How can I remove years of nicotine staining from a Fluke 8842A? - Page 1
Forum section: electronics / testgear

author: Specmaster
author_rank: Super Contributor
timestamp: September 12, 2018, 08:41:06 pm
content: I've just added to my meter collection a fully kitted out with all the options a 8842A and although last known calibration was 1995, it still appears to within pretty much still in calibration. It was last owned by a smoker and the case and the fascia along with the top row of buttons have all been caked with nicotine from the smoke and changed colour.Any idea what I can do to redress this discolouration?Also the display and input panel have 2 ribbon cables connecting it with the main PCB, I cannot see how this cable is disconnected, I've never seen a plug/socket like this before. Anyone ever removed the display before?I need to disconnect it in order to remove the rubber button assembly for cleaning.

author: tkamiya
author_rank: Super Contributor
timestamp: September 12, 2018, 09:13:46 pm
content: I typically remove such plastic pieces and soak in dish detergent + water for overnight. Then put it in a large box, use my ozone generator to remove the stink. I did something like that for a radio a smoker owned. After 2 treatments, tabacco smell went away.

author: Specmaster
author_rank: Super Contributor
timestamp: September 12, 2018, 09:17:47 pm
content: Quote from: tkamiya on September 12, 2018, 09:13:46 pmSmell is not the issue, that has near enough gone now as the original owner passed away and they gear has been dormant for awhile and so the worst of the smell has dissipated, its the colouring its left that is my particular problem.

author: mc172
author_rank: Frequent Contributor
timestamp: September 12, 2018, 09:21:19 pm
content: Are you sure it just hasn't gone that way because it's old, like most old gear made from ABS tends to go?

author: Specmaster
author_rank: Super Contributor
timestamp: September 12, 2018, 10:23:32 pm
content: I'm positive that it is due to nicotine staining because where the handle has been folded flat under the meter, the case has remained the original colour the attached photo may show this discolouration to better, the fascia and buttons is the main concern, as you can see from the 2 8840A below, the coulour of the buttons clearly shows bad discolouration.

author: TheSteve
author_rank: Unknown
timestamp: September 12, 2018, 10:28:00 pm
content: Could be smoke, could also have just been exposed to lots of UV. I'm leaning towards UV.

author: Specmaster
author_rank: Super Contributor
timestamp: September 12, 2018, 10:40:36 pm
content: Would UV leave everything sticky then?

author: BrianHG
author_rank: Super Contributor
timestamp: September 12, 2018, 10:48:01 pm
content: If it is not UV, then, place some VIM on a paper towel or J-Cloth and test clean a corner to see if it works.Note that VIM is a very, very, very mild liquid abrasive. I used it to clean an old Amiga 4000 before ebay sale and it has done wonders. Note that after using VIM, you will need to clean it off, I tend to spray some Windex on a Jcloth or paper towel and wipe off a few times.Warning, always apply the cleaner to your cloth/tower, never spray directly on the hardware, or, it will get into the electronics.If the test shot of VIM works, you will need to disassemble your front panel for proper cleaning. If it doesn't work, then you plastic has browned due to sun exposure. There are more fancy chemicals and procedures to clean that, however, these methods probably aren't safe for the membrane keypad.When I say VIM, I meanthe squeeze bottle white liquid creamy stuff, not the spray bottle.See photo:

author: langwadt
author_rank: Super Contributor
timestamp: September 12, 2018, 11:13:37 pm
content: as others mentioned it might be UV. But try some spray for cleaning in the kitchen, it needs to be basic, something with ammonia will do too

author: tautech
author_rank: Super Contributor
timestamp: September 13, 2018, 12:01:11 am
content: Tooth paste rubbed with fingers.

author: TERRA Operative
author_rank: Super Contributor
timestamp: September 13, 2018, 12:16:25 am
content: For tobacco goop I use iso-alcohol on PCB's and other stuff etc, and dish washing detergent on more sensitive bits that don't mind a bit of water.I recently cleaned up an old mini portable CRT TV that was gooped up that belonged to an old Japanese chain smoker (seems to be a past-time of the older generation) and it came up beautifully.PCB's went from a brownish olive colour back to their original 80's style deep green.

author: cvanc
author_rank: Frequent Contributor
timestamp: September 13, 2018, 12:29:06 am
content: I will 2nd the idea of a household cleaner with ammonia in it. I've had good luck cutting through smoker's residue using it.

author: Specmaster
author_rank: Super Contributor
timestamp: September 13, 2018, 12:30:18 am
content: All the internals are spotlessly clean, no air vents or fan to allow the fumes to enter, just looking at the PCB you would think it had just left the factory.

author: xrunner
author_rank: Super Contributor
timestamp: September 13, 2018, 12:37:29 am
content: For nicotine stains it'sSimple Greenif you can get it.

author: BrianHG
author_rank: Super Contributor
timestamp: September 13, 2018, 12:53:51 am
content: Be careful of concentrated heavyduty detergents and cleaners. You may rub the silkscreen print off the keypad, and maybe other text on the panel.

author: Muttley Snickers
author_rank: Unknown
timestamp: September 13, 2018, 01:53:26 am
content: Quote from: Specmaster on September 12, 2018, 10:23:32 pmThere are a number of products including test equipment which are prone to varying degrees of discolouration due to exposure to UV and this has been discussed previously on the forum, from memory it was something to do with Bromine being used in the plastics.The GW GFG-8016G Function Generator shown below and another one I have both came out of a local university where the chance of them being exposed to cigarette smoke was highly unlikely, the one shown probably sat in the same place and wasn't moved very much either.The electronics department class rooms had large windows on each side and this is evident as the front face and one side of the generator has noticeable discolouration and the other side has no bikini line at all, the other generator does have discolouration but no bikini line so the handle was probably removed much earlier.

author: james_s
author_rank: Super Contributor
timestamp: September 13, 2018, 03:53:21 am
content: I use some stuff called Oil Eater, it's fantastic for this sort of thing. Just a few weeks ago I restored a Heath GC-1000 that had so much nicotine in it that the inside of the smoked plexi face was foggy enough to make the display blurry. I took it all apart and sprayed it down with Oil Eater and it washed it right off.

author: innkeeper
author_rank: Unknown
timestamp: September 13, 2018, 04:58:56 am
content: shh... the secret is to use vinegar glass cleaner from windex.comes right off. no soaking or fancy process.

author: Specmaster
author_rank: Super Contributor
timestamp: September 13, 2018, 08:14:58 pm
content: Quote from: Muttley Snickers on September 13, 2018, 01:53:26 amThese photos look similar to my meter for colour, however, on the function generator the handle when not being used as a tilting bail, sits on the top and would certainly explain the bikini line effect which mine also has. Now comes the puzzling part, the handle on a Fluke 8842A when not used to tilt the display towards the user, sits flush under the meter which both sunlight or UV from fluorescent lighting would not normally reach.This was one factor that made me assume that was smoke related as it is free to roam as it seems fit, especially if the smoker exhaled in the general direction of the meter, which mounted on a shelf would be the case. The other thing that sort of cemented that relationship in my mind was that the whole meter felt sticky to touch which nicotine contamination often does, BUT it did not smell like an old ashtray either which I would have expected smoke damage to smell like. I did ask the seller if his father smoked and he confirmed that he did and sort of predetermined in my mind that I was dealing with smoke damage.Another odd thing was that when I removed the handle, the section that was adjacent to the underside of the meter was dirty, the outer side of that section was not?When I go shopping tomorrow I'll look for some of the products mentioned in this thread and try them on the underside of the case.

author: macboy
author_rank: Super Contributor
timestamp: September 14, 2018, 01:36:41 pm
content: You are lucky that the front panel plastic has no silkscreened labels which might be damaged by harsh cleaning of any type. So you are free to try more things than otherwise. I have removed yellowing from a few Keithley front panels, and they all had silkscreening. I damaged one badly (before knowing what I was doing), but now I can get them back to a nice neutral grey without issue. My problem was age yellowing of the ABS, not nicotine.I'd guess you have a combination of both nicotine staining (which is obvious) and some discoloration of the ABS plastic. Debates linger about the cause of the ABS yellowing, but there are solutions. I have had excellent success with high strength hair bleach ("40 volume") in a cream format (not liquid). After disassembly and cleaning, I liberally brush the peroxide cream onto the plastic, put it in a plastic or glass container, cover with plastic food wrap (to avoid drying out), and place in full mid-day sun to get high UV. Rotate every 10 minutes, for good sun coverage, re-applying if necessary. Should be done in 30 or 40 minutes in my experience. Don't leave it excessively long or the colorant in the plastic (and any silkscreened labels) will start to be bleached as well. This process may be effective against the nicotine stain also but I couldn't say. Definitely clean the oily residue as well as possible first, because the water-based peroxide needs to get into the surface of the plastic.

author: cvanc
author_rank: Frequent Contributor
timestamp: September 14, 2018, 03:17:06 pm
content: Quote from: james_s on September 13, 2018, 03:53:21 amIt seems they make several products, can you be more specific?http://oileater.com/

author: Fungus
author_rank: Super Contributor
timestamp: September 14, 2018, 03:40:58 pm
content: If somebody gave me a meter coated with 1mm of tabacco residue all over it I'd soak it in gasoline overnight to dissolve the residue, throw a match in next morning, then go look for another one.It's gonna be inside it, on the wires, everywhere. I really hope it doesn't have a fan to gradually blow all those years of residue out of it and back into the room.

author: JanJansen
author_rank: Frequent Contributor
timestamp: September 14, 2018, 05:20:23 pm
content: Might be fire retardant stuff in combination with UV indeed.Use whitening toothpaste it contains bleach ( dont use it for your teeth it can damage your toothflesh )

author: xrunner
author_rank: Super Contributor
timestamp: September 14, 2018, 05:38:55 pm
content: Quote from: Fungus on September 14, 2018, 03:40:58 pmSomebody gave me a Kenwood TS-120S transceiver once that was used by a smoker. The fan drew in all that smoke and coated everything inside with nicotine. It was disgusting. I picked a few valuable parts out of it and threw the rest of it away.But here's the sad part - you can clearly see what the smoke does to things, so can you imagine what coats your lungs ...

author: Specmaster
author_rank: Super Contributor
timestamp: September 14, 2018, 06:05:51 pm
content: Quote from: Fungus on September 14, 2018, 03:40:58 pmHa ha, that made laugh, But seriously all the internals are spotlessly clean, no air vents or fan to allow the fumes to enter, just looking at the PCB you would think it had just left the factory. The general consensus is that it is more UV damage with a light bit smoke damage. Smoke was so long ago that you cannot smell it now, thank goodness for that.TBH I think right now I'd settle for just getting the buttons nearer to their original colour. The case is for the best part hidden within the stack.

author: mc172
author_rank: Frequent Contributor
timestamp: September 14, 2018, 09:43:07 pm
content: UV does the "bikini effect":

author: Specmaster
author_rank: Super Contributor
timestamp: September 14, 2018, 10:20:24 pm
content: Quote from: mc172 on September 14, 2018, 09:43:07 pmYes I understand that it will do that, but how does the UV get beneath the meter, I can understand the front, top and or sides may well be exposed to UV especially if the source is sunlight, but surely it would safe to expect the underside of the meter should suffer UV exposure as it would be "in the shade" and yet that is where the "bikini" effect has happened?

author: mc172
author_rank: Frequent Contributor
timestamp: September 14, 2018, 11:07:34 pm
content: Look around your room/lab/whatever during the day. There is light underneath your instruments, it's just not as much as the front. Shade is not absence of light - think of it as a bit less light.How would the smoke get under there unless the guy was blowing it deliberately under there, which is extremely unlikely?

author: Specmaster
author_rank: Super Contributor
timestamp: September 14, 2018, 11:13:53 pm
content: Very true but isn't that a bit like saying that I can get a nice tan even indoors? The yellowing is same degree under the meter as it is on top and I have meters that many years older but they have not yellowed nor show even the slightest hint of a bikini effect where the handle is either.

author: 3roomlab
author_rank: Frequent Contributor
timestamp: September 14, 2018, 11:32:26 pm
content: isnt peroxide the normal go to for whitening of plastics?

author: xrunner
author_rank: Super Contributor
timestamp: September 14, 2018, 11:38:08 pm
content: Quote from: 3roomlab on September 14, 2018, 11:32:26 pmYep. What I use in shown in the attachment. Paint it over the plastic and cover with saran wrap so it doesn't dry out in the sun. After a few hours in bright sunlight you will be amazed. Done it many times with no ill effects and works like a charm.

author: usagi
author_rank: Frequent Contributor
timestamp: September 14, 2018, 11:43:02 pm
content: peroxide treatment is only temporary. the yellowing returns, even for parts stored in total darkness in temperature controlled humidity controlled storage.

author: james_s
author_rank: Super Contributor
timestamp: September 15, 2018, 12:38:31 am
content: Quote from: cvanc on September 14, 2018, 03:17:06 pmI didn't realize there was more than one. I use the regular white bottle cleaner degreaser. It's similar to Simple Green but I find it to be more effective at removing grease and oil. Wear gloves though, it's supposedly non toxic but it sucks the moisture right out of your skin.