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 Post subject: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Sat 22, 2018 6:14 am 
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Location: Hammond, Ind.
One of my older navy VTVMs is just caked with the MFP lacquer. Everything inside was just caked. And it’s not very easy to deal with in my case. I’ve dealt with this stuff before, it’s usually not laid on this heavy. I don’t know what to do about it. It’s an unavoidable problem.

All of the parts inside are mounted on these weird solder lugs that also act as rivers on a phenolic board. This board, all the parts and lugs, they are just covered. I need to replace some parts, but this stuff is really making that a challenge. I cant just use paint stripper or all of the part specs willl disappear along with the MFP. Acetone doesn’t do a great job either. The parts specs are somewhat important as a schematic for this is somewhat hard to find. I have one, but it’s the only available copy.
Anyways, I tried chipping some MFP off of a lug. I couldn’t get it all of course, but I tried. I tried soldering to the somewhat clean lug and the MFP around it seems to boil along with any I didn’t remove prior to this. It then hardens into a brittle substance that is annoying and likes to damage soldering tips. It makes a big mess. I think it’s causing crap solder connections and causing a lot of extra work. Is there any way to remove it without erasing part specs?

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Sat 22, 2018 10:37 am 
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...causing a lot of extra work. Is there any way to remove it without erasing part specs?...
NOPE, you just have to cut, hack and scrape the stuff off. BTW it is not lacquer, its most likely epoxy of some sort.

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Sat 22, 2018 2:21 pm 
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For those not familiar with military MFP materials, they contain a fungicide in a heavy coating material. The fungicide is bad for people as well as fungus, and it may still be active even after all these years. You need to take care to wash your hands before eating or smoking, and do not breath the fumes when soldering. There was no chemical remover for it; if repairs were necessary you were instructed to scrape, chip, and wire brush the material off before soldering--and then re-apply new MFP coating to the exposed places when you were done!

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Sat 22, 2018 3:49 pm 
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Joined: Sep Tue 30, 2014 6:08 am
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Location: Norfolk, VA
Parylene, thy stuff is a pain!!

Get some "Tetra-H" or deal with it mechanically.

The Navy taught Parylene removal in older school - two days worth of labs. Yes, a pain.

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Sat 22, 2018 4:44 pm 
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If only they had been able to figure out a way to put it on the inside of capacitors .....

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Sat 22, 2018 7:44 pm 
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I’ve been researching this stuff for awhile. Not trying to prove anyone wrong or anything, but It’s not parylene. It’s not that gummy modern stuff. I imagine that’s a real pain to deal with. It is thinned lacquer. I found an original video for the application. Pretty cool video. I don’t know if the lacquer is toxic when dried, but I imagine it is if you eat it. The video says it’s toxic when sprayed, but any paint is really. I think they forgot to thin the lacquer or mask in my case. I am going to try whatever nasty stuff I have to remove it. I’ll post the results. I imagine it’s easy to remove now knowing that it’s lacquer.

http://www.criticalpast.com/video/65675 ... equipments

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Sat 22, 2018 10:00 pm 
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Joined: Feb Sun 17, 2008 11:36 pm
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Location: Dayton, Ohio
Since it is a VTVM, it is probably not too complex. (just guessing as there are no pictures). I would be tempted, if it were mine, to find a surplus tag board somewhere and replace with all new components and toss the old board out.

Charlie


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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Sun 23, 2018 12:45 am 
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Already tried. No more stock of something this old. This unit is from 1951 from what I've read. Its got a bunch of bad resistors that need to be replaced.

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Sun 23, 2018 2:23 am 
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Location: Norfolk, VA
It would probably help if you posted the model (TS- or ME- number) - many of us have worked this stuff in the past and could help, if only we n=knew what you were dealing with. Others may have a hangar queen on a shelf for parts...

The military contract dates mean nothing with most test equipment - the ME-26, for example, was made from late 1955 to 1966 in all of it's versions (original, B/U, C/U and D/U) Others were briefer runs, but my point is the "date" of a military item has to be discerned from the model and serial numbers, lacking that, the RETMA date codes within the unit.

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Sun 23, 2018 4:39 am 
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TS-505/U. Not A/U or D/U, the first variation. Production didn't last long for this thing. It was obsolete by the time it was manufactured. Info about it is scarce.

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Mon 24, 2018 2:15 am 
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In the good old days, I modified some WW II vintage military gear for ham use. This involved de-soldering and soldering to MFP coated terminal strips.

All I did was leave the iron on long enough to burn the stuff away and then proceed as normal. The stuff smelled pretty bad when burning but somehow I survived.

Regards,

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Mon 24, 2018 11:17 am 
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Yep smoke and fumes are part of it, and now days lots of folks all worked up about it, but just stay up wind of the smoke. This little guy doesn't get much use, but its handy on occasion.

Image

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Mon 24, 2018 1:50 pm 
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I thought that the anti fungal coatings contained arsenic or such to make sure nothing grew?

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Mon 24, 2018 8:08 pm 
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Joined: Feb Sun 17, 2008 11:36 pm
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Location: Dayton, Ohio
jimjimmunster wrote:
Already tried. No more stock of something this old. This unit is from 1951 from what I've read. Its got a bunch of bad resistors that need to be replaced.


I meant a NEW tag board of the right size and number of terminals, populated with all NEW parts.

I took a broken "spring hook" and on a grinder made a long thin chisel, sort of like a "Jewelers Screwdriver only much longer and sharper, to "chisel" chunks of the MFP off of connections.

A DREMAL tool with a small dentist's "burr" bit can also remove much of the MFP off of connections.

Just remove what you need to un-solder and don't limit yourself to just one tool or method.

Have fun,

Charlie


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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Tue 25, 2018 5:51 am 
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I did what was stated earlier also before making this post also, I tried just burning through it. The smoke smells like pine. Probably not good to inhale. I have a small Weller iron and it has trouble getting through the stuff. Its only 25 or 35 watts. Takes too long to heat the stuff and probably damages parts. Should have used a fan when I was trying. I was just wondering if there were anything better ways to clean the stuff. I think I'll try the wire brush or chiseling at it. Might just keep doing acetone and a toothbrush while trying not to damage any paint. Il maybe try acetone and a wire brush.

Anyone have suggestions of a good hot soldering gun? I have an old Weller, I just don't like it. The tip is a little challenging to deal with and it doesn't get hot as fast as I would like it to. Everything has to be perfect to get results. Takes about 20 seconds for it to warm up for some reason. Maybe its broken. Ill look into that some time later. But does anyone have good views about a particular gun?

There's no way I'll remake that board with my limited funding and time. Time especially. I would like to, but I just cant. I paid 10 bucks for this and don't expect to put that many resources into it. I'll have to work with what I have. I might go at it with the chisel though. I have a small chisel with some old taps somewhere. Sounds a little destructive but I trust that it will work. Might even borrow a Dremel with a wire wheel. I think the burr would be a little bit destructive if I make a mistake. Acetone is pretty good at softening this stuff up too, might speed things up.

Thank you for all of the helpful suggestions,
Bill Thorner

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Tue 25, 2018 10:03 am 
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Location: Sunbury, Ohio 43074
A few random thoughts.... a higher powered Weller gun is cheap, pretty readily available. I've even seen them at many estate/garage sales for $5. If you gun is not heating enough, it's usually due to the tip nuts being either loose, or the tip itself being oxidized where the nuts hold it into the gun. Try some steel wool on the hooked ends there.

As for removing the conformal coatings, try a mini wire wheel in a Dremel tool??? Just wear a facemask if you do this.

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Tue 25, 2018 3:52 pm 
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Joined: Jul Tue 21, 2009 1:38 pm
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Location: SW WA state
wazz wrote:
I thought that the anti fungal coatings contained arsenic or such to make sure nothing grew?


I believe the traditional stuff is a lacquer with about 1% Copper Naphthalene...

-Tom


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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Wed 26, 2018 6:22 am 
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Location: Long Beach Ms. USA 39560
Your local cheap-tools place has a imitation Dremel tool kit for $9.00 +/- it includes the wire wheel .
Disclaimer: I only buy stuff at Harbor Freight, no stock or other interests.
Pat

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 Post subject: Re: MFP (Moisture/Fungus Proofing) Causing Problems
PostPosted: Sep Wed 26, 2018 12:39 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1073
Location: St. Louis, MO, USA
GO to your dentist and ask for a scraper (tooth scraper?) tool. You can scrape moisture fungus proof coating easier than a pointed tool. BTW, I was told years ago that this coating has mercury salts in it to retard fungus.

Dennis


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