remove epoxy resin from dbx vca module

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matthias

Well-known member
Joined
Jun 4, 2004
Messages
768
Location
germany / frankfurt
hello,

I have a broken dbx vca module, removed from a dbx119.

dbxvca.jpg


I think I'll replace everything with new components.
But at least I want to keep the metal can...

I aready tried to heat it up but it didn't melt.

Does anyone know if there's a chemical way to dissolve the epoxy resin?


thanks,
matthias
 
Prolonged immersion in dichloromethane will soften epoxy enough that you can dig it out. However, dichloromethane is not so easily found these days (it was widely used as a wood furniture finish remover in the old days) and you need to be careful to avoid breathing very much of it if you do find some.
 
When I had a bad DBX module, I gave up trying to remove the compound and paid through-the-nose for a reproduction unit. Removing the compound whilst retaining some semblance of what component values / types were used is not easy, to put it mildly.

This topic comes up regularly, some good links here: http://www.groupdiy.com/index.php?topic=915&highlight=potting

http://www.groupdiy.com/index.php?topic=18034&highlight=potting


Justin
 
Even if you do get it open and "clean" it would be very hard for common people (me, and i suspect you) to reproduce a discrete blackmer cell. The matching of the transistors are critical.
 
thanks, for your haelp...

I already have a schematic of the vca, but if there would be an easy solution to remove the epoxy I try to repair the module...
regarding the transistors there are some packages with matched transistors available, e.g. ca3096a or that300 series..
 
Modelmakers use dichloromethane quite a lot, as it is the ideal glue (rather solvent to melt the material surface) for sticking plastic materials like styrene and acrylic to each other without causing a mess. May be you can ask them or plastic material suppliers where you can get it (usually in large 5-litre brown glass containers). But you need to keep it covered in an appropriate container in the process as

1) It melts most standard plastic materials on the spot, so there are particular ABS or glass containers and natural hair brushes that do not react with it,

2) It vapourizes very fast (a brush stroke takes less than a second to dry out),

3) Your body soaks it quite fast too so you'd better avoid skin contact, although it won't immediately burn or irritate your skin like an acid or alkali liquid. Nevertheless, it's a hazardous chemical to your body. It looks like water as well, so it's too easy to confuse them with each other. Make sure you don't put your hands in it, or swallow it or let it go in your eyes. In the event of an accidental contact, just wash the body part with soap and water and you'll be fine. It dries out by the time you get to the sink anyway.

(A part of our business is in modelmaking/prototyping for over 20 years so we have it on the bench down on the shopfloor at all times.)

Good luck.

Mach
 
From the Defence Technical Center:

N-methyl-2-pyrrolidone has been used at 80 degrees C for several years to dissolve urethane foam potting. An investigation was conducted to determine if the solvent could be similarly used to dissolve rigid epoxy encapsulants. By increasing the temperature, N-methyl-2-pyrrolidone was shown to be an efficient solvent for stripping cured epoxy encapsulants from electronic assemblies. The investigation was expanded to include other materials, and the scope was expanded to include potential salvage of sealed switching units and other high cost components. Results, to date, show N-methyl-2 pyrrolidone to be an effective solvent for polysulfide, polyurethane, polystyrene, rigid silicones, and all epoxy systems investigated. N-methyl-2-pyrrolidone appears to be unusually safe, presenting a comparatively low risk of fire or toxicology problems. (Author, modified).
 

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