Fluke 8060A Calibration Service?

[thared33]

I got a Fluke 8060A multimeter on Ebay a while back. It's actually in very good cosmetic condition with a near perfect display. Everything seems to work fine except when I test for voltage or decibels. The readings are definitely off. I don't know if it just needs to be calibrated, or if it needs an actual repair. I don't want to just chunk it. I want to save and use this beautiful machine.

Does anyone know of a place or a person that I can send this into to be looked at? If it comes to it I can replace/solder some of the parts myself since I found instructions for that, but I'm not sure I have days on end to spend repairing it. I'd like to get it working in any case.

[Fungus]

What's the serial number? That gives an idea of age.

It may be that the capacitors have given up and/or leaked all over the PCB. Even if they haven't leaked they should still be replaced ASAP. Old electrolytics lose capacity, stop working and if they leak they can corrode the PCB and destroy the meter.

Calibration is easy, just connect up a voltage reference and twiddle the appropriate potentiometers. See manual for details. You could start by trying to get it to agree with another meter. If it gives you problems then suspect the capacitors.

Here's some guidance from the guy who designed the meter:

https://www.eevblog.com/forum/testgear/old-fluke-multimeters/msg1288190/#msg1288190

Part numbers for replacement caps are in the post above that one.

[drtaylor]

Most likely you have leaky electrolytic caps. There's one right next to the AC Converter that can cause ACV to be off. I assume you meant that AC Volts was off since you also mentioned dB. If DCV is reading wrong, then you have more problems. This will not be solved by calibration. Take the board out and examine around all the electrolytic caps looking for electrolyte leakage. This is all that usually goes wrong with 8060s. Mr Modemhead has well illustrated repair guides for the 8060A. I was the designer of the 8060A. You can see more discussion on the 8060 in the "Old Fluke Multimeters" topic. I have 12 8060s that all needed new caps, but are now functioning beautifully. Pretty good for a 35 year old design.

[Fungus]

Mr Modemhead has well illustrated repair guides for the 8060A.

http://mrmodemhead.com/blog/ibm-8060aaa-fluke-8060a-refurbish/

[thared33]

The serial # is 3340537, located at the top back, etched into the case. The mainboard is a revision F. How old is this one?

ACV is what I was testing drtaylor, you're right. I'm using this primarily for audio gear testing/calibration, but only simple stuff like testing output levels to make sure my studio gear is working fine. ACV and DB are definitely both off. An electrical outlet shows 143V on the 8060A but my cheap $20 Innova shows 122V which is obviously more accurate. DC is reading fine on the 8060A though. A new 3V coin battery and a new 9V battery both tested slightly above 3V and 9V, respectively.



I looked for some leakage but I'm not seeing anything too major. But I'm also not sure exactly what I'm looking for either. There is what appears to be a little EPROM type looking chip that has some green residue on its legs. It says FLUKE RMS on it and what appears to be a little drop of paint or something.

I solder mostly cables but have soldered in a couple things on boards before. If you think this is an easy fix and I can do it myself then I'll take a swing. I wish I had someone that could recap and calibrate it for me though 

[lowimpedance]

That chip is the RMS IC and the green is corrosion caused by the leaking electrolyte from that nearby electrolytic cap.
 You need to remove ALL the electrolytics and clean the PCB thoroughly to remove all traces of electrolye and corrosion, see the linked site to Mr Modemhead.
Repair any damaged traces and install new caps.

[thared33]

I'm looking at the instruction manual but the layout of the caps doesn't quite match up with my own multimeter. The manual says at the top that it's for serial numbers 6851 and higher. Mine is way lower. Is there a diagram available that shows where the caps are?

[lowimpedance]

Your meter layout is the same as the 8060a in modemheads blog, I would follow what he has done. He even lists the caps he used in the repair.  .

[thared33]

I'm not seeing a layout anywhere on his blog. I took it that I'd have to look in the manual. The manual doesn't seem to indicate where at least a couple of the caps are. For example, there is a cap directly below C36 on my meter but it's not listed in the layout which is attached, and C19 which I see on his blog is nowhere to be found in that layout either. Maybe I'm overlooking something or there was a service manual available that I need.

[thared33]

I was able to locate and remove C12, C1, C36, C23, C34, C32, and C21. I see two more caps around that RMS chip (above and below it or so) for a total of 9. I don't see those other two I'm seeing on mine in the page I uploaded. There are supposed to be 10 though so I'm not sure what I'm missing.

[Fungus]

The serial # is 3340537, located at the top back, etched into the case. The mainboard is a revision F. How old is this one?

Late 1980s I think.

If you lift the screen assembly off there will be a datecode on the chip underneath in the form WWYY (week, year).

[thared33]

It's underneath the chip? Because mine does say 1983 on it.

I spotted which cap is missing on mine. It's the one farthest to the bottom right, near those 4 white things (mine are blue). Check the attached photos to see what I mean. Mine has a little puddle of solder in both of those holes and that was definitely done at the factory. I'll have to get someone to chime in and see what's going on with that.

I have a new batch of IPA on the way as well as all the caps from Digikey. Just need to be filled in on which caps go where as mentioned earlier.

[Fungus]

It's underneath the chip? Because mine does say 1983 on it.

0890 = Week 8, 1990

[thared33]

Mine says:

FLUKE
612713
1983
241E

[Fungus]

Mine says:

FLUKE
612713
1983
241E

Is that photo of your meter?

[ModemHead]

I spotted which cap is missing on mine. It's the one farthest to the bottom right, near those 4 white things (mine are blue). Check the attached photos to see what I mean. Mine has a little puddle of solder in both of those holes and that was definitely done at the factory. I'll have to get someone to chime in and see what's going on with that.

C28 is a 10uF across the 1.2V bandgap reference.  To be honest, I hadn't noticed that it disappeared at some point in the lifespan of the design.  I have hardcopy documentation from 1983 and 1988.  C28 exists in the 1983 rev, but is not mentioned in the 1988 and the much-later PDFs available on-line from the Fluke archives.

If it is not in your meter then there should be no need to include it.

On a side note, just a few days ago someone asked me about schematics for the older RMS converter section.  I scanned a few key pages of my 1988 manual and made it available in a zip file:
8060A_Rev3-0188_Manual_Scans.zip

For completeness, I probably should repeat the exercise with the oldest hardcopy I have, which is a 1983 manual for the IBM 8060A/AA.  It does include C28.  I'll add the link here when finished.
8060A-AA_Rev1-0183_Manual_Scans.zip

[thared33]

Mine says:

FLUKE
612713
1983
241E

Is that photo of your meter?

Mine was posted earlier. The other one I took from Modemhead's blog.

Modemhead: Are you sure that cap disappeared later on? Because if the date on my chip is correct (1983), very early models might not have come with it. It seems like later models didn't either though, if your documentation is accurate.

I got all 9 of the caps out. A few have crust on the holes so I'll clean them with IPA and resolder everything when my digikey package gets here. The ICL7660 looks fine but I haven't tested it. The 40-pin socket looks fine too. The only thing I'm concerned about is that there is green stuff on that RMS chip's legs. I hope a good scrubbing is all it's gonna need.

I'll update the thread when I get the good caps in there in a few days.

[ModemHead]

Modemhead: Are you sure that cap disappeared later on? Because if the date on my chip is correct (1983), very early models might not have come with it. It seems like later models didn't either though, if your documentation is accurate.

No, I can't be sure.  All I know is that C28 appears in the oldest documentation I have (the 1983 IBM 8060A/AA manual), and is not present in any later docs that I've laid eyes on.  It has been physically present in the units I've recapped, which are all fairly old, serial numbers starting with 3 or maybe 4.  So I hadn't noticed its possible absence before.

A curious person might ask why the unit I was re-capping that is shown in the photos above has a MAC chip with a 1990 date code.  Since the other chips have 1982 date codes, I'm guessing the MAC chip was replaced at some point.  It previously belonged to a retired IBM tech so I don't know its history.

[Fungus]

Mine says:

FLUKE
612713
1983
241E

Is that photo of your meter?

Mine was posted earlier. The other one I took from Modemhead's blog.

OK, I was confused by all the photos. I'd expect a 1990 meter to have a number that starts with a 4, not a 3.

A curious person might ask why the unit I was re-capping that is shown in the photos above has a MAC chip with a 1990 date code.  Since the other chips have 1982 date codes, I'm guessing the MAC chip was replaced at some point.  It previously belonged to a retired IBM tech so I don't know its history.

Ok.

The only thing I'm concerned about is that there is green stuff on that RMS chip's legs. I hope a good scrubbing is all it's gonna need.

Probably a copper salt. Try warm water, a cotton bud and plenty of elbow grease (it can take a while to dissolve).

[thared33]

The AC voltage reading isn't working at all after recapping. An electrical outlet won't give a reading and only goes to 0.02V. When I power it on while holding the continuity button I get about 99.95, so that's a good sign I think.

[retiredcaps]

I would double check your soldering and check you didn't install a capacitor backwards or something.

Check the Switch Decoding Self-Test and see if ACV works properly.  Page 5-22 shows the procedure.  In addition, go through the voltage test AC troubleshooting guide  and check the test points documented.

[retiredcaps]

On my used Fluke 8060A that I bought off ebay, it wouldn't even power up due to leaking capacitors.  After I replaced them, AC was off.  Some electrolyte had leaked into the legs of the AC pot.  I turned the AC pot all the way to left and right three or four times and then adjusted it.  Turning the pot I suspect helped remove some of that electrolyte that had wicked up?

[thared33]

All numbers on the switch test are coming up normally. I don't think there is an issue with soldering, but I'm going to double check and maybe resolder a point or two if I have to. All caps are installed in the proper polarity for sure, as I can tell by comparing Modemhead's cap positions.

I'm looking at the test points from the documentation Modemhead provided but I'm not really finding the right place to test, since I'm not very knowledgeable about this kind of stuff. I'm spending hours trying to fix it, so if it doesn't work out soon I think I'm better off just buying a newer multimeter since this isn't worth my trouble.

EDIT: I looked for this AC pot as you say but I can't find that either. Is there an actual service manual that's different from the user's manual? Not sure it matters at this point because I really don't want to fool with it any more. Maybe you experienced tech guys can fix this easily, but this is becoming way over my head.

[ModemHead]

The AC voltage reading isn't working at all after recapping. An electrical outlet won't give a reading and only goes to 0.02V. When I power it on while holding the continuity button I get about 99.95, so that's a good sign I think.

9995 on the ratio test does indeed mean the ADC is working, which is a good thing.

DC volts and ohms are working OK, but AC volts is not, is that correct?  If so, then I have some basic RMS converter trouble-shooting suggestions you can work with.  Voltage measurements are made with respect to the 8060A COM jack.

• Set the 8060A to 200mV ACV range.
• Connect a stable AC source of 190mVrms, sine wave, 200Hz to the 8060A input jacks.
• Measure the AC voltage at U2P5.  It should be a little less than 190mVrms, due to loading from the working DMM's input impedance.
• Measure the DC voltage at U2P10. It should be about -190mV DC.

If you do not have a signal/function generator, a function generator app running on a phone/tablet will work for the test signal source.  Connect one channel of the device's headphone jack to the meter.

[thared33]

Is there a service manual that I'm not aware of? Because I keep seeing hearing about places to check on the meter's board but I have no idea how to locate them. From what you say I think U2P5 and U2P10 means the RMS chip, and pins 5 and 10. Not sure how the pins are numbered. (Note: that green stuff never came off the RMS chip, so maybe that's the problem...)

Forgive me for asking such rudimentary questions, but:

There's a positive and negative side of a balanced cable that I can run out of my audio interface to get .190V. I also have a Leader 192A sitting around, and it has a red terminal and a black terminal (I guess red is positive and black is negative?). If I get one of those set up with .190V, should I run the positive side to the red input on the 8060a and the negative to the COM jack?

After that's set up I can use my other cheap Innova meter to test once I find the right pins. There's a red and black cable for it just like on the 8060a, and I think the red one will go on the pin, but where should I stick the black one?

I appreciate everyone that has taken time. I know it's a hassle to teach an ignoramus