hybrid opamp epoxy archeology

hello,
I was trying to get the coating off an hybrid ACN opamp that blew on my sony mxp2000 console. anyone of you know about some solvent or way to get it off without ruining all the components? the coating is black and shiny, I guess this is epoxy...
thanks
maxime

That topic comes up from time to time. It seems a heat gun (or a hairdryer) and a fine sharp tool get the most votes.

ok, I 'll try that!
best
maxime

I doubt heat will help. perhaps freeze it and it will get brittle, be easier to chip off. Id use freon, an ice pick and a wee hammer.

no solvent will probably help you now, but Acetone is useable as a thinner before epoxy cures.

why not figure out the pinout and make a new amp to replace it? I am familiar with that console and the sound of those hybrids. it is pretty nice but not sacred. I would like to see the schematic if you trace it out.

mike p

http://www.groupdiy.com/index.php?topic=209851#209851
[quote author="mnats"]Use some dichloromethethane, sold as "Attack" in the US. Soak it for a while and it will turn hardened epoxy into a gel-like substance that can easily be broken into little chunks.[/quote]
http://www.ganoksin.com/orchid/archive/200411/msg00354.htm

I know if you do a search you get pages that seem to imply that epoxy can't be broken down but honestly, I've done it many times using the above solvents.

Curious .... what did it do to the components .....

that is what they call "aircraft remover"

I got rid of the epoxy with an heat gun.
I think it's possible to make a clean job with just mechanical ways but this hybrid was dead already...
thanks a lot you all
maxime

[quote author="maxime"]I got rid of the epoxy with an heat gun.
I think it's possible to make a clean job with just mechanical ways but this hybrid was dead already...
thanks a lot you all
maxime[/quote]

How about some pics? :grin:

Maxime,

The US company Dynaloy have a lot of different "potting/encapsulation removers" and I think the type for epoxy is the "Dynasolve 165" ??

You can find them here: http://www.dynaloy.com

--Bo

thanks for your replies,
I 'll post a picture soon.

maxime

here's the pic:
http://i156.photobucket.com/albums/t8/maximebdsn/DSCN2307.jpg

broken, but readable.
it really does not look like the spares I got from an mxp 2900 master section

anyone have an idea about this red sandy component ?

best
maxime

It looks indeed very different to the ones found in the MXP2900.
Did you manage to get the hybrid from the MXP2900 working in your MXP2000?
I've no clue about the red sandy blob....

no, I didn't get the mxp 2900 acn hybrids into the 2000 yet. I'll have to do it someday for sure. the thing is that the master section hybrids are +-18volts powered and +-15 in the group modules, though they look the same..
are the acn hybrids the same on the master and group strips on the 2900?

bye
maxime

Doc Hoyer says soaking it in acetone works, but you have to let it sit for a few days.
If you can't wait, like me, it is (NYD won't let me say i'ts" incorrectly anymore) always the heat gun. :green:


Oh, that Beyer?
Doc saw them demonstrate the "coil wound directly on the core" routine at AES back in the 60's. They use a black dot on the bobbin flange that gets ditected by a photo cell for counting turns. The bobbin flange sits on a wheel that spins for winding.

Yes, same hybrid. Also, like in your mxp2000 they get + - 15v in the group modules and + - 18v in de master modul.
I have to say that the hybrids from the mxp2900 look very diferent to the mxp2000 ones. Maybe they sound different as well.
I'm looking at one of my hybrids now and it has 1 IC (probabely Tl072) 4 resistors, 4 caps and two transistors. All SMT except for the transistors.

Are you sure that the on on the pic is a ACN (summing) Hybrid? Not a line driver Hybrid?

yes, i'm pretty sure the hybrid is a summing op amp.
glad to know that group and master use the same opamps at different voltages. I 'll probably change the resistor values around too, to conform to the mxp 2900 schematics.
I'll keep you informed once done (helas not in the very near future because of work)..
best
maxime