your user ID....it can be fixed.
Thanks, Tautech, I did.
 

Offline bitseeker

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Re: Old Fluke Multimeters
« Reply #653 on: February 15, 2019, 01:51:33 am »
Looks much better, Dave, and welcome.
I TEA.
 

Offline scopeman

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Old Fluke Multimeters Series 70 Rotary Switch needed
« Reply #654 on: March 14, 2019, 01:29:25 am »
Hello,

I have a Original Fluke 77 that has a mangled rotary switch (the electrical wafer rotary switch on the PCB not the knob in the case).

Does anyone know where I can find one of these or does anyone have a scrap PCB that I can recover the switch deck from?

Thanks for reading!

Sam
W3OHM
Owner/Moderator of the LeCroyOwnersGroup on groups.io
 

Online bd139

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Re: Old Fluke Multimeters
« Reply #655 on: March 14, 2019, 01:36:13 pm »
That's what spelled the end for my 77. I sold it on ebay then as I couldn't find parts. It might be worth buying a physically damaged one and using the insides of that with yours. There are plenty out there with cracked casing etc which have good switches still.
 

Offline TubeDoc

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Re: Old Fluke Multimeters
« Reply #656 on: March 22, 2019, 04:00:00 pm »
I am relativly new to this blog, but have enjoyed the information traded here, esp the histroy of the early Fluke multimeters. 

I, too am a bit of a meter junky.  I have a good example of all but a couple of the 8020 series of meters up through the 8060s, with a few odd meters good for parts, etc.  I have a few 8800As or 8810As that light up and measure but that have problems with ranging, etc. I also have some miscl buttons, knobs, etc. for 8000s and 8600s.  I would happily swap the bech meters for something else.  I'm not sure of the ettiquite or mechanics for swaping parts here.

Thanks again for the great information and enthusiasm.   

Rob
 
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Offline Neomys Sapiens

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Re: Old Fluke Multimeters
« Reply #657 on: March 22, 2019, 10:54:43 pm »
I am relativly new to this blog, but have enjoyed the information traded here, esp the histroy of the early Fluke multimeters. 

I, too am a bit of a meter junky.  I have a good example of all but a couple of the 8020 series of meters up through the 8060s, with a few odd meters good for parts, etc.  I have a few 8800As or 8810As that light up and measure but that have problems with ranging, etc. I also have some miscl buttons, knobs, etc. for 8000s and 8600s.  I would happily swap the bech meters for something else.  I'm not sure of the ettiquite or mechanics for swaping parts here.

Thanks again for the great information and enthusiasm.
There will be a dedicated thread for T&M 'parts mules' shortly. Keep looking for that and list yours then.
 
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Offline imaradiostar

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Re: Old Fluke Multimeters
« Reply #658 on: April 28, 2019, 01:05:38 am »
I've really enjoyed reading this thread. I have two 8060's - one that's early and has been recapped, and one that's a much later unit and doesn't appear to need recapping...YET.

I purchased the recapped unit on eBay and found that the MAC socket was damaged but not replaced. I replaced it and cleaned the board (IPA and ultrasonic cleaner) while I had it apart. I also dunked and cleaned the MAC chip with alcohol as I found some green junk on the pins. After thorough cleaning it passes ADC self test with a correct count.

I have an HP 3456a and an Analogic AN3100 DC standard, and an assortment of other multimeters, including a few 8050s. I can tweak any of them to match across each range, but the recapped 8060a still drifts a bit and overnight it no longer matches the other meters, off by a count of 40 or so while the others still match. I've also found that if I tweak it to read 0.1900vdc or 1.9000vdc correctly, it doesn't scale to lower voltages correctly while the others all easily meet spec.

Is it fair to assume there is still junk on the board or MAC somewhere causing the incorrect scaling? What should I look for?

I have an additional IBM unit that doesn't work and if I'm going to order parts to rebuild it I might as well order more spares!

Thanks!

jamie
 

Offline retiredcaps

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Re: Old Fluke Multimeters
« Reply #659 on: April 28, 2019, 02:03:04 am »
Is it fair to assume there is still junk on the board or MAC somewhere causing the incorrect scaling? What should I look for?
Did you check the bottom bung of the electrolytic caps?
 

Offline imaradiostar

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Re: Old Fluke Multimeters
« Reply #660 on: April 28, 2019, 02:31:18 am »
Truthfully, I read on eBay that is was recapped, saw recent soldering and flux, and didn't check all of them. I don't wish to throw the seller under the bus but it wasn't to my usual level of craftsmanship. At this point I'm tempted to simply redo it. There's no point in having a high count meter that isn't as accurate as my Chinese amazon cheapies!

I guess it makes sense to order three sets of caps and various other bits and hunker down for some rebuilds. I have a nice Pace sodr-x-tractor and the work will go fast.

JT
 

Offline retiredcaps

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Re: Old Fluke Multimeters
« Reply #661 on: April 28, 2019, 04:25:44 am »
Is it fair to assume there is still junk on the board or MAC somewhere causing the incorrect scaling?
It might take several applications of IPA and cleaning? See

http://mrmodemhead.com/blog/fluke-8060a-repair/
 
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Offline imaradiostar

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Re: Old Fluke Multimeters
« Reply #662 on: April 28, 2019, 05:05:42 am »
You're probably right. It's been a while since I read that blog post. Even though the meter was supposedly refurbished, it's silly not to dig in a clean it again, and possibly swap the MAC with a meter that functions correctly to see if the problem follows.

Knowing myself and the likelyhood that any older 8060a would have bad caps and related problems, I sortof regret buying one that's "refurbished" for decent money when I already have the charge pump and machine pin sockets on hand, and the caps are cheap. I have no doubt that I can put it right, only I have little time right now to do it.

I have three 8050a's, an 8060a, and a modern Owon B41t+ apart on my bench, and I just purchased a used Fluke 187 for use at work without knowing if it functions correctly. I have the IBM 8060a and an additional 8050a apart at work. Too many projects! I enjoy the distraction, though. Somehow messing with multimeters scratches some sort of OCD itch and I find it satisfying.

oh yeah, I have an HP 3478a apart, too. Needs a power transformer. Neat meter, though. Oh, and an 8920a that reads off by about 20%. Found some caps with high ESR, but no smoking gun yet.

Yeah, it's a sickness. I think there is a thread for that.

Jamie
 

Offline GregDunn

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Re: Old Fluke Multimeters
« Reply #663 on: May 18, 2019, 11:56:21 am »
The "addiction" continues...  I found a nice clean 8600A at the Dayton hamfest yesterday for $20.  Using my 10V standard, MC-7 precision resistor set and HP 6920B it measures very close on all functions and ranges.  I always take these apart to make sure there's nothing questionable going on inside, and this time I see that a previous owner replaced some components (U4-5 seem to have been the target) because there is a lot of flux residue. 

U4 is supposed to be a LH0042C so I could check to see whether the sub is appropriate, but U5 is listed only as Fluke PN 385450 which is generally referenced to an AD40323.  Both are of course selected for (I assume) leakage or offset; but right now U4 is an AD40291 and U5 is an AD40420 and I can't find any data for any of them so far.

I suppose I shouldn't worry about it - the meter is rock stable after about 5 minutes of warmup and seems to be well within spec.  But I'd really rather have some more info because if one of these goes bad on another meter... well.
 

Offline bob91343

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Re: Old Fluke Multimeters
« Reply #664 on: May 18, 2019, 05:43:21 pm »
Do you want to foist that 3478A on someone who might try to repair it?  That would be a fun project for me.
 

Offline imaradiostar

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Re: Old Fluke Multimeters
« Reply #665 on: May 18, 2019, 05:47:00 pm »
Sorry, it's a company asset, can't sell it!

JT
 

Offline elecdonia

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Re: Old Fluke Multimeters
« Reply #666 on: May 26, 2019, 06:18:35 pm »
I may be able to provide some info about op-amp substitutes that work well and perhaps even improve the accuracy and stability. I own an entire shelf of 8600A and 8800A. Many different vintages. I was able to get most of them to exceed specs. It’s somewhat unusual for these op-amps to fail.

I also converted a very rough 8800A into a programmable DC preamp with extremely high input impedance and the capability to handle +/- 20V inputs. I use it as a front end for logging devices based on Raspberry Pi and/or Arduino hardware.

 

Online med6753

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Re: Old Fluke Multimeters
« Reply #667 on: May 26, 2019, 06:55:49 pm »
I may be able to provide some info about op-amp substitutes that work well and perhaps even improve the accuracy and stability. I own an entire shelf of 8600A and 8800A. Many different vintages. I was able to get most of them to exceed specs. It’s somewhat unusual for these op-amps to fail.

I also converted a very rough 8800A into a programmable DC preamp with extremely high input impedance and the capability to handle +/- 20V inputs. I use it as a front end for logging devices based on Raspberry Pi and/or Arduino hardware.

OK, I'm game. I own both an 8600A and an 8810A. What op-amps do you recommend changing and with what type? 
An old gray beard with an attitude.
 

Offline GregDunn

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Re: Old Fluke Multimeters
« Reply #668 on: May 26, 2019, 07:12:30 pm »
I'd be interested too.

I suspect this meter met with an "accident" because there were a few components in the input section which had telltale flux residue (and lots of it) on their pins.  I doubt any of my 8600s will have a similar failure, but it's good to know as much as possible about the hardware requirements just on G.P.
 

Offline Pablitox

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Re: Old Fluke Multimeters
« Reply #669 on: July 05, 2019, 02:05:06 am »
Eh acquired a fluke 8060a Ibm.  I read the Mrmodemhead Guide and looking for the C28 capacitor my board does not have it.  It has the through holes but there are no signs that that component has been removed there.  Why?
 

Offline Electro Detective

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Re: Old Fluke Multimeters
« Reply #670 on: July 05, 2019, 02:55:48 am »
That's a weird one and looks to me like there was a cap there 

Maybe the board had track issues and cap soldered somewhere else?  :-//

or maybe it was a leaker and someone plain forgot to get around to getting the part,
and because the meter 'apparently' worked fine without it, why bother..  ::)

Check to see if any other mods done before considering to replace it,
and wait for some better/reassuring info here  :phew:
« Last Edit: July 05, 2019, 02:59:44 am by Electro Detective »
 
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Offline imaradiostar

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Re: Old Fluke Multimeters
« Reply #671 on: July 05, 2019, 03:24:13 am »
Yeah, I agree. I just checked my (yet unrestored) 8060a/aa and it for sure has a 10uF cap there. Your picture looks to have some sort of schmoo on the board where that cap should be, so maybe one leaked. Mine is a lowish SN starting with a 3 and many of the caps were leaking and the board was damaged. I would assume it needs that cap, though I can't seem to find it on the schematic!

Jamie
 
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Offline drtaylor

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Re: Old Fluke Multimeters
« Reply #672 on: July 05, 2019, 05:17:46 am »
C23 is a filter cap for the digital supply to the SM4. I advise it is put back in. C24 is a filter for the LCD duplex divider reference. The original missing cap obviously spewed electrolyte and the area should be thoroughly cleaned. Also it looks like enough corrosion on the traces occurred that will require careful work to ensure the cap is connected.

It is often true that the effect of some filter caps is not apparent, but in order to maintain a digital supply that did not cause noise in the TRMS section, C23 is needed. The digital supply can add noise to low level AC readings due to fluctuating currents while processing.
 
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Offline Pablitox

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Re: Old Fluke Multimeters
« Reply #673 on: July 05, 2019, 05:43:29 am »
The image I used was of mrmodemhead.  This is the plate of my multimeter.  It is somewhat blurred.  Sorry for my lousy English
 

Offline vinlove

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Re: Old Fluke Multimeters
« Reply #674 on: July 05, 2019, 05:48:08 am »
I have an old Fluke 25, and it still works fine.  Will never rid of it.
When PSU amp measuring, it beat modern Chinese DMMs in accuracy.

It is simple and heavy, but keeps going.
 
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