[sdiy] D-70 red goo of death - not epoxy, maybe polyurethane

[Bob Weigel]

On 1/28/2013 6:13 PM, Dave Brown wrote:
> I heated up some water in a glass jar in the microwave (I'll have to get a
> junk pan to do this in).  I went up to about 150 degrees F.  It softens the
> goo enough that you can scrape most of it out.  If there was a weight still
> in the key, then you can pry it out with a small screwdriver.  Then you can
> dunk the key again and soften the goo and scrape the rest out.
>
> The metal weights are a mess but I can put them in a pan and boil them.  I
> think that will work pretty good.  I will have to have a second pan because
> they are so sticky you can't set them down on anything.
>
> I'm still left with a film all over the inside of the key.  I tried
> reheating it and then using a Q tip but the cotton just sticks to the
> remaining goo.  Just for fun I poured some baking soda into the water and it
> reacted and I got some crud floating on top.  I immersed the key in again
> and used the Q tip and I could clean the key out really well.  It isn't
> perfectly clean, but clean enough that nothing will ever drip out and it
> looks fine.
>
> I tried gluing one weight in using silicone.  I think that will work nicely.
> The issue is I have to do this 60 more times!    I think the film floating
> on the water will preclude doing more than a few keys before I have to
> change the water.  It stays hot enough long enough that I think I can just
> use the microwave to heat it up.
>
> I still need some tips on silver / carbon paint.  I can find some silver
> epoxy, but I am not sure I want that.  I'm thinking of something I can mask
> and then paint back on.  I did find these at Mouser but Ouch at the price.
>
> 590-8420-P Chemicals SILVER CONDUCTIVE PEN 0.3 oz $23.01
> 590-842-20G Chemicals SILVER PRINT 20G ( 3/4 oz) LIQUID $45.02
>
> Dave
>
> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Dave Brown
> Sent: Monday, January 28, 2013 3:25 PM
> To: 'Bob Weigel'; synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] D-70 red goo of death - not epoxy, maybe polyurethane
>
> I think I agree with this.  The synth isn't worth the hassle of dealing with
> harsh chemicals and possible accidents.  The goo does soften at fairly low
> temperatures.  I found I could get it off the flex circuit board by heating
> it up with my hot air gun, scraping the excess off, and then cleaning it up
> with a Q tip and lacquer thinner.  Lacquer thinner tends to dissolve the goo
> when it is more fluid when hot.
>
> I think heating the keys in water may be a good way to go.  With the hot air
> gun I can soften and scrape the stuff out of a key where they weight has
> fallen out.  With those keys with the weights still in them I don't think
> this would work very good.  The issue with heating in water will be to make
> sure the soften goo doesn't get all over the keys.
>
> So, I am now left with how to repair the flex circuit boards.  There are two
> small sections where the traces are damaged.  I assume these are a thick
> film paint so I probably need something to paint over them.  They look like
> possibly silver-based.
>
> At the edge connectors the silver traces went to the edge (and are no
> missing) and then had a thicker coating over them to form the actual
> contact.  I assume I would want to paint down a silver higher conductivity
> paint and then layer over that a thicker carbon/black coating.
>
> I haven't looked yet for conductive paints.  Any suggestions for a high and
> medium conductivity paint?
>
> Dave
>
> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Bob Weigel
> Sent: Monday, January 28, 2013 2:49 PM
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] D-70 red goo of death - not epoxy, maybe polyurethane
>
> I've usually just peeled the stuff off of keys when it gets away but I've
> never had to clean up the whole mess...but seems to me you could just put it
> in hot water that isn't hot enough to deform the keys.  This stuff melts at
> around 110 degrees F or so I think since it melts in the air at temps near
> that.  Don't boil it for sure, that warps the keys.
> I've heard of people doing that.  lol.  But when you get it warmed up the
> weight should come out and clean all the adhesive gel off with a scrubber or
> whatever and that should be the easiest I'd think.
>
>
>
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>
>    
RV goop is a pretty ideal adhesive for putting them back in btw.  It 
tends to stay like rubber a bit and it never fractures like rtv even 
though rtv is probably find for this too. I just find myself using goop 
for everything and rtv winds up drying in the tube.  lol.  I never lose 
any goop.  3.88 a tube at wal-mart in the rv stuff.  Speaker repairs and 
all kinds of great uses.  I even laminated it to re-create the plastic 
rib on the back corner of a dx100 once and have done a lot of other side 
break repairs with it.

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