What is this flaky dust in my multimeter? - Page 1
Forum section: electronics / testgear

author: TimNJ
author_rank: Super Contributor
timestamp: October 27, 2017, 03:23:33 am
content: Hi all,I just received a Keithley 2010 that I bought off eBay. It was manufactured in approximately 1999 according to the date-codes on the ICs. It's in good condition as far as I can tell.I have it apart to perform some preventative maintenance, namely replacing the electrolytic caps. Immediately upon opening it I noticed a flaky dust substance coating certain components. It's almost as if the dust was electrostatically attracted to certain components(?) It's most predominately on the front/back jack switch, but also on the vacuum fluorescent display, power transformer and AC inlet. It's semi-opaque and has a bit of an amber color to it. It almost has a fiber-glass texture to it and is kind of gritty.Since I first noticed it on the push button switch, I thought it might be switch lubricant that dried up? The expansion slot was covered and there is no fan in this unit so it doesn't seem likely that it was from the outside, but who knows.Any ideas? It doesn't seem to stop anything from working but doesn't seem good either. Picture is attached.

author: iainwhite
author_rank: Unknown
timestamp: October 27, 2017, 03:40:44 am
content: Possibly Zinc Oxide?

author: TimNJ
author_rank: Super Contributor
timestamp: October 27, 2017, 03:56:27 am
content: Thanks. What could be the source of that?Sent from my iPhone using Tapatalk

author: iainwhite
author_rank: Unknown
timestamp: October 27, 2017, 04:08:19 am
content: Oxidization of the zinc plating on the steel parts - maybe the switch uses zinc plated steel?It may not be that - just a possible explanation.

author: Pinkus
author_rank: Frequent Contributor
timestamp: October 27, 2017, 07:07:15 am
content: Maybe somebody did use some low quality contact spray (or just tried WD40) on this switch?

author: capt bullshot
author_rank: Super Contributor
timestamp: October 27, 2017, 07:30:12 am
content: Looks like old and detoriated foam plastics. Like the stuff Sennheiser used with their headphones to ensure people had to buy new earpieces every so and so years. Sometimes found inside old equipment where it was used for mechanical or acoustical damping but has detoriated to some kind of sticky dust.

author: ealex
author_rank: Frequent Contributor
timestamp: October 27, 2017, 10:11:45 am
content: I've seen something like that in old equipment.in my case it was just on some of the pin headers and IC sockets.the metal itself was not affected in any way .it did not seem conductive but i brushed it just to be sure it won't gather moisture.might be something from the plastic itself that's slowly leaking out and re-crystallizing.

author: Zucca
author_rank: Unknown
timestamp: October 27, 2017, 10:31:39 am
content: Another infected patient here?See:https://www.eevblog.com/forum/repair/counter-repair-enertec-schlumberger-2618/

author: TimNJ
author_rank: Super Contributor
timestamp: October 27, 2017, 12:59:31 pm
content: Quote from: ealex on October 27, 2017, 10:11:45 amQuote from: capt bullshot on October 27, 2017, 07:30:12 amYeah it definitely has a petroleum-based glisten to it. I don't see anything that looks like a culprit from within the case but perhaps it's something to do with the plastics.Since the unit powers up the display works and doesn't throw any error codes, it doesn't seem conductive, but I haven't really tested it much yet.Thanks.

author: TimNJ
author_rank: Super Contributor
timestamp: October 27, 2017, 01:53:29 pm
content: Quote from: zucca on October 27, 2017, 10:31:39 amAhh that looks really similar. Not exactly bubbly like he describes but similar look for sure. Looks like it wasn't a problem for him in the end.Thanks!

author: Diabolo
author_rank: Regular Contributor
timestamp: October 28, 2017, 01:56:38 am
content: Hello,The PCB is varnished with spray and the bubbles come from the solvent that has evaporated during drying.Diabolo