Old Fluke Multimeters

[e-doc]

Can you help me please to fix offset error on an old Fluke 8060A?

On shorted input the display shows following offsets:

Code: [Select]

range     offset
200mVDC  -0.14
2VDC     -0.0002
20VDC    -0.18
200VDC   -0.14
1000VDC  -0.14

200mVAC   0.15
2VAC      0.0051
20VAC     0.14
200VAC    0.14
1000VAC   0.14

200Ohm   -0.14
2kOhm    -0.013
20kOhm   -0.11
200kOhm  -0.11
MOhm     -0.07



I found a leaked electrolytic capacitor (C12, 10uF, 16V) and the socket of the MAC contaminated with electrolyte.
I replaced C12 and the socket with new ones, cleaned the area arround the MAC and C12 using brush and isopropyl.
I also cleaned the PCB around the input connectors with IPA, because the former owner of the DMM resoldered all the input bushings and left some flux residue.

Result: same as before...
I also checked power supply voltage +5.2V, -5.1V, 3.15V, bandgap 1.24V - looking good so far.

[lowimpedance]

Just a thought, what about the MAC chip itself needing a IPA clean if its original socket was contaminated!. (you did IPA the area where the leaking cap was too ?).

[e-doc]

what about the MAC chip itself needing a IPA clean if its original socket was contaminated!

The gold plated pins looked OK, no visable contamination at the MAC at all.
Only one contact spring of the socket was colored darker than the remaining ones.
Maybe I should bath the MAC completely (?). I just don't want to take it out of the socket, because it was tight to insert the gold plated precision socket.

(you did IPA the area where the leaking cap was too ?).

Of course. I found some green "copper rust" at the PCB under the leaked cap.
After removing the dirt mechanically and by IPA, I resoldered the PCB tracks around the spot to remake their tin-coating. Then I IPA-brushed the whole area (MAC and C12) again.
After replacing the socket and C12 I IPA-brushed it twice.

[krivx]

My 8060A's MAC needed a couple of IPA soak-and-drying runs before the residual readings decreased to zero.

[e-doc]

Can I sink the whole PCB (including switches and buzzer) in IPA without damage?
What about the grease on the switch contacts?
I can use an ultrasonic bath too.

[e-doc]

I renewed another electrotylic cap (10uF / 16V / C21, not leaked but only remaining 3uF), removed the MAC from the socket and washed it in IPA.
I think, it ist much better now, but the problem is not completely solved (-> 2VAC range).

Code: [Select]

range     offset
200mVDC  -0.01 to 0.00
2VDC     -0.0001 to 0.0000
20VDC    -0.001 to 0.000
200VDC   -0.01 to 0.00
1000VDC  -0.1 to 0.0

200mVAC   0.00
2VAC      0.0030 to 0.0045, depending on mechanical tension on the input bushings? (not really reproducable)
20VAC     0.000 to 0.001
200VAC    0.01
1000VAC   0.0

200Ohm    0.00
2kOhm    -0.0001 to 0.0000
20kOhm   -0.001 to 0.000
200kOhm  -0.01 to 0.00
MOhm     -0.0001 to 0.0000


Trying to clean the 2V and 20V range switches (S5, S6) by IPA did not help anyway.

In the end cleaning of the insulation inside the case bottom solved the problem perfectly (I thought, see PS below...).

See manual chapter 5-7:

                        Caution
Do not touch or contaminate the plastic insulator that is attached to the inside of the case bottom.
When the instrument is assembled the insulator makes contact with the leads on the bottom of the main pcb.
Contaminants could cause undesirable conduction paths.
If the insulator becomes contaminated, clean with isopropyl alcohol.

BTW: What an excellent "instruction manual" http://assets.fluke.com/manuals/8060a___imeng0300.pdf.
IMHO better than most of todays "service manuals"...

PS:
The failure came back this morning  (never ending story?).   

Up to 150 digits offset in the 2VAC range on shorted input.
The display changes on pressing the case top and back together or slightly pressing the range buttons up or down (in front or back direction).

In the end (?) cleaning of the area inside the plastic case around the input bushings solved the problem (let's see how long...).
 

[Johnny2Bad]

To Dr Taylor:

Naturally I found this thread extremely interesting reading, and I don't own an old Fluke multimeter (same as many others, couldn't afford one, but now own an 87-V).

In any case, I was intrigued by your early posts whereby you noted that you designed the 8060 specifically with features useful for someone interested in using the meter with audio measurements in mind, and that you did this because of your own interest in audio circa late 70's / early 80's.

while acknowledging that it's clearly off-topic, I was wondering if we could coax you to elaborate a bit on your interest in audio at the time you were crafting the unit that would eventually become the production 8060 series meters?

I promise to respect the thread (and hope others will as well) and keep the off-topic commentary to the minimum (by that I mean after this post, to zero), but would love to read one post from you on the subject.

[BMack]

Great thread, loved reading through it. I did have a question I was going to start a thread over but it seems more fitting here, so thanks for the recent BUMP. I found a Fluke D 800 recently and was curious how old it was, I can't even come up with a good guess. I don't know what I'd do with it but for some reason I'm drawn to buy it.

This is not the same meter and not my pic but it's a pic of the same model.

[retiredcaps]

I found a Fluke D 800 recently and was curious how old it was, I can't even come up with a good guess.

Likely 1980 as per

http://www.eham.net/ehamforum/smf/index.php?topic=71868.0;wap2

Chuck at Fluke talks about the D800 at

http://www.fluke.com/fluke/sgen/community/fluke-news-plus/articlecategories/rd/chuck-checks-out-forums-on-test-equipment

[macboy]

I know this thread is talking mainly about old Fluke handhelds, but I recently acquired a nice old bench meter, a Fluke 8505A. I don't know the exact manufacture date, but the first printing of the manual goes back to 1983 (33 years ago). This is a 6.5/7.5 digit meter (only 10 VDC range can do 7.5 digit) that is a full width, 3U height rack-mount beast that is as deep as it is wide and weighs just short of a metric-holy-crap-tonne. It uses what Fluke described as "Recirculating Remainder A/D Conversion" or "R² A/D". That's essentially a 5-bit + sign SAR ADC (five bits!), from which the remainder (error) is sampled, amplified, and fed back for conversion a total of 4 times (in addition to the original conversion of the input itself). The result is a 24 bit (23+sign) conversion. The instrument does >500 of these 24 bit samples/second, and to obtain a noise-free 7th digit, you need to set up each reading to average 128 or more samples, which gives you no more than a couple readings per second. Mine has the Ohms, AC RMS, and GPIB options (yes only DC volts is standard) but is missing the current shunt option that was originally installed. Still a bargain at 100 Canadian pesos (~$75 USD). The manual is typical for 80's era test equipment, having 315 glorious pages full of operating and service info including detailed theory of operation, block diagrams, exploded views, PCB component placement, parts lists, troubleshooting guides, and all-important complete schematics.

If interested, the description of the R² A/D Converter starts on page 87 (of 315) in the manual downloadable from Fluke (8.3 MB).

I'll try to get a pic up later today.

[BMack]

I found a Fluke D 800 recently and was curious how old it was, I can't even come up with a good guess.

Likely 1980 as per

http://www.eham.net/ehamforum/smf/index.php?topic=71868.0;wap2

Chuck at Fluke talks about the D800 at

http://www.fluke.com/fluke/sgen/community/fluke-news-plus/articlecategories/rd/chuck-checks-out-forums-on-test-equipment

You are one of the most helpful people I've ever come across on any forum, you are great at finding info and finding helpful links. Thank you for this and the other thread 

[Robomeds]

I found a Fluke D 800 recently and was curious how old it was, I can't even come up with a good guess.

Likely 1980 as per

http://www.eham.net/ehamforum/smf/index.php?topic=71868.0;wap2

Chuck at Fluke talks about the D800 at

http://www.fluke.com/fluke/sgen/community/fluke-news-plus/articlecategories/rd/chuck-checks-out-forums-on-test-equipment

You are one of the most helpful people I've ever come across on any forum, you are great at finding info and finding helpful links. Thank you for this and the other thread 

Second the above!

[drdanke]

Thought I would share some pictures of my new "old" meter..  I purchased it from a local estate sale for $5.  Fluke 8060A in unused condition.  Absolutely mint in box with case.  So far, I put a fresh battery in it, and tested all functions, and everything is spot on.  It's really surprising how accurate these can be after all of these years.  I haven't opened it up yet to check the caps, but with it working perfect, I will probably wait a bit until I replace them.  I was going to sell it and use the funds to buy a brand new meter... because "newer" is ALWAYS better, right?  Then I found this thread, and found out how good of a meter this really is.  Needless to say, I've fallen in love with it, and really feel bad I even had a thought of selling it to buy something "newer"...  Enjoy the pictures!

[retiredcaps]

I purchased it from a local estate sale for $5.  Fluke 8060A in unused condition.  Absolutely mint in box with case.

Awesome deal. 

I haven't opened it up yet to check the caps, but with it working perfect, I will probably wait a bit until I replace them.

While the outside is in mint condition, I wouldn't assume the insides are the same.  I urge you to take it out and closely examine the bottom of the capacitors which is where they leak in these 8060As.  They could have already leaked if the meter was stored in a hot environment (attic with window, sunny year round weather, 45+C in Arizona, etc).

[pascal_sweden]

They don't make such beautiful multimeters anymore! You are very lucky!
I am going to look out for this model as well from now on!

[ModemHead]

I purchased it from a local estate sale for $5.  Fluke 8060A in unused condition.  Absolutely mint in box with case.

I hate you. 

Judging by the condition of the box, carrying case, and the fact that the probes are newer style, this one is probably one of the last sold, which was well into the 90s.  The caps may very well be just fine, but an inspection wouldn't hurt.

Enjoy!

[lowimpedance]

Soo shiny, what a beauty..... almost to good to use  .
Lucky bugga enjoy.

Seriously though as has been suggested do check those caps, would be a crying shame to have such a minty outside with a ruined inside.

[Enigma-man]

I have an 8500A with only the voltage option.  Last year, around this time, I put in an AC filter module because RFI made it unusable.
If I turned on my Brunelle function generator, the Fluke went crazy.  Solved that problem after the filter was added.
After a period of time, totally random, the display would go blank. Turning the power off and on restored operation. Sometimes
it would work for minutes other times I could leave it on for days without a problem.
My controller had 2708 eproms on it and they drew a lot of power.  The eprom PCB was burned where the regulator was soldered to the board.
There was no heatsink and no room for one either.  The regulator was temporarily mounted on the side chassis to act as a heatsink.
I began to have fears of the 2708's losing their data or one failing.  I had enough unused ones to reprogram, but no 2708 programmer.
There was an Apparat programmer that I had from my old TRS-80 Model III and Model 4.  I tried firing up a Model III but the diskettes were
probably NFG or maybe the disk drive was at fault. Needless to say, wasted time and going back to TRS-DOS wasn't going to happen.
All that knowledge went out of my head as I needed to make room for PC related stuff and later the insidious and vile Windows 95.
I remembered that I had converted a Rad Shack CoCo 1 as an eprom programmer in the late 80's.  Apparently, I was smart enough to have a sticker
that read "exec 49152" still attached.  All I needed was a monitor to hook up to it.  No CGA/EGA/VGA was going to cut it.  It was composite video.
At this point I should have found a DeLorean, Marty McFly and the Doc to go back to 1988 when all this old sh*t worked and I knew what to do with it...
I managed to find an old Panasonic 9 inch (22.86 cm for us metric guys).  It worked and I was ready to read and program some 2708's.
Then I had a brilliant idea. Scrap the 2708's and put in 2716 or 2732 single 5 volt units.  Modifying the PC board was a piece of cake and within
hours I was reading in the 2708's and programming the replacement 2732's.  I didn't have enough 2716's.  It took time to erase the 2732's and some were
faulty, but in the end I was successful.  I plugged in the controller and turned on the power.  It worked.
The 8500A still has a problem.   So far I have replaced some cmos and 74LS series chips and even the 8080A CPU with no success.
This problem was present before I did the eprom modification so I know it isn't that.  Without other boards to plug in, I'll have to live with it until another comes along.
I saw on either the first or second page an 8500A had its controller die and the owner parted with it.  I think that was a few years before I got mine so if I was a member
here I would have shaken my head and said "Too bad for the 8500A" and moved to the next posting in the thread.
Anyway, the 8500A 2708's are in an antistatic tube in case someone out there may need one.
 

[Excavatoree]

Awesome find, drdanke.   I'll be a third voice  urging  you to take Retiredcaps' advice.  I thought "these are fine I don't see any leakage"  but I removed the capacitors as his insistence.   I'm glad I did.    The board damage occurs below the capacitor and is almost impossible to see.   

Yours is so nice, I'd have for you to not catch a problem when it's easy to fix. 

[retiredcaps]

@Excavatoree

You and your Fluke staircase photo got a shoutout on Dave's eevcomment #1



I can't find the exact time index right now for it.

[Gromit]

What a great post.  I have used Fluke meters for a long time, but my personal meters are a Fluke D804 and an 89IV.  I recently dug a Fluke 8808A out of the recycle bin at work to see if I could repair it, but it has serious issues which is likely why it was there to begin with.  I have tried to find schematics (I know, unlikely) to no avail and troubleshooting without them is not a simple task.     If anyone has advice, opinions etc. I'm listening.

I bought my Fluke D804 back in 1981 or 1982, then, I think, a year or so later Fluke quit selling that meter, at least it seemed that way to me.  Does anyone know How the D804 compared to the other Fluke's at that time?  Was it a short lived meter?  A Google search located a PDF of Popular Electronics Sept. 1981 with an add for the Fluke D804.  In the same issue was an add for 8" floppy disks and an article on the 8080A processor!!

Well, I still have my D804 in pristine condition with the original leads and I still use it when I need a second or third meter.  I also continue to use the B&K Model 177 VTVM I bought in the 70's when I worked at a TV repair shop when I was a kid to help finance my electronics hobby.  Yep, those were the days!

[drtaylor]

I occasionally get asked about replacement parts for 8060A's. I'm combining two queries I recently received here to help anybody in the same boat.

Question1:  In this thread, Findm-Keepm suggests that these SPH resistors
http://www.mouser.com/ds/2/414/SPH-SPF-461183.pdf
are equivalent to Fluke 8060A 1k ohm 2W fusible resistor."

DRT Answer: No, I don't think the SPH is a good choice to replace the 1K resistors. They are wire wound and the inductance could have an effect on the AC response. The original resistors were good old carbon composition. Terrible in every  way except they are extremely rugged in transient events. The original design did not really have fusible resistors, but carbon comps would always fail open...fusible sort of.

I now recommend the Ohmite OY series, PN OY102KE. These have the surge strength of Carbon Comp, but are constructed of more modern materials. They perform well in an 8060. These are in stock at Mouser. http://www.mouser.com/ProductDetail/Ohmite/OY102KE/?qs=%2fha2pyFaduiyQUi6McZj1pNmp3wbBKbDI%252b3Db0HwOiE%3d

Question2: "I am reviving a few 8060As, and I have a few failed JFETs(Q1).
The originals are Siliconix parts, and I am unable to find a datasheet.  Do you have any insight or info on what characteristics I should look for in a replacement?  Thank you for your time."

DRT Answer: These were low RDS N-Chan Jfets. They were similar to a J106, but selected for Vgs Cutoff of -3 to -4.5V. If you get a few J106 parts, you can select them to make sure they fully cut off when Vgs is no more than -4.5. These are also available at Mouser in the TO-92 package.  http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/J106/?qs=sGAEpiMZZMv4z0HnGdrLjpo3FY8YkyPvebpfrX4sUEw%3d

J107s would probably work without selecting for Vgs, but the on resistance is a little higher which will slightly shorten battery life. Regardless of which JFET you get, get them quick because TO-92 JFETs are a dying breed.

Question 3: "Please recommend replacement caps"

DRT: As far as those pesky aluminum electrolytics that spew destruction on the PCBs, I believe retiredcaps already covered this topic. I did spend the time a few years ago to select replacements, and will spend time again if I get asked.

And...last but not least... Yes, I still have a few autographed 8060 Original Manuals. If you showed up in the Seattle area, I'd gladly give you one. But I'm just too lazy to try to figure out how to post them out of country, and how I'd get reimbursed for postage (yeah I'm cheap too, the 8060 didn't make this boy rich).

[retiredcaps]

Modemhead has a new blog entry on the IBM 8060A.  It includes a digikey capacitor shopping list.

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

[Robomeds]

Glad to see a new entry on Mr Modemhead's blog! 

[saturation]

Does anyone know how to decode the serial numbers on the Fluke DMMs?  Are they the same even to the modern ones?

Worse ase, I can guestimate the manufacture date from the date codes on some of the ICs on the board for a ball park figure.  But the serial number should be the best bet.

I hope you all don't find this too much off topic.