[[email protected]]

Hi, I am going to recap a AMPEG Jet-II reissue guitar amp with PCB
construction. I found that they applied a yellow goop around many
parts of the board, mostly on power caps and big resistors. I think I
can remove the goop and get to the parts, but just curious why they did
that, microphonics mabye ? (on the caps?? ) . Do I need to reapply
some glue there after I've done with the new caps? Did Glue Gun works?

Thanks in advance.

Al.

_you know what to remove to reply.

[Phil Allison]

wrote in message
oups.com...


** Boring Groper Alert.


Hi, I am going to recap a AMPEG Jet-II reissue guitar amp with PCB
construction.



** Boring.....


I found that they applied a yellow goop around many
parts of the board, mostly on power caps and big resistors. I think I
can remove the goop and get to the parts, but just curious why they did
that, microphonics mabye ? (on the caps?? ) . Do I need to reapply
some glue there after I've done with the new caps? Did Glue Gun works?


** The " yellow goop " is to hold the parts in place so they do not vibrate
loose, fracture their wire leads and fall off the PCB. Kinda obvious
really.

The "goop" is normally ordinary contact adhesive which has proved to be
VERY BAD when used with electronic components - since it is **highly
corrosive** to copper metal leads and becomes **electrically conductive**
with age and even modest heat.

Silicone sealants are far better for the job - but AVOID any that smell
like acetic acid. Suitable one are labelled as "neutral cure", "non acid"
or being suitable for use with metals.





......... Phil

[Ned Carlson]

wrote:

Hi, I am going to recap a AMPEG Jet-II reissue guitar amp with PCB
construction. I found that they applied a yellow goop around many
parts of the board, mostly on power caps and big resistors. I think I
can remove the goop and get to the parts, but just curious why they did
that, microphonics mabye ? (on the caps?? ) . Do I need to reapply
some glue there after I've done with the new caps?

The goop is there for one of two reasons: 1. Hold parts on the board
while it's wave-soldered 2. Keep parts from rattling when the
amp is played. If rattling noises are a problem, stick the
caps to the board with some silicone glue. Easy to find at any
auto parts store.

That's a fairly new amp, the caps already crapped out?

--
Ned Carlson
SW side of Chicago, USA
www.tubezone.net

[[email protected]]

Thank you. So I assume that glue gun will also work.

The amp is made around 1992 I guess. I got it cheap second hand
(really cheap) because the sound is very distorted when played at any
volume. I check it and one of the EL84s is red hot compared to the
other. I guess it is either the tube or the biasing. I opened up the
chassis and found another problem. One of those big cap is mounted
touching a 5W resistor, and its top is already buldging out, I though I
better replace that too with other repairs.

Sincerely,
Al.

[RickH]

I have blobs of goop sticking many of the wires on my 1962 Ampeg Reverb
Rocket (model R12) to the chassis, (PTP wired with turret board). It
looks like they gooped many of the wires to the chassis in this amp
too, dont know why. To make matters worse one of the wax-coated paper
caps overheated and melted it's wax down the chassis too. It's a lot
of goop to deal with as I want to change out the wax-coated caps and
the electro's, but that damn goop keeps getting in the way.

Was this goop common in this 1962 case too? What would the goop have
been made of in 1962? parafin? Some of it appears to be slightly
hardened, thicker globs are still softer.



wrote:
Hi, I am going to recap a AMPEG Jet-II reissue guitar amp with PCB
construction. I found that they applied a yellow goop around many
parts of the board, mostly on power caps and big resistors. I think I
can remove the goop and get to the parts, but just curious why they did
that, microphonics mabye ? (on the caps?? ) . Do I need to reapply
some glue there after I've done with the new caps? Did Glue Gun works?

Thanks in advance.

Al.

_you know what to remove to reply.

[Lord Valve]

OK, Goop Freaks...

First, to the dude who wants to use hot glue instead:
Are you nuts? It's a *tube* amp. It gets *hot*. Use
silicone glue from the auto parts store like Ned said,
or get some electronics-grade "RTV" from somewhere.

To RickH - sometimes wires are glued down so that
they stay where they are supposed to stay. This is
done to prevent oscillation or minimize hum. Leave
everything just like it is. If you need to move anything
to make repairs, make sure you put it back where
it was. There's some mojo involved in lead dress,
and you obviously don't know anything about it.

LV




RickH wrote:

I have blobs of goop sticking many of the wires on my 1962 Ampeg Reverb
Rocket (model R12) to the chassis, (PTP wired with turret board). It
looks like they gooped many of the wires to the chassis in this amp
too, dont know why. To make matters worse one of the wax-coated paper
caps overheated and melted it's wax down the chassis too. It's a lot
of goop to deal with as I want to change out the wax-coated caps and
the electro's, but that damn goop keeps getting in the way.

Was this goop common in this 1962 case too? What would the goop have
been made of in 1962? parafin? Some of it appears to be slightly
hardened, thicker globs are still softer.

wrote:
Hi, I am going to recap a AMPEG Jet-II reissue guitar amp with PCB
construction. I found that they applied a yellow goop around many
parts of the board, mostly on power caps and big resistors. I think I
can remove the goop and get to the parts, but just curious why they did
that, microphonics mabye ? (on the caps?? ) . Do I need to reapply
some glue there after I've done with the new caps? Did Glue Gun works?

Thanks in advance.

Al.

_you know what to remove to reply.

[Chris Hornbeck]

On Tue, 31 Oct 2006 13:00:26 +1100, "Phil Allison"
wrote:

The "goop" is normally ordinary contact adhesive which has proved to be
VERY BAD when used with electronic components - since it is **highly
corrosive** to copper metal leads and becomes **electrically conductive**
with age and even modest heat.

Truer words were never writ. This is a pervasive problem with
all kinds of commercial electronics, and we're all going to
see it lots more in our lifetimes.

This crap needs to be painstakingly dug out by hand, then
the metal surfaces examined with a bright light and hand magnifier.

We ignore Phil's post above at our peril.

Much thanks, as always,

Chris Hornbeck

[Chris Hornbeck]

On 31 Oct 2006 11:06:53 -0800, wrote:

So I assume that glue gun will also work.

No! Please don't do it.

Everybody please re-read Phil's post in this thread. He's
talking about time bombs in all kinds of electronics. Just
say no to (at least) hot glues for electronics.

All good fortune,

Chris Hornbeck

[RickH]

Lord Valve wrote:
OK, Goop Freaks...

First, to the dude who wants to use hot glue instead:
Are you nuts? It's a *tube* amp. It gets *hot*. Use
silicone glue from the auto parts store like Ned said,
or get some electronics-grade "RTV" from somewhere.

To RickH - sometimes wires are glued down so that
they stay where they are supposed to stay. This is
done to prevent oscillation or minimize hum. Leave
everything just like it is. If you need to move anything
to make repairs, make sure you put it back where
it was. There's some mojo involved in lead dress,
and you obviously don't know anything about it.


LV Thanks for the (harsh) info. Actually this goop is separating from
the chassis in most places so movement can happen anyway. Most of it
is starting to dry up and atomize, it's a mess, but the amp works fine
except for the melted/blown-open reverb coupling cap. Wherever the
glue sat the wire insulation is brittle at those spots and the chassis
oxidized with glue separated. If you ask me applying this was a waste
of Ampegs manufacturing time, wires would not have moved anyway unless
someone got in there and moved them. I've built radios that had more
critical lead issues than a guitar amp, and never glued them outside a
little parafin dripped onto the enameled wire chokes after I wound and
tuned (squeezed/stretched) them to frequency.

[Ned Carlson]

RickH wrote:


LV Thanks for the (harsh) info. Actually this goop is separating from
the chassis in most places so movement can happen anyway. Most of it
is starting to dry up and atomize, it's a mess, but the amp works fine
except for the melted/blown-open reverb coupling cap. Wherever the
glue sat the wire insulation is brittle at those spots and the chassis
oxidized with glue separated.

The capacitor people I know tell me that the capacitor gunk,
at least, is some kind of wax. There's lots of different kinds of wax,
with different melting points and hardness, and in some case it's
a combination of petroleum and beeswax, and may *look* like plastic.
Either way, some *careful* application of heat ought to liquefy it
enough to mop most of it up.

If you ask me applying this was a waste
of Ampegs manufacturing time, wires would not have moved anyway unless
someone got in there and moved them.

This may have been put in to avoid rattling. It was also cheaper than
using the old fashioned wire lacing.




--
Ned Carlson
SW side of Chicago, USA
www.tubezone.net