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#650 Reply
Posted by
joeqsmith
on 14 Feb, 2019 12:35
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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.
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#651 Reply
Posted by
Dave Wise
on 14 Feb, 2019 22:25
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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.
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#652 Reply
Posted by
bitseeker
on 15 Feb, 2019 01:51
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Looks much better, Dave, and welcome.
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#653 Reply
Posted by
scopeman
on 14 Mar, 2019 01:29
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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
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#654 Reply
Posted by
bd139
on 14 Mar, 2019 13:36
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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.
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#655 Reply
Posted by
TubeDoc
on 22 Mar, 2019 16:00
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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.
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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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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
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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?
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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
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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
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#662 Reply
Posted by
GregDunn
on 18 May, 2019 11:56
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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.
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#663 Reply
Posted by
bob91343
on 18 May, 2019 17:43
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Do you want to foist that 3478A on someone who might try to repair it? That would be a fun project for me.
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Sorry, it's a company asset, can't sell it!
JT
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#665 Reply
Posted by
elecdonia
on 26 May, 2019 18:18
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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.
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#666 Reply
Posted by
med6753
on 26 May, 2019 18:55
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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?
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#667 Reply
Posted by
GregDunn
on 26 May, 2019 19:12
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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.
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#668 Reply
Posted by
Pablitox
on 05 Jul, 2019 02:05
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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?
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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
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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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#671 Reply
Posted by
drtaylor
on 05 Jul, 2019 05:17
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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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#672 Reply
Posted by
Pablitox
on 05 Jul, 2019 05:43
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The image I used was of mrmodemhead. This is the plate of my multimeter. It is somewhat blurred. Sorry for my lousy English
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#673 Reply
Posted by
vinlove
on 05 Jul, 2019 05:48
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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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#674 Reply
Posted by
bd139
on 05 Jul, 2019 07:16
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Plus if you’re burgled it doubles as a melee weapon
