I am about to start repairs on a Kenwood ham radio that originally used
Sonybond to secure several of its VCOs. The main VCO has become
unstable and voltage exists within the Sonybond to ground, so it has to
be removed.

Initial recommendations from years past suggested carefully scraping or
cutting away miniscule pieces until none remained all the while
carefully preserving circuit components. Since the process is long and
tedious, I wonder if any better ways have been developed for removing
this stuff and preserving components? Thank you.

On Tue, 11 Jul 2023 16:41:59 -0400, Saunderlin <none@no.com> wrote:

>I am about to start repairs on a Kenwood ham radio that originally used
>Sonybond to secure several of its VCOs. The main VCO has become
>unstable and voltage exists within the Sonybond to ground, so it has to
>be removed.
>
>Initial recommendations from years past suggested carefully scraping or
>cutting away miniscule pieces until none remained all the while
>carefully preserving circuit components. Since the process is long and
>tedious, I wonder if any better ways have been developed for removing
>this stuff and preserving components? Thank you.
Once the bond turns brown, scraping is the only way I know.

On Tue, 11 Jul 2023 16:41:59 -0400, Saunderlin <none@no.com> wrote as
underneath :

>I am about to start repairs on a Kenwood ham radio that originally used
>Sonybond to secure several of its VCOs. The main VCO has become
>unstable and voltage exists within the Sonybond to ground, so it has to
>be removed.
>
>Initial recommendations from years past suggested carefully scraping or
>cutting away miniscule pieces until none remained all the while
>carefully preserving circuit components. Since the process is long and
>tedious, I wonder if any better ways have been developed for removing
>this stuff and preserving components? Thank you.

The type (there are two types apparently) that I had in a radio and had
gone conductive - I managed partially to dissolve ie soften with
Silicone sealant remover (a Beaufix product I had in the garage IIRC).
The remover wants to dry out so to stop this soak the brown stuff then
cover with clingfilm for 24 hours, pull off with fine tweezers what you
can, then repeat the treatment once or twice more. Slow and fiddly as
hell but it got there in the end.
No other solvents I tried would even touch it, and I tried a bundle.
Might be worth a try.. C+

Saunderlin wrote:
> I am about to start repairs on a Kenwood ham radio that originally used
> Sonybond to secure several of its VCOs. The main VCO has become
> unstable and voltage exists within the Sonybond to ground, so it has to
> be removed.
>
> Initial recommendations from years past suggested carefully scraping or
> cutting away miniscule pieces until none remained all the while
> carefully preserving circuit components. Since the process is long and
> tedious, I wonder if any better ways have been developed for removing
> this stuff and preserving components? Thank you.

In one case even scraping/cleaning it did not fix the issue, apparently the board had absorbed some bond and was slightly conductive by itself. I ended up doing some mod to the circuit to reduce its sensitivity.

It was a board with a power amplifier IC and a power transistor used to cut power to the IC when in stand-by. It had a small transistor to drive the base of the big one and resulted in so much gain that some microamperes leaked through the sonybond kept both transistors turned on causing noises through the speakers when in stand-by. I was tempted to remove the small transistor because the driving signal had more than enough current to drive the power transistor directly (then I would have had to invert it somehow), but it was enough to add a pull down resistor to overcome the sonybond leak.