Old Fluke Multimeters

[ChasL0001]

Hi All
Just bought three Fluke D8000As off ebay, for fun to get working.
Two are rev 3001 and one is rev 3011 and appears to have space for two batteries where the rev 3001 only has space for one.
I got one working of the 3001s OK but the other, whilst it appears to be in good condition, it's been robbed of two ICs, U4 - 7614 and U3 - 7617. Cant find any specsheets for these and the manual just gives fluke p/n for one of them.

Anyone know what these chips are and where to get them?

The third meter, rev 3011, has different chips for these - U4 - 7916 and U3 - 7941 - i suspect they may be similar or just older versions of the same type of chip but I dont want to chance putting them in.

Cheers
Chas

[Zoli]

Some time ago I've bought an 8060A as parts only(Rev.G, NL made 1984); here's a short history of fixing it:
Former repair attempt failed left a couple of shorts; once the shorts removed, the LCD came back to life. Proceed with the capacitor exchange - the LCD support parts are broken in two location.
Time to fire up the tools of trade: Dremel 4000, Vertical tool stand and 0,5mm cabide drill.
I've glued the broken parts together with cyanoacrylate, then proceed with drilling. The 0.45mm thick wires are leftover from the 10µF capacitors.
After drilling I've applied some CA on the top of the hole, and moved the wires in-out a couple of times, to ensure that the CA goes all the way down the hole.
After that , I've applied a drop of accelerator on the CA, and put it aside for 24h. During that time the PCB's and the MAC get washed and dried.
Next day assembly, testing - almost spot on; currently tested the low voltages(AC-DC) and ohms; no adjustment needed.
Thank you for your time, and feel free to ask questions.

[NoisyBoy]

I decided to add another DMM I used way back in the college days to my addition to go along with the 8000A I restored.  This time, I bought a 8600A.  The meter arrived filthy dirty and displayed 1.8888 in all functions and ranges after a minute of warmup, the saving grace is the printed legends for 20MOhm and 200mV on the display were all excellent without fading.  The caps were all measured in spec, but I ordered replacements just in case.  The inside of the meter was pristine, as I had to break an fluke calibration sticker back in 1980 to get to the screw to open up the case. 

Anyway, I started with reseating all the ICs, there was no change.  I then removed all the cards and cleaned the contacts with DeOxit D100, as well as adding DeOxit to each switch.  After letting it sit for 30 mins, as I exercise each switch, I saw the display began to return to near 0 with a shorted input.  After another 10 min of round robin switching, the displayed settled to reasonable numbers.

Then it came time to adjustment and calibration, I used my EDC522, IET 1433 and a function generator, after tweaking for an hour, I was able to bring everything back within spec.  The auto ranging works perfectly, and delivers DC accuracy under 0.02% error.  I did notice the design allows a little bit more ripple in its 5V supply relative to the -15/+15V supply, the new caps may be able to improve on it.  But for now, I am happy it is back in full health, so I will leave it original until there is a need to refresh components. 

For those of you who intend to restore another 8600A, the manual does not match my version of the PCB, some test points simply do not exist on my board and I had to read the schematics and PCB traces to identify them, but it was not hard to do.  I think it can serve the basic measurement need in a nostalgic fashion when utmost accuracy, speed, and automation is not required, I am just glad to see another bench meter with red glow on my test rack and bringing back warm memory of my college years.

[jmczaja]

Hi! I've been using my 8060A since my dad gave it to me in the early 90s to repair tube amplifiers and build other audio related gear. Over the years, I've acquired some fancy meters but always return to my 8060A. It still works great after all these years but obviously needs a recap at this point since it still has the originals in place. This thread has been super helpful in that respect. I was wondering if anyone had a spare light tan button (AC/DC selector) as mine has cracked off and has been lost sometime in the last few decades. I should probably buy a parts 8060A at some point to have on hand but don't think it's necessary since this one is still working great with the exception of the missing button. I will gladly pay for the button and shipping if anyone has one to spare. Drop me a PM and let me know. Thanks in advance! The 8060A is such a great meter.

[MarkKn]

In the 1980s, I bought a fluke 37. I was a hobbyist and young, so I didn't have a lot of disposable income, so I went after what I thought was the best value/functionality combination in my budget range.

My thought on this was that it looked like a bench meter, but the price reflected it was a really handheld in a large case. I was working on audio gear and I noted it speced as being able to accurately read ac up to 20khz... A while back, I became concerned about its accuracy, and some of the lcd elements were faded, so I put it on the museum shelf. Recently I saw a youtube video where someone fixed the lcd issues. I figured I had nothing to lose so I took it apart and performed the delicate surgery of cleaning that foam-based pressure connected contact mesh that powered the display, and after a very fussy assembly process, the display shows all elements full strength. So, it was fun getting that thing back to full speed.

I also had dropped it at some point and some of the plastic case parts were broken--it was not noticeable when using the case, but I glued those back in place as well.

Sure got plenty of use out of it back in the day... Many thanks to whomever showed how to clean that foam contact matrix or mesh or whatever it is.

[Fungus]

...that foam contact matrix or mesh or whatever it is.

"Elastomeric connector", aka "Zebra strip".

The Fluke 37 is definitely the coolest meter ever.

[BillyO]

My 8024B died an ugly death recently but my 8010A is still working great.  It's accuracy is astonishing.  It agrees 100% (to limit of resolution) to my newly calibrated Siglent SDM3055X and my Brymen 786..  The 8024B was not as accurate, but I miss it nonetheless.

Yeah, these old Flukes stand the test of time for sure.

[Paceguy]

I have numerous Fluke multimeters, but some of my favorites are the 8100A and 8200A. Nixie tube displays are interesting.

[cdrat]

I have a 1986 8060A that I am recapping and I noticed that the capacitor C19 was put in backwards. I have attached the photograph as received and after I removed it to show the "+" sign. Photos Below.

Then I saw this post"https://www.eevblog.com/forum/testgear/fluke-8060a-repair-doa-meter-brought-back-to-life-pictures/

And I realized that I was not alone. Same exact yellow capacitor, installed "backwards". I checked the original capacitor (which was still OK, and the stripe does denote negative)

Other photos (like from Mr ModemHead) show the capacitor in the correct orientation. http://mrmodemhead.com/blog/fluke-8060a-repair/

I am in the middle of recapping this and using the "wrong" "as received" orientation. Soaking in IPA now for refurbishing tomorrow.

I checked the schematic and it reflects the orientation printed on the board. This is part of the TRMS Converter which is not on the later versions.

Anyone know anything about this?

[yo0]

I have 3 fluke dmms 8010a, 8012a and 8050a, all working good in all functions except diodes check, all show higher than normal readings, any idea? All with 1n4148 under test.

Best regards.

Pio

[rsjsouza]

I have  also found the same scenario. I ended up leaving my cap in the same position as assembled. 

Ok, so I cracked open my two Flukes:

The 8060A (serial number 4245166) has a Siemens orange capacitor (!) that I replaced a few years ago - either I had nothing better on hand or had a mental fart. Negative points to the display, therefore I suspect I followed my golden rule to never trust the silk screen (I have been bitten before).

The 8062A (serial number 4210192) has the original yellow capacitor. Negative also points to the display. I will replace and, in the light of all this, I will probably keep the assembled polarity instead of the silk/schematics one. Not only there is a chance the bias voltage is too small to make a difference, but the weight of 30, 35 years of continuous operation without fail are enough for me to make a decision.

[cdrat]

"I have  also found the same scenario. I ended up leaving my cap in the same position as assembled."

Thanks, that is reassuring, I don't want to mess this up!

[robert.rozee]

the orientation of C19 seems to have been variously discussed for years. has anyone hooked up a scope across the cap and checked what sort and polarity of signal is presented to it in actual use?


cheers,
rob   :-)

[Fungus]

the orientation of C19 seems to have been variously discussed for years. has anyone hooked up a scope across the cap and checked what sort and polarity of signal is presented to it in actual use?

This.

We're in a forum full of test gear nutcases. It seems like it would be really easy to just measure the voltage across the thing instead of all this finger-crossing and hoping.

[J-R]

I have 3 fluke dmms 8010a, 8012a and 8050a, all working good in all functions except diodes check, all show higher than normal readings, any idea? All with 1n4148 under test.

Best regards.

Pio

I have a Fluke 8050A and it reads high as well.

[bdunham7]

I have 3 fluke dmms 8010a, 8012a and 8050a, all working good in all functions except diodes check, all show higher than normal readings, any idea? All with 1n4148 under test.

What do you get if you use the 200K range instead of the 2K range for the diode check?

[mqsaharan]

I also have an 8060A with Rev H board. About 5 years ago, during recapping I forgot the orientation of C19 and got confused if it was installed backward or not so I installed it as per schematic/silk screen. Today, after seeing another message regarding C19 I remembered that I never actually checked it.
During checking this thread for 8060A pictures for C19 orientation, I found Mr. Taylor's post #871 saying that there could be small reverse voltage possible (https://www.eevblog.com/forum/testgear/old-fluke-multimeters/msg4045864/#msg4045864). So, I finally hooked it up to my 1054Z and got the following readings:

Please take the following readings with a grain of salt. And do your own research before changing the orientation of the capacitor.

Voltage at C19 with +ve terminal pointing towards the display (installed as per schematic/silk screen)
Voltage shown are measured using Min function on Vertical menu. Just to be clear the following figures are the lowest peak of the waveform. The rest of it was above 0. I forgot to add that the scope channel was DC coupled with probe set to 1x and bandwidth limit was off. Timebase was 20ms/div. I was so hung up on keeping the probe on the board steady with one hand and not letting it slipped, I never carefully noted the peak to peak voltage of the waveform at C19 terminals. Neither I noted the V/div scale. I think it was 20mV/div but I am not sure. And peak to peak voltage were about 40mV or there about. It was fresh in my mind then but not anymore.

AC function OFF = +1.6 mVDC (mostly scope's own noise, I guess)
AC function ON = +1.6 mVDC (same as above)
   with cables attached = -36mVDC (no input signal)
   with 100V ac applied from an isolation transformer. The waveform at the capacitor terminals matches the input waveform (because I got a clean 50Hz signal there).
750V range = -1.2mV
200V range = -1.8mV
20V range = -23.2mV (OL)   (Waveform amplitude decreased)
2V range = +368mV (OL)   (I think at 2V range, waveform became triangular, instead of sine. Meter was in overload condition as in 20V range.)
200mV range = +4.00VDC (OL)   (A steady DC 4.00V)

The results were almost repeatable with +/- 1.0mv (approx).

After seeing the waveform on scope, I am glad I installed the capacitor as per schematic/silk screen.

As per the advertising material shared by Mr. Taylor in post 49 (https://www.eevblog.com/forum/testgear/old-fluke-multimeters/msg323088/#msg323088), this capacitor (C19) is installed between inverting terminals of two input opamps.

Edit: Added/updated a few details.

[BillyO]

Perhaps replacing it with a non-polar capacitor would take the confusion away.

[yo0]

I have 3 fluke dmms 8010a, 8012a and 8050a, all working good in all functions except diodes check, all show higher than normal readings, any idea? All with 1n4148 under test.

What do you get if you use the 200K range instead of the 2K range for the diode check?

16.93 kohm

Best regards

Pio

[Zoli]

Perhaps replacing it with a non-polar capacitor would take the confusion away.

The caps which I would use are 47µF@25V X7R 2220 TDK transformed in THD, which have practically no capacity loss between 0-5V; best of all, it fits.
Alternative is the 2X22µF/16V film 2220 Rubycon(still fits), four times the price of the TDK, which is five times the price of the Al-poly(~$1).
So yes, is possible to replace C19 with with proper non-polar caps; the question is if it's worth it financially.

[bdunham7]

16.93 kohm

I've never paid attention to the supposed diode function on these, but I did remember that they don't use a constant current setup for the ohms functions.  They use a voltage source and a comparison to a reference resistor plus some math.  I have no idea how this would give you a workable diode check using the resistance range (as is done properly with meters like the 8840A/AF/8842A series).  At best it might be some sort of approximation that is in the ballpark at typical diode voltages.

I dragged out my 8050A (repaired/restored and calibrated) and tried it and I got results similar to yours.  According to the manual, the 2K, 200K and 20M ranges are all usable as diode test ranges.  An ordinary diode (1N4xxx) gave me a ~0.65 on the 2K range, ~16.xx on the 200K range and ~0.81 on the 20M range.  Testing with a voltmeter during the tests gave me ~0.55V, ~0.40V and ~0.23V respectively.  Testing the current put out by the 8050A in the 2K range gives me 1.00mA shorted and 0.83mA with the diode.  That all seems similar to your results.  Unless there is some trick I don't know about and can't find in the manual, the diode test functions on these meters range from a rough approximation to plainly not working.  In theory this could be compensated for internally with math, but I see no reference anywhere to this being done and no combination of button pushes that I tried made it happen.

I've no idea how something like this made it out the door, but I suppose the feature isn't entirely unusable if you mentally correct or just want go/no-go results.  Perhaps we should all mail our meters back to Fluke and ask for refunds!   

[adinsen]

This is my first post, but I'd like to express thanks to people participating on this thread as I recently got myself a Fluke 8060a from a retired radar engineer who had kept it as his backup DMM to a Fluke 75. The 8060A hence had very little use since new in 1985. Apart from some weak segments on the display and missing original probes, the meter seemed complete, functional, and clean when I picked it up. It came with an original flyer-style danish instruction booklet, but no other documentation. I learnt from this thread to expect leaking capacitors, so I was expecting the worst when I took it apart as I got it home on the desk. Impressively, all electrolytes seemed intact, though.

I'm grateful for all the advice from people here, especially of course to DrTaylor for sharing your stories and knowledge about this fine DMM. I have just finished recapping and impressively found all the old capacitors to still be within specs in regards to capacity! Probably a sign of the fact that the meter has seen very little use and has been kept stored in the cold Scandinavian climate. I'm of course also grateful to the seller who decided to part with this DMM, his backup "Rolls Royce of multumeters"   

I chose new electrolytes based on fit/size and availability from my local Danish components vendor. In case someone reads this who is in or near Denmark, here's a list of currently available perfectly fitting miniature electrolytes from EL Supply. Note that these are generally 1000-2000h devices, but for my hobby use of the meter, I think it will be fine for 10+ years 

Designation	Original value	EL Supply P/N	Pin spacing	Diameter	Height	Description
C1,C23,C24,C32,C34	100UF 6.3V	211D3101L	2.54	6.40	7.80	RND Components 100UF 16V 105deg
C12,C21,C28	10UF 16V	211E2101L	2.00	4.00	7.50	JAMICON SS 10UF 35V 85deg
C36	22UF 16V	211E2221L	2.54	5.00	7.50	JAMICON SS 22UF 35V 85deg
C19	47UF 10V	211D2472	2.00	5.00	7.00	RND components 47UF 16V 105deg

Finished meter after recapping and cleaning of the zebra strip:


There's a few more pics in my Flickr in case anyone would like to see a bit more of the meter or share a comment/advice on my work

[ogdento]

Love seeing all these still-working 8060s!  A bit over 2 years ago I started messing around with a replacement display for the 8060...

I had another thread with a couple of hair-brained ideas that never quite got off the ground, including an oled mod and a sandwiched pcb design that were inspired by Dmitri's work over at Modemhead's blog and Bobricius over at Hackaday.  In any case, the tiny smd leds were just too fiddly to work with (for me anyway), and I'd long nixed the oled mod as impractical... a remaining option was to design a custom lcd, so I did that!!

Here's how it came out... pardon the crappy photo-work

Started off with that nasty bleeding...


And with my custom lcd...


I didn't out-right copy the original display graphic (I presume done by Dave Taylor?) because it somehow felt like cheating and possibly unethical/illegal?  I wanted to do my own art-work anyway so I made a few tiny tweaks... the digits are a touch larger and I moved the continuity bar down a hair so it would be easier for my aging eyes to see from distance.  Still got a little more fiddling to do because I screwed up the elastomer size a bit so I'm waiting on replacements, but I'm getting there!

[ogdento]

oops, I'm not qualified to operate image attachments... missed the best images of all!

[rodcastler]

 Good job on the LCD!  Looks really nice. I always liked the proportion of the digits on this fluke, but I can definitely get used to the larger ones.

I can also relate to the effort of bringing the continuity bar a bit lower as it’s hard to see. Do you happen to have a photo with the bar and the case on for comparison with the original?

I’ve read that these meters tend to suffer from bleeding LCDs just as yours. Do you plan to sell some for those of us who’d like to keep a replacement?

Thanks!