I was fed up with my multimeter switch/rotating dial being so fidgety and not always making the display work and having to wiggle it back and forth. also caused it to display error every so often. so I opened it up. and discovered an oily residue everywhere inside on the circuit PCB all around behind the contacts of the dial. I went ham at it with some isopropyl alcohol spray and a microfiber cloth. cleaning every nook and cranny of the contacts and PCB.
I also found some on the metal cylinder things that the probes slot into and cleaned that up as well.
put it back together and it seems to be working much better and more reliably. resistance setting works so much better i can detect the resistance of something down to the last decimal place of precision on the multimeters display. and with the good alligator clip leads clipped together it reads exactly 0.000 ohms on the dot. so i can even know if my multimeter test leads have resistance to them. i currently have some cheap probe/pointy leads that have about 0.2 to 0.3ohms of resistance on them. and my 10A alligator clip leads that have 0 ohms of resistance. What could be the weird oily residue i found inside the DMM? it was very clear looking oily liquid stuff.
I also found some on the metal cylinder things that the probes slot into and cleaned that up as well.
put it back together and it seems to be working much better and more reliably. resistance setting works so much better i can detect the resistance of something down to the last decimal place of precision on the multimeters display. and with the good alligator clip leads clipped together it reads exactly 0.000 ohms on the dot. so i can even know if my multimeter test leads have resistance to them. i currently have some cheap probe/pointy leads that have about 0.2 to 0.3ohms of resistance on them. and my 10A alligator clip leads that have 0 ohms of resistance. What could be the weird oily residue i found inside the DMM? it was very clear looking oily liquid stuff.
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Sounds like somebody else previously tried to clean it up with (maybe) WD-40.
it was bought brand new though. and looks like it was absolutely never opened. the internal glass display had absolutely no traces of dust or anything on it at all like it just came out of a clean room.
its so weird though! and i thought WD-40 left only a super thin film once it evaporates. not a clear liquidy thick oily substance. there was quite a lot of it and it didnt seem like it had dried up even the tiniest bit.
its so weird though! and i thought WD-40 left only a super thin film once it evaporates. not a clear liquidy thick oily substance. there was quite a lot of it and it didnt seem like it had dried up even the tiniest bit.
I cleaned several of mine last week for the same reason. Eratic display. One meter, about 10 years old and used lightly has quite a bit of wear on one of the 6 contact pads that run on the PCB tracks. Pcb tracks were polished but no real wear.
After cleaning off a surprising amount of dust and lint and gunk with straight alcohol it worked great. But after testing I decided maybe running dry wasn't best so put a little fader lube on it an then wiped it basically all off.
Time will tell if that is best but I don't like the wear on the one pad.
After cleaning off a surprising amount of dust and lint and gunk with straight alcohol it worked great. But after testing I decided maybe running dry wasn't best so put a little fader lube on it an then wiped it basically all off.
Time will tell if that is best but I don't like the wear on the one pad.
I have a nice collection of old meters, some very usable with no modern equivalents. The battery operated tube units all were originally lubricated on the switches. With time this failed and became more conductive so with the very high impedances used it was a serious problem.
The solution was to actually remove the switches and soak them in alcohol before adding a drop of modern lubricant and replacing them.
Another issue can be paper in oil capacitors leaking.
The last issue is plastic meter faces disco loring from age. A good plastic polish works, but after that you must replace the clear anti static coating. Scotch guard for that.
The solution was to actually remove the switches and soak them in alcohol before adding a drop of modern lubricant and replacing them.
Another issue can be paper in oil capacitors leaking.
The last issue is plastic meter faces disco loring from age. A good plastic polish works, but after that you must replace the clear anti static coating. Scotch guard for that.
Mine has a small burnt spot on the plastic front of the display cause my soldering iron touched against it for a split second by accident and theres absolutely no way to fix it without taking it apart. taking the plastic front cover off. and sanding and polishing it like crazy. and that would be more effort than its worth.
its not in the way or anything but its kinda annoying that is there and i cant get rid of it.
its not in the way or anything but its kinda annoying that is there and i cant get rid of it.
Hi Refugee1,
It really is time for a new meter! Those were old when I was calibrating equipment in 2000. I'm going to bet that most $50 meters are better than that one is. If you want a meter to go the distance, a Fluke or Keysight would be the best bets.
Those Beckman meters didn't hold calibration well, and we had many failures too.
Hi realflow100,
I would almost bet that your meter was a "B" stock unit sold as new. It had been returned by someone who tried to "fix" it. WD-40 wouldn't surprise me, but that stuff would probably have destroyed all the capacitors and zebra strip(s) to the display. Silicone oil or something similar might be what it was. A little silicone grease on the switch contacts would help extend the life of those contacts.
Hey Ed,
Thanks for the Scotch guard hint! That solves that problem with my old meters.
-Chris
It really is time for a new meter! Those were old when I was calibrating equipment in 2000. I'm going to bet that most $50 meters are better than that one is. If you want a meter to go the distance, a Fluke or Keysight would be the best bets.
Those Beckman meters didn't hold calibration well, and we had many failures too.
Hi realflow100,
I would almost bet that your meter was a "B" stock unit sold as new. It had been returned by someone who tried to "fix" it. WD-40 wouldn't surprise me, but that stuff would probably have destroyed all the capacitors and zebra strip(s) to the display. Silicone oil or something similar might be what it was. A little silicone grease on the switch contacts would help extend the life of those contacts.
Hey Ed,
Thanks for the Scotch guard hint! That solves that problem with my old meters.
-Chris
That old burned meter still works and I keep it for when neighbors want to borrow one so that when they are fixing cars I don't loose a good one. It is the right tool for that job.
Its last outing was to a 4X4 with a dead glow plug controller.
It limped away after a bit of wire was dabbed across from the battery to the glow plugs.
Its last outing was to a 4X4 with a dead glow plug controller.
It limped away after a bit of wire was dabbed across from the battery to the glow plugs.
Sounds like silicone fluid to me.
It has many uses - one as a mould release agent. Perhaps the case wasn't washed down after it was removed from the mould.
It's also used as a lubricant in some electro-mechanical interfaces (but more typically in grease form) perhaps they 'spritzed' a bit too much at the factory!
I use it at work inside fluid filled gauges / instruments but also in high speed shaft bearings on drive shafts.
It has many uses - one as a mould release agent. Perhaps the case wasn't washed down after it was removed from the mould.
It's also used as a lubricant in some electro-mechanical interfaces (but more typically in grease form) perhaps they 'spritzed' a bit too much at the factory!
I use it at work inside fluid filled gauges / instruments but also in high speed shaft bearings on drive shafts.
Oh, I´d attribute it way more to "operator error" than a factory one .
Silicone mold release *is* regularly used but quantities involved are minuscule, just a very light mist and most you feel is a slightly slippery surface, if at all; here realflow description hints at somebody getting trigger happy with a can of lubricant or "contact cleaner", petroleum or silicone based, a mess in any case.
Users can take suggestions literally the wrong way.
Heathkit famously mentioned once: "assembly instructions stated: cement diode to case ... kit builder filled the case with Portland cement !!!!"
Silicone mold release *is* regularly used but quantities involved are minuscule, just a very light mist and most you feel is a slightly slippery surface, if at all; here realflow description hints at somebody getting trigger happy with a can of lubricant or "contact cleaner", petroleum or silicone based, a mess in any case.
Users can take suggestions literally the wrong way.
Heathkit famously mentioned once: "assembly instructions stated: cement diode to case ... kit builder filled the case with Portland cement !!!!"
Hi JMFahey,
So, that kit would have been a solid state project, right?
I also agree, this has all the earmarks of someone who wasn't a professional. Plastic molded parts always go through a bath to clean them before heading on down the line for assembly or storage. I highly doubt that stuff was left from any manufacturing process you could think of. Now, repair? Absolutely! WD-40 is a favorite weapon of choice, and it is fairly destructive.
Most times when I was doing instrumentation calibration and repair, we might see something like what was described here. Excessive grease applied everywhere. Occasionally we even saw conformal coatings applied by the owner. Those PCB contact type switches don't work after that. Fortunately, we can remove that stuff, but it is still a PITA.
Once a customer presented his Teac cassette deck for service. It was squeaking, so he loaded it up with ... you guessed it. WD-40. The mechanism had to be stripped, cleaned and rebuilt, All the rubber of course, but also all the clutches. He did $250 worth of damage back in the late 80's.
If you're curious about it, he did achieve his goal. The deck no longer squeaked.
-Chris
That's priceless!
So, that kit would have been a solid state project, right?
I also agree, this has all the earmarks of someone who wasn't a professional. Plastic molded parts always go through a bath to clean them before heading on down the line for assembly or storage. I highly doubt that stuff was left from any manufacturing process you could think of. Now, repair? Absolutely! WD-40 is a favorite weapon of choice, and it is fairly destructive.
Most times when I was doing instrumentation calibration and repair, we might see something like what was described here. Excessive grease applied everywhere. Occasionally we even saw conformal coatings applied by the owner. Those PCB contact type switches don't work after that. Fortunately, we can remove that stuff, but it is still a PITA.
Once a customer presented his Teac cassette deck for service. It was squeaking, so he loaded it up with ... you guessed it. WD-40. The mechanism had to be stripped, cleaned and rebuilt, All the rubber of course, but also all the clutches. He did $250 worth of damage back in the late 80's.
If you're curious about it, he did achieve his goal. The deck no longer squeaked.
-Chris
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