Author Topic: Fluke 8200A read problem.  (Read 7277 times)

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Offline neo

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Fluke 8200A read problem.
« on: September 23, 2017, 01:41:58 pm »
I have a Fluke 8200A which reads ohm's and volts perfectly and accurately. It turns on all the nixies work and there are no problems except for one small annoyance.
 
When i press one of the ohm's ranges a light turns on and i hear a faint click, for simplicity i will call this a "range latch", the ohm's range has no problems with range latching however of the three ranges for volts, DC, AC, MVDC; all ranges have iffy range latches.

That is to say sometimes it works, often enough that i could verify that it will read DC volts very accurately, but most of the time there is no light or click.

By deduction i assume this means it is relay related but, and this is where the point of this thread comes in, why is it all three ranges?
How would i fix it if it is a relay? I mean more specific than just soldering a new one in, for example identifying which one it is and a viable replacement.
To be honest i am somewhat intimidated by my lack of success on other things as of yet and i am slightly intimidated by the inner workings of this thing without a manual.

So in closing, does anybody have a manual or at the very least a schematic for this thing? I'd be happy with one drawn on the back of a napkin so long as it's legible.
I know i can buy one but i would prefer to save that for a last resort, please and thank you.
« Last Edit: September 23, 2017, 01:51:48 pm by neo »
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #1 on: September 23, 2017, 09:08:47 pm »
neo -

If I'm understanding this, when you change the meter's measurement mode, the resistance works all the time, but the other modes (DC, AC or mVDC) don't always activate properly, and when they don't the associated indicator light does NOT come on, correct?  Am I also correct in concluding that if the indicator comes on that the associated mode works correctly too?

In short, if the light comes on, the mode works, but the light (other than for resistance) doesn't always come on?

-Pat
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #2 on: September 23, 2017, 10:34:56 pm »
The signals traipse through the schematic like drunken sailors, but to begin with I'd suggest looking at the Ohms mode selector switch - as shown in the schematic below, there is a ground signal that goes through the series of mode switches, as traced by the pink line.  As the various modes are selected, the associated 'control' line is pulled low (control lines in green).  If I understand your description of the issue correctly, it seems that the problems are in the modes that lie beyond the 'Ohms' mode switch, so I'd begin by looking at the contacts at the top left of S4 on the schematic.



Good luck!!

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Offline neo

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Re: Fluke 8200A read problem.
« Reply #3 on: September 24, 2017, 02:52:16 am »
neo -

If I'm understanding this, when you change the meter's measurement mode, the resistance works all the time, but the other modes (DC, AC or mVDC) don't always activate properly, and when they don't the associated indicator light does NOT come on, correct?  Am I also correct in concluding that if the indicator comes on that the associated mode works correctly too?

In short, if the light comes on, the mode works, but the light (other than for resistance) doesn't always come on?

-Pat

Exactly. Thank you for the schematic, i'll look at it and update here.
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #4 on: September 24, 2017, 03:04:12 am »
Small question , how do i get at the switches? Short of complete disassembly that is.
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #5 on: September 24, 2017, 03:31:29 am »
To answer my own question, no it is not. Completely disassembly IS required to get to switches, now that i have their board loose what should i do now?
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #6 on: September 24, 2017, 03:57:20 am »
I'd shoot some contact cleaner into the switches and exercise 'em (ohms especially).  If the meter was used in a test setup and left in 'Ohms' forever, the contacts on that switch may have oxidized; perhaps repair would be as easy as cleaning them.

If you have access to the bottom of the board, trace the circuit and try to see which sets of contacts are the ones in question, and check their resistance with the switches in each position.  I'm guessing that they will be one of the pairs at the rear of the switch body (furthest from the button), but cannot be 100% certain of this.

-Pat
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #7 on: September 24, 2017, 04:39:38 am »
I'd shoot some contact cleaner into the switches and exercise 'em (ohms especially).  If the meter was used in a test setup and left in 'Ohms' forever, the contacts on that switch may have oxidized; perhaps repair would be as easy as cleaning them.

If you have access to the bottom of the board, trace the circuit and try to see which sets of contacts are the ones in question, and check their resistance with the switches in each position.  I'm guessing that they will be one of the pairs at the rear of the switch body (furthest from the button), but cannot be 100% certain of this.

-Pat

I don't have any contact cleaner as of yet, unfortunately.

http://www.ebay.com/itm/11-Oz-Premium-Electronic-Contact-Cleaner-Spray-The-Best-Quick-Drying-Specialist-/263212323991?epid=1325135137&hash=item3d48ad5497:g:N~0AAOSwsm1ZviWe

Would that work or is it "deoxit or nothing" when it comes to this?

Anyways, i will try to sort out which pin is which. I notice that the AC button does not seem to want to stay depressed.
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #8 on: September 24, 2017, 05:03:55 am »
The ac button will stay depressed if pushed hard enough.
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #9 on: September 24, 2017, 05:08:14 am »
I think the CRC stuff is geared more towards electrical contacts in vehicles, but it's worth a shot.  I doubt it would hurt anything.  Contact cleaner was much more readily available back in the days of mechanical TV tuners, but those days are long gone.  The Caig stuff seems to be the gold standard these days, but I believe the company that makes WD-40 also has a contact cleaner out, and I seem to recall hearing good things about it.  FWIW.

The AC button not latching is likely an issue with gummed up lube on the moveable bar that latches and releases the buttons.  The contact cleaner will probably help that, too, by cleaning away the sticky, dried out grease.

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #10 on: September 24, 2017, 05:22:55 am »
The wd-40 contact cleaner isn't all that more expensive so i will go with that, thank you for mentioning it.
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #11 on: September 24, 2017, 05:46:36 am »
 :-+ :-+

-Pat
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #12 on: September 24, 2017, 06:39:38 am »
Mapping switches now, also someone has been in this before i had suspicions that were confirmed by a nixie that did not match the others. Same nixie just a few years off, the glass is all that is different. It doesn't appear they did anything else and did well soldering it in, but still something to keep in mind.
« Last Edit: September 24, 2017, 10:23:11 am by neo »
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #13 on: September 24, 2017, 09:11:40 am »
OK this is the way the continuity on the switches worked out
30 connects directly to  M \$\Omega\$ 3 and 4, K \$\Omega\$ 9 and 11,  \$\Omega\$ 9 and 10, VAC 9 and 4, MV 1 and 4

M Toggled, 1 and 2; Not toggled, 5 and 6.
K Toggled, 2, 4 and 7; Not toggled = nothing.
O Toggled, 2, 4 and 8; Not toggled 3 and 5
VAC Toggled, 7 and 2; Not toggled, 11 and 6.
M-V Toggled, 2, 3, 8 and 10; Not toggled 64 ohms between 1 and 3, 3 and 5 connected, 6 connected to 1

DC switch is weird, not toggled 3 and 5 have a direct path to ground but 4, 6, 8,  10 and twelve all have a 64 ohm resistor to ground. 4 and 6 are connected. toggled 3 and 1 have a direct path to ground and the only change in the other pins is that 4 is no longer connected.

01  02
03  04
05  06
07  08
09  10
11  12
the orientation for the switches, nixies upside down and facing me


I checked it with two multimeters, three times each so i am relatively sure that what i listed is correct to my unit.
« Last Edit: September 24, 2017, 09:18:07 am by neo »
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #14 on: September 25, 2017, 05:25:13 am »
I have now also checked each pin of both MV and VDC and i cannot find any that connect to what is labeled as their corresponding control pin, 26 for MV and 25 for VDC.
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #15 on: September 25, 2017, 07:45:31 am »
I'll try to pop the cover off of mine tomorrow after work and see if I can take some readings for comparison.

-Pat
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #16 on: September 27, 2017, 12:55:02 am »
OK so as to provide an abridged version of my work on it.

Didn't work, sprayed contact cleaner on switches and then it didn't work because boards were loose.

Fixed the loose board and now works, VAC up to at least 10V, VDC up to at least 230V.
OHM's works up to a little above 100k before it loses its mind.

NOTE, the only reason i stopped voltage tests there was that it was the highest voltage i could safely generate.

Switches felt fine before reassembling it, but a few hours after the contact cleaner they are gummy and hard to push again.

Took front off and contact cleanered again and it feels fine now.

Ohms works above 100k now, however anything above 100K swings the reading alot.

300K reads as 285K-336K
1M reads as 900K-1087M
and 10M swings the widest between 8M-12M
« Last Edit: September 28, 2017, 09:35:31 pm by neo »
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #17 on: September 28, 2017, 09:38:45 pm »
All in all i think it is currently working well enough to call it good, unless someone has something to say about the  \$\Omega\$ reading swinging.

EDIT:
See below.
« Last Edit: September 29, 2017, 12:51:45 am by neo »
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #18 on: September 29, 2017, 12:21:40 am »
This thing is going to drive me up a wall.

The contact cleaner once applied makes the switches easy to work, however a few hours later they are an unuseable gummy mess. As if that wasn't enough it only selectively works, AC works in testing but not later for example.

EDIT:
These switches are seriously screwy i think, if the contact cleaner is fresh it works great if not it gets screwy.
For example the ranges don't all work even though they all did before, or the buttons become inoperable.
« Last Edit: September 29, 2017, 12:45:58 am by neo »
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #19 on: September 29, 2017, 01:31:09 am »
Crap.  I've been pulled away to help a friend with painting every night, so I haven't been able to open mine.  From the sound of it, it's a switching issue, and somehow the contact cleaner is incompatible with the grease in the switches.  What did you wind up using, the WD-40 stuff?

Have you thoroughly flushed them with it, and did crud come out, or did you just give them a little squirt?

I just grabbed mine; I'm pulling the bottom cover now.  (Have to poke a hole in the August 1987 cal sticker to do so. :'( )

-Pat
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #20 on: September 29, 2017, 02:36:32 am »
I sprayed it, worked the switches, sprayed a little more and then worked the switches a little more. Yes, the WD-40 contact cleaner is what i am using and i have yet to see crud but i also have not investigated the switches recently as that requires full dismantle.

Shame about the cal sticker, thanks a lot for your help though.

Just out of curiosity what year is yours? Mine was assembled august 1971, at least thats what the ink stamp on the chassis says.
« Last Edit: September 29, 2017, 02:42:23 am by neo »
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #21 on: September 29, 2017, 02:53:16 am »
I think i may be able to fix the switches by bathing them in contact cleaner and working them until my fingers don't work. Maybe, i think it might be getting better because,at least currently, everything works including the switches. Time will tell.
« Last Edit: September 29, 2017, 03:06:29 am by neo »
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Offline bitseeker

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Re: Fluke 8200A read problem.
« Reply #22 on: September 29, 2017, 04:46:58 am »
It sounds like you're starting to scratch the surface, as it were, on the contacts in the switches. When the cleaner evaporates, the goo settles and causes problems. If the cleaner can't dissolve the muck and nothing will come out of the switches, it may not improve without disassembly or replacement of the switches. Perhaps, as Pat implied, a different cleaner may work better to dissolve the old lubricant.
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #23 on: September 29, 2017, 06:35:53 am »
This beast will certainly not win any 'ease-of-serviceability' awards, at least not for the mode and range switches.  It seems that they start with those and then build the rest of the meter around them.   :wtf:

Here is the chassis with the outer and inner top and bottom covers removed (four screws and one screw each, respectively), and the front panel (four additional screws after top and bottom outer covers are removed) disconnected and taken off.  I left the boards that were hooked to the input jacks (four of them) connected and removed them as a unit.  The black and white leads visible at front left are the rear analog input connections; they too connect to the front panel jacks but as the cable is fixed to the chassis, I disconnected them to remove the panel:


Boards and front panel:

Left to right: AC Converter, input buffer, ohms converter, and millivolt converter PCBs.

Here is the display/interconnect board assembly removed from the meter chassis (four screws in the bulkhead, and two more at the rear adjacent to the edge connectors, along with two wires to the power switch:
Front oblique:


Rear oblique:

Note that the display board is directly above the switches, supported on standoffs that also hold the bulkhead with the card guides on it.  To make matters more difficult, they do not appear to be easily separated - in the 'front' photo, note the long, low grey connector visible just behind the two rightmost nixies and the small daughter board with the trim pot on it.  Its opposite end can be seen in the 'rear' view just below the card guide bulkhead, beneath the guides second and third from the left.  This is the ribbon cable that ties the display board to the interconnect board.  On my meter, at least, it is about 4-5" long, and those are IDC connectors that are soldered to each of the boards.  The display can be removed, but it will remain attached and flopping around.   :palm:  I suppose for easier access to the switches, the standoff screws could be removed and the now loose display assembly moved over the edge connectors and laid on its back, then affixed to the two rear mounting points with small two hole brackets and the screws that previously held it to the chassis...


Closeups of the switches causing neo grief are below - the mode switches that are giving him trouble are soldered to PC boards both above and below.  They solder to the interconnect board on the bottom, then have a small board with the mode indicators soldered to the top.  NOT easy to clean, alas.   |O :




I'll see if I can further disassemble things tomorrow, and get some more photos up.  Other photos of the meter are at: https://pmanning.smugmug.com/Electronics/Fluke-8200A-Digital-Voltmeter

-Pat

« Last Edit: September 29, 2017, 06:53:45 am by Cubdriver »
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #24 on: September 29, 2017, 06:41:44 am »
Oh, and neo, mine is a baby compared to yours.  I haven't found a date stamp anywhere on the chassis, but the component date codes range from the late 70s to mid 1980, so I'd assume that it was made late in 1980.  I'm curious - does yours use LEDs for the mode indicator lights, or incandescents, or...?

-Pat

Wait - belay that previous date estimate - a closer look at the ohms converter board reveals trim pots with 1981 production dates (light blue ones on the right), (and a big honkin' 6.99M precision resistor with a mid '79 date - Fluke must have bought things in big lots!), so I now guess mid 1981 for a build date?

« Last Edit: September 29, 2017, 06:47:34 am by Cubdriver »
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #25 on: September 29, 2017, 11:52:48 am »
Oh, and neo, mine is a baby compared to yours.  I haven't found a date stamp anywhere on the chassis, but the component date codes range from the late 70s to mid 1980, so I'd assume that it was made late in 1980.  I'm curious - does yours use LEDs for the mode indicator lights, or incandescents, or...?

-Pat

Wait - belay that previous date estimate - a closer look at the ohms converter board reveals trim pots with 1981 production dates (light blue ones on the right), (and a big honkin' 6.99M precision resistor with a mid '79 date - Fluke must have bought things in big lots!), so I now guess mid 1981 for a build date?



Near as i can tell its all neon or regular incandescents, so then i take it i got an old one and that explains the switches.
I had my hopes up last night an hour after spraying the switches but now in the morning they are back to being the same gummy mess.

EDIT:
Once in a range it is fine even after the contact cleaner dries its "dry switching"  that is the problem.
« Last Edit: September 29, 2017, 01:31:45 pm by neo »
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #26 on: September 29, 2017, 12:58:48 pm »
It sounds like you're starting to scratch the surface, as it were, on the contacts in the switches. When the cleaner evaporates, the goo settles and causes problems. If the cleaner can't dissolve the muck and nothing will come out of the switches, it may not improve without disassembly or replacement of the switches. Perhaps, as Pat implied, a different cleaner may work better to dissolve the old lubricant.

i'm open to suggestions on what i should use, though i should note 50 dollar bottles of chemicals are out of my current price range.

It is actually all of the range switches not just one or two now and the best way into any of them with contact cleaner is just to pop the front off and spray the springs.
« Last Edit: September 29, 2017, 06:55:47 pm by neo »
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Offline bitseeker

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Re: Fluke 8200A read problem.
« Reply #27 on: September 29, 2017, 11:53:54 pm »
Wonderful teardown photos, Pat! I was also appalled at seeing those switches soldered on both ends between PCBs. That's just evil! By the way, in the 8200A manual, is there any info on disassembling the switch modules?

neo, I'm not sure what's the best option since we don't know what kind of gunk is in there. On the 8100A, the switch shaft and contacts can be removed by sliding it out the rear of the switch module. I don't know if that's the case with the 8200A. If you can get the shaft out, then you can clean the contacts directly.

Update: The 8100A manual says to clean with alcohol. Then lubricate the switch contacts with a thin coat of Rykon 2EP grease (American Oil Co.) or equivalent. Most contact cleaners have alcohol in them, but you could also try to fill the switches with IPA (not beer) and work them if you can't remove the shaft and contacts.
« Last Edit: September 29, 2017, 11:59:23 pm by bitseeker »
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #28 on: September 30, 2017, 12:32:59 am »
So i guess it all comes down to whether or not the switches come apart without breaking the thing.

The way i see it is i have three options, either;
A) Leave it in DC or \$\Omega\$
B) Take the switches apart and clean them.
C) Bathe them in a lot of chemicals.

I would rather have it fully functional.
Pat, could you kindly look in the manual for information on this?
IPA = isopropyl correct?
« Last Edit: September 30, 2017, 12:35:16 am by neo »
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #29 on: September 30, 2017, 02:09:08 am »
IPA is isopropyl, yes.

I looked in the manual and there are instructions on the switches; I've taken photos and will post them as soon as I get a computer keyboard issue fixed.  Give me an hour or so...

-Pat
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Re: Fluke 8200A read problem.
« Reply #30 on: September 30, 2017, 03:40:24 am »
That's great news, Pat. I'm optimistic that the switches will be similar and be able to be disassembled without desoldering.
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #31 on: September 30, 2017, 04:53:02 am »
Ok, it took a bit longer than an hour to get the photos taken, marked up, uploaded, and captioned, but I'll have something posted showing my take on the procedure shortly.  (shortly being however long it takes me to type it up and insert the pics.)  Meanwhile, here are photos of what I was talking about last night regarding securing the display assembly to the interconnect board so that the ribbon cable doesn't get buggered up after dismounting it to gain access to the switches...

I wound up getting some of that evil plastic that everything is blister packed in these days - you know, that impossible to tear stuff that you can barely cut with bolt cutters and that will slice you open if given half a chance.  Anyway, I found a flat piece about 1.5 x 3", and folded it into a four layer accordian shape.  I burned a pair of holes through all four layers with a soldering iron (ahh, the smell brought back memories of melting holes in Rat Shack P-box kits back in the days of my misspent youth), then cut them in half to wind up with two folded plastic pieces with a pair of holes.

After first removing the five screws securing the display assembly and bulkhead to the interconnect board (two short in front, three longer across the back), I used the short screws from the front to secure the bulkhead to the outer pair of short rear standoffs on the display board.

The plastic pieces were then used to bridge the upper bulkhead holes to the rear brackets on the interconnect board, and hold them nicely secure relative to one another giving you one thing to work with, rather than two tied together with a potentially delicate ribbon cable.  The photos should explain what my rambling probably did not.   :P

Display/bulkhead removed from interconnect; bulkhead secured with front mounting screws to outer rear standoffs (I put the screws that held the bulkhead and interconnect board rear to the enclosure sides back into their respective holes when I disassembled the meter to help keep them organized and to reduce the chances that my furry lab assistants might decide to play with (AKA lose) the loose hardware.):


Detail of screw holding bulkhead to standoff:


Plastic 'brackets':


Detail of assembly with bracket in place:


Overall front oblique:


Overall rear oblique:


-Pat

If it jams, force it.  If it breaks, you needed a new one anyway...
 
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #32 on: September 30, 2017, 04:55:15 am »
That's great news, Pat. I'm optimistic that the switches will be similar and be able to be disassembled without desoldering.

Alas deslobbering will be necessary to service them.   |O

The good news is that the board that must come off is single sided without through hole plating, and there are only 14 connections to desolder.  The switches themselves can remain on the main interconnect board.

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #33 on: September 30, 2017, 06:30:02 am »
Ok, now for the fun one.  Fluke 8200A mode/function and/or range switch repair.  As bitseeker suggested, dismantling and cleaning the switches is pretty easy.  Easy like replacing the pilot bearing in a car with a manual transmission is easy.  Once you get there, it should be cake - the getting there part is the issue...   |O |O

To begin with, the meter must be torn down to the point that the display board/interconnect board assembly is out and in your hands, and from there the display board must be dismounted from the interconnect board, as it sits directly above the switch gangs.  I'd suggest securing them to one another somehow (such as the method using plastic tie straps as shown in my earlier post) to make handling them easier and reduce chances of damage due to movement between them.

Interconnect/display assembly with display board secured out of the way of ganged switches on interconnect board:




The RANGE switch (on the right) may be worked on at this point as it is accessible, however if the FUNCTION switch gang (Vdc, Vac, ohms, etc.) needs attention, then the additional step of removing the function indicator PCB atop these switches must also take place.  At a glance, this doesn't look like it should be too terribly difficult to do, as it is a single sided board (no through hole plating to worry about) and there are only 14 connections to deal with.  A solder sucker and/or solder wick should permit removal to be accomplished with a minimum of foul language and hair loss.

Function indicator daughter card.  Desolder switch connections (in rows, front to back - do not desolder indicators or resistors).  Older versions will likely look at least somewhat different as they may be incandescent (most likely) or neon, rather than LEDs.  Regardless, removal should be the same:




Once access to the switches has been obtained, the rear support bar must be removed from whichever gang of switches is to be repaired.  The support bar is a three sided aluminum channel that is affixed to the switches by a combination of 'L' shaped slots that engage posts on the switch bodies and retaining tabs that are bent inwards and bear against the switch body sides, preventing the bar from shifting laterally and disengaging from the posts:

Front and rear support bars (range switches shown here):


Support bar and switch parts (range switch):


This image of the range switch as an error in the markup; the small top left tab is NOT a locking tab - they are on the bottom of the rear bar on the range switch:


Support bar on function switch assembly:



First off, prior to removing the support bar, ALL of the switches in the gang must be in the off (out) position, as when they are on, the rear of the actuator extends out through the support bar.  Pushing a different switch in far enough to release the 'on' one, but not far enough to latch it will accomplish this.

The rear support bar is removed by carefully bending the locking tabs flat with the face of the bar so that they will clear the switch bodies (there are multiple locking tabs, likely one between each switch).  On the range switch assembly, they are on the bottom, closest to the interconnect board, and on the function switch assembly they are on the top.  Once the tabs are bent flat, the support bar is slid in the appropriate direction (towards the outside of the unit, to the right for the range switch and to the left for the function switch) far enough to permit the retaining posts to disengage from the 'L' slots that they are in.  It is then removed by pushing it to the rear.  I have not taken a meter apart this far, so I cannot comment on the force needed to move and remove the support bar, but would not be surprised if gently prying with a screwdriver in one of the slots is needed.  If the bar is reluctant to move, recheck to ensure that all the tabs are bent clear of the switch sides.



Beyond this, the procedure shown in the following manual page photos should be followed to disassemble and clean the switches, and then reassemble everything.  The gist of it is that once the rear support bar is off, the buttons, retaining clips, and springs are removed, then the actuator and contacts may be pushed out through the rear of the housing.  The contacts are cleaned and the mechanism relubricated, then the whole mess goes back together.  I have no idea what a modern equivalent to their suggested grease might be, but I would use a small amount of white lithium grease if I were doing it.  Key being small amount, not a huge glob.



First page -
Sections 4-20, 21, 22, and 23 apply to ALL switches in the unit.  Note that section 4-24 applies only to the 'function' switches (for extra confusion, there are two sets of 'function' switches) on the small daughter board that has the AC mains switch on it.  These are push on - push off switches, NOT the ganged switches used in the 'function' and range assemblies we're interested in here.




Second page -
Figure 4-2 applies to the push on push off switches, NOT the ones we're interested in.  I believe that 4-3 shows something similar ot what our switches will look like internally, but am not 100% certain.  Our part starts at section 4-25:




Third page -
Now we're getting into the meat of the procedure.  the illustrations combined with the picures above should hopefully make the procedure clear:




Fourth page -
Hopefully section 4-26 or 27 will not be necessary, especially as I've no idea where one might find a replacement switch...:




Fifth page -
The remaining instructions on installing a replacement switch:
\]


And as always, assembly is the reverse of disassembly.

Hopefully this helps - good luck with it, and let me know if I can try to dig anything else out to assist.

-Pat

<edit to add note about ensuring all switches are 'off' before attempting to remove rear support bar>
« Last Edit: September 30, 2017, 05:49:49 pm by Cubdriver »
If it jams, force it.  If it breaks, you needed a new one anyway...
 
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #34 on: September 30, 2017, 02:43:03 pm »
https://www.amazon.com/WD-40-Specialist-White-Lithium-Grease/dp/B0083V8KBE/ref=sr_1_10?ie=UTF8&qid=1506780343&sr=8-10&keywords=white+lithium+grease

Would that be a good choice for the lithium grease?

Great  pictures and instructions, armed with those i might be able to manage disassembly and reassembly of the switches.
My board looks exactly the same only with little incandescent glass bulbs as opposed to red LEDs, in my opinion the white light is more fitting than the red.
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Offline Le_Bassiste

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Re: Fluke 8200A read problem.
« Reply #35 on: September 30, 2017, 03:25:27 pm »
can't comment on that lubricant, really.
 you want to avoid any mineral stuff, because it might deteriorate the pushrod and may have undesired creeping behavior. others may have better recommendations than i have here. i've been using white teflon grease, extremely sparingly applied to avoid any contact with the contactor elements to avoid creepage paths. see picture of dismantled keithley 200x input selector prior to cleaning, for the fun of it.
re-assembly went really smooth, and instrument passed keithley calibration lab without problems.
mind your carpet monster, though.
 

Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #36 on: September 30, 2017, 05:35:46 pm »
If it jams, force it.  If it breaks, you needed a new one anyway...
 
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Offline bitseeker

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Re: Fluke 8200A read problem.
« Reply #37 on: September 30, 2017, 06:46:10 pm »
Pat, nice job on the modern switch disassembly docs and the custom servicing brackets. It does appear that, apart from the number and location of switches, the 8100A and 8200A switches are essentially the same.

Fortunately, Fluke didn't solder every pin of the switches to that upper PCB. What a relief!
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #38 on: September 30, 2017, 08:39:03 pm »
Pat, nice job on the modern switch disassembly docs and the custom servicing brackets. It does appear that, apart from the number and location of switches, the 8100A and 8200A switches are essentially the same.

Fortunately, Fluke didn't solder every pin of the switches to that upper PCB. What a relief!

Thanks!  I suppose it's not surprising that they'd try to use common parts when possible.  They are certainly a PITA to service, though, thanks to their location.

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Offline bitseeker

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Re: Fluke 8200A read problem.
« Reply #39 on: September 30, 2017, 10:42:06 pm »
Yeah, I guess they're close enough in age to be able to share parts. I was afraid that the switches might be newer and, hence, less serviceable.
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Offline neo

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Offline Cubdriver

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Offline neo

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Re: Fluke 8200A read problem.
« Reply #42 on: October 01, 2017, 02:29:30 am »
I'm having a hard time disassembling the switches, i got the rear clip off as well as the button and spring but i have no clue how to get the shaft out.

EDIT: I got one.
« Last Edit: October 01, 2017, 02:36:41 am by neo »
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Offline bitseeker

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Re: Fluke 8200A read problem.
« Reply #43 on: October 01, 2017, 02:35:09 am »
Some of the switches have a front bar that is part of the mechanism that causes only one switch at a time to be engaged. You'll have to disengage the shaft from that front bar in order to get the shaft to come out of the back of the switch housing.
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #44 on: October 01, 2017, 02:41:52 am »
What does it mean if they are actually clean inside?

and what would i look up to buy a new key? Not a shaft just the little square key you push one of mine is slightly melty.
« Last Edit: October 01, 2017, 02:46:59 am by neo »
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Offline bitseeker

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Re: Fluke 8200A read problem.
« Reply #45 on: October 01, 2017, 02:51:33 am »
It doesn't matter much what it looks like. Start with the switch that exhibited the worst connectivity. Clean the contacts and reassemble the switch. Did it fix the continuity of the switch? If not, compare the metal contacts of that switch with the switch that works fine. Is the badly behaving one misshapen or have visible damage to the contact surface? Does swapping the metal contacts move the problem from the bad switch to the good one?

If the metal contacts of the bad switch are bent (more compressed than in the good switch), then they're bad. The manual says not to bend them back (i.e., replace the switch).
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #46 on: October 01, 2017, 02:53:43 am »
It doesn't matter much what it looks like. Start with the switch that exhibited the worst connectivity. Clean the contacts and reassemble the switch. Did it fix the continuity of the switch? If not, compare the metal contacts of that switch with the switch that works fine. Is the badly behaving one misshapen or have visible damage to the contact surface? Does swapping the metal contacts move the problem from the bad switch to the good one?

If the metal contacts of the bad switch are bent (more compressed than in the good switch), then they're bad. The manual says not to bend them back (i.e., replace the switch).

The only real way to test these is reassembly, continuity testing each one is a bit of a circus.
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Offline bitseeker

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Re: Fluke 8200A read problem.
« Reply #47 on: October 01, 2017, 02:55:19 am »
and what would i look up to buy a new key? Not a shaft just the little square key you push one of mine is slightly melty.

I doubt that you'd be able to buy just the keycap unless you can find someone who happens to have a stash of parts. Usually with old equipment, donor units are acquired to replace parts. The manual would have the part number, which you can then search for. Sometimes you'll get lucky and hit a site for vintage test equipment that has it.
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #48 on: October 01, 2017, 02:59:46 am »
I may have a small problem, one of the springs went flying and it flew right into obscurity. I was trying to be careful and i managed to get 5/6 but the 6th, as i said, went ping.

I really feel kinda dumb right about now.

EDIT:
The 6th shaft won't come out due to board standoff.
« Last Edit: October 01, 2017, 03:32:07 am by neo »
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Re: Fluke 8200A read problem.
« Reply #49 on: October 01, 2017, 03:35:44 am »
Uh, oh. Keep the pets, if any, away until it's found.
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #50 on: October 01, 2017, 03:40:59 am »
The real problem is i have too many pets and way too much stuff.
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #51 on: October 01, 2017, 04:04:26 am »
 :palm: I'm useless, i already screwed up. I tried to align contacts like the manual said, went to gingerly  push it in and bent two of them. Why am i doing this, it's about what it would be like if a giant tried to play with regular sized things.
« Last Edit: October 01, 2017, 01:40:58 pm by neo »
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #52 on: October 01, 2017, 04:26:58 am »
In an effort to be entirely fair i will say this, i have issues and do not take failure well. Therefore i apologize if i seem, rude, crass, demeaning or otherwise annoying.


I got one reassembled but it does not latch.
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #53 on: October 01, 2017, 05:01:44 am »
Two reassembled, neither latches.

When i took apart these switches i think i did something i can't fix.
I seem to have wrecked a set of switches on a fluke 8200A, i definitely wrecked at least one. 
 |O |O |O |O
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Offline bitseeker

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Re: Fluke 8200A read problem.
« Reply #54 on: October 01, 2017, 06:22:28 am »
Not every purchase is a score and not every repair is a success. The experience you gain is invaluable for the next one. All is not lost, though, because either this one can be a parts donor to the next or vice versa. Keep going and as many switches as you can restore will be one more success (and a spare part for future use).

Working on vintage gear is not taught in school, only the school of hard knocks, also known as on the job training. Onward to the next lesson...
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #55 on: October 01, 2017, 07:32:46 am »
The trick now will be to do some research and try to find what else uses those switches - perhaps something less desirable that can be purchased for a song and parted out to get replacements.  I'm headed for the sack now, but will try to do some searching over the next few days.  All may not yet be lost.

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Offline neo

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Re: Fluke 8200A read problem.
« Reply #56 on: October 01, 2017, 01:33:03 pm »
One thing i have learned, never take apart switches because, being the clumsy oaf i am, i cannot reassemble them
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #57 on: October 01, 2017, 01:40:24 pm »
Below i've included a figure of how i think the switches work, if i am right and i can find a switch that works like it i am more or less golden with a replacement.

| = common
V = normally closed contact
^ = normally open contact
- = non moving contact, read as the posts through the switches

-^ ^-
-| |-
-V V-
-^ ^-
-| |-
-V V-


So the question is, am i more or less correct?
« Last Edit: October 01, 2017, 01:42:37 pm by neo »
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #58 on: October 01, 2017, 02:35:57 pm »
Below i've included a figure of how i think the switches work, if i am right and i can find a switch that works like it i am more or less golden with a replacement.

| = common
V = normally closed contact
^ = normally open contact
- = non moving contact, read as the posts through the switches

-^ ^-
-| |-
-V V-
-^ ^-
-| |-
-V V-


So the question is, am i more or less correct?

Yes, that is exactly correct.  The second and fifth contacts from the front are the commons for each of the four switches in the individual housing.  Each is connected to the contact immediately in front of it when the switch is 'out', and is connected to the contact immediately behind it when the switch is pushed in.

-Pat
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #59 on: October 01, 2017, 02:48:22 pm »
This probably an absurd idea but i get this inclination to look to the fluke 8000A here, it can be had very cheaply in comparison and it uses the exact same keys so maybe....

conveniently i have one laying around i can probe for information so it ain't a complete crapshoot.
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #60 on: October 01, 2017, 03:22:08 pm »
It can't hurt to take a look.  I just downloaded an 8000A manual - it shows a different part number for the switch, but it's unclear in the 8200A manual whether the p/n shown is for a single switch or the entire assembly of them.   :-//  Physically looking if you have an 8000A at hand is your best bet.

-Pat
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Re: Fluke 8200A read problem.
« Reply #61 on: October 01, 2017, 03:42:27 pm »
Great news! The 8000A switches could serve as a replacement!

Not so great news, its either a gang of 8 or two gangs of 3 which would require two donors and either option has the spacing wrong, their more spread out on the 8200A
« Last Edit: October 01, 2017, 03:44:36 pm by neo »
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #62 on: October 01, 2017, 03:50:09 pm »
You should be able to swap the individual switches into the 8200A mounting rails as shown on the last two pages of the manual I posted pics of.

-Pat
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Re: Fluke 8200A read problem.
« Reply #63 on: October 01, 2017, 03:58:14 pm »
Wouldn't it cause problems with the bussing if they are not exactly the same size? Footprint is the same, soldering the lights on top might be a challenge because the posts are not exactly the same.

The biggest problem that leads me to question their ability to serve as drop ins is that the switch body itself is slightly different, nothing pokes out of the back when depressed.
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Re: Fluke 8200A read problem.
« Reply #64 on: October 01, 2017, 03:59:42 pm »
Could you provide me with an 8200A part number for the switches?

The way i see it i have three options,

A) Buy drop in replacements
B) Buy a broken 8000A and have someone better than me do the work on it to transfer contacts.
C) Buy a broken 8000A and find someway to make the switches compatible.

I would of said 4 but quietly accepting defeat is never an option unless your French.
No offense to any Frenchmen in the audience.
« Last Edit: October 01, 2017, 04:06:52 pm by neo »
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Offline bitseeker

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Re: Fluke 8200A read problem.
« Reply #65 on: October 02, 2017, 12:57:27 am »
It's good to see you're back up on the horse, neo. Sounds like there's a good chance the 8000A parts will work out. If the number of pins and contacts is the same, it may just work straight away without having to remove the contacts. That'd be ideal.
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #66 on: October 02, 2017, 01:58:18 am »
Electrically speaking, they are perfect, its the physical case of the switch that worries me on a few points.

It is not the exact same switch; same electrical characteristics, including footprint, but it is slightly different.

I can't work with the contacts i am far too much of a clumsy oaf and  i should have known better than try to begin with.

I don't have a junk 8000A and  i can't just go about playing around wantonly with it given its age.

I will admit that i prioritize the life of this 8200A over an 8000A but i cannot in good conscience wreck an 8000A that works.

I have drifted past the point of really knowing how to fix it.

It's good to see you're back up on the horse, neo. Sounds like there's a good chance the 8000A parts will work out. If the number of pins and contacts is the same, it may just work straight away without having to remove the contacts. That'd be ideal.

You will find that i am very stubborn, some would say to a detrimental level. Take for example that my first project was a clock which took me a year, i was stubborn enough to wind up with a clock out of it (why it took me a year drags us back to the point i said in red).
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #67 on: October 02, 2017, 02:11:13 am »
Could you provide me with an 8200A part number for the switches?

The way i see it i have three options,

A) Buy drop in replacements
B) Buy a broken 8000A and have someone better than me do the work on it to transfer contacts.
C) Buy a broken 8000A and find someway to make the switches compatible.

I would of said 4 but quietly accepting defeat is never an option unless your French.
No offense to any Frenchmen in the audience.

The problem is that the manual appears to show the switches (all of them) as a single assembly - S1 thru S11 - Switch assembly, FUNCTION & RANGE, part # 291492, Qty 1.  Despite the fact that the manual shows replacement of a single switch, I don't see a part number anywhere for just one, and of course the cage code associated with the assembly part number refers to Fluke as the manufacturer, so I don't know if they made the entire switch (quite possible given how vertically integrated some of these companies - HP and Tek come immediately to mind - were at the time, and how much they made themselves rather than buying from other manufacturers), or bought the modules and assembled them themselves.  I need to do more digging.

If you decide to go with option b or some variation thereof, I'd be happy to do the mods for you - I have a good desoldering station and the other associated tools that would be needed.

First let us do some more digging; perhaps someone can offer a suggestion for a replacement switch that won't involve 'organ harvesting' from a different meter...

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #68 on: October 02, 2017, 02:15:25 am »
neo -

Could you get some photos of the 8000A switches with something next to them for scale (a ruler, a postage stamp, a coin...), then do the same for those in the 8200A?  They /might/ be compatible, and just look a bit different - I know you said nothing protrudes out the back when actuated.  If the bodies are the same, it might be feasible to integrate them into the rails of the 8200A.

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Offline neo

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Re: Fluke 8200A read problem.
« Reply #69 on: October 02, 2017, 02:22:10 am »
neo -

Could you get some photos of the 8000A switches with something next to them for scale (a ruler, a postage stamp, a coin...), then do the same for those in the 8200A?  They /might/ be compatible, and just look a bit different - I know you said nothing protrudes out the back when actuated.  If the bodies are the same, it might be feasible to integrate them into the rails of the 8200A.

-Pat

Sure, give me a minute.
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #70 on: October 02, 2017, 02:43:03 am »
 :rant: I discovered what i think to be a fatal flaw, the 8200A has them sit slightly up off the circuit board and the 8000A switches don't have pins that long

Pictures below.
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #71 on: October 02, 2017, 02:50:15 am »
Hmmmm....  Pin length would be an issue, but if the plungers and contacts are the same, perhaps an organ transplant for the switch might be possible.

Let me think on this for a bit, and also try to see if anything else uses such switches.  It wouldn't surprise me if other Fluke meters do, and perhaps one of the other manuals shows a part number for an individual switch.

-Pat
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #72 on: October 02, 2017, 02:51:49 am »
I know of three other fluke meters that use these switches, the 8300A, the 8400A and the 8600A.
« Last Edit: October 02, 2017, 03:49:55 am by neo »
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #73 on: October 02, 2017, 04:30:46 am »
I've done a bit more digging.  It appears that similar switches are also used on the Fluke 8375A - a 19" nixie bench multimeter.  That one shows a range switch assembly part number of 398232, and also showed a range switch (possibly a single unit) part number 355404.  Unfortunately, web searches on those part numbers have proven to be fruitless.

I'll see if I can come up with anything else.

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Offline bitseeker

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Re: Fluke 8200A read problem.
« Reply #74 on: October 02, 2017, 06:54:27 am »
It's good to see you're back up on the horse, neo. Sounds like there's a good chance the 8000A parts will work out. If the number of pins and contacts is the same, it may just work straight away without having to remove the contacts. That'd be ideal.

You will find that i am very stubborn, some would say to a detrimental level. Take for example that my first project was a clock which took me a year, i was stubborn enough to wind up with a clock out of it (why it took me a year drags us back to the point i said in red).

Well, when it comes to fixing things, that stubbornness can be the persistence that leads to a working device. I wouldn't worry about it too much. Plus, you're among like-minded folks here who know first hand what it's like when things don't go as intended or when you just can't let go of what some would consider a lost cause. Beyond-economical-repair isn't always a dead end. Sometimes, it's just a speed bump. :-+
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #75 on: October 08, 2017, 02:00:21 am »
I've done some thinking, no need to run to the bomb shelters they are innocuous thoughts, only one switch is permanently knackered so if i could just get some one with better fine motor control to reassemble them i would be golden.
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Re: Fluke 8200A read problem.
« Reply #76 on: October 08, 2017, 02:52:56 am »
That sounds good. They don't even have to know any electronics. A neighbor, perhaps?
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #77 on: October 08, 2017, 03:22:58 am »
That sounds good. They don't even have to know any electronics. A neighbor, perhaps?

I live in the middle of nowhere, as such i have two neighbors. One is an old man whose hands shake worse than mine and the other....... lets just say we have a long history and a feud. Any other neighbors are what you would call hillbillies and they won't talk to me because i am still an outsider after 3 years here  :-DD
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Offline Cubdriver

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Re: Fluke 8200A read problem.
« Reply #78 on: October 08, 2017, 04:01:29 am »
Any possibility of finding the missing contact?

If you want, I'd be willing to take a crack at reassembling it if you send the interconnect/display assembly to me.  It's small enough that it shouldn't be too much to ship.  If you're not in a mad rush to get it up and running again, I'd say let's wait for a bit and see if something that contacts or switches could be pilfered from turns up.  I might be headed out west again in time for the TRW swap meet, and could look there to see if anything useful turns up...

-Pat
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Offline neo

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Re: Fluke 8200A read problem.
« Reply #79 on: October 08, 2017, 07:48:16 am »
Its not just a missing contact, two are bent one is missing as is the spring. I know i screwed up on one. I could ship it to you, so long as i know you are expecting it, i assume this forum will serve as record of it if i did that.

With the remaining bits and bobs from the switches i had an old test tube vial which i filled with isopropyl and put them in that, also side their springs. All the other bits are also in little vials, though none in isopropyl, and all the vials i put in a ziploc bag. Best way i could think of to keep track of all of it, screws included, without completely reassembling the thing.

Also of note the M \$\Omega\$ switch would have to desoldered to be taken apart due to a standoff on the board. Desoldering the switches entirely MIGHT be required to get them back together correctly.

No mad rush but this is, for lack of better term, one of my dream multimeters so i just want it to work, i have a build your own fluke 8200A kit only with the switches missing.   :-DD
« Last Edit: October 08, 2017, 07:51:43 am by neo »
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Offline bitseeker

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Re: Fluke 8200A read problem.
« Reply #80 on: October 09, 2017, 02:06:43 am »
I live in the middle of nowhere, as such i have two neighbors. One is an old man whose hands shake worse than mine and the other....... lets just say we have a long history and a feud. Any other neighbors are what you would call hillbillies and they won't talk to me because i am still an outsider after 3 years here  :-DD

Wow, only two neighbors. That does sound remote. Thank goodness for the Internet and shipping. :-+
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