Buzzing Twin-Solutions

[paddy]

Hi all,

Just thought I would post some info on some of the sources of buzzing
that I found during a recent repair to a Fender Twin Reverb. My customer
complained that there were strange buzzing noises present when he
played various notes. I decided to hook up my signal generator and I did
notice buzzing at a number of frequencies. Tightening all of the screws
took care of some of these. Some adhesive foam stripping placed
between the chassis and the cab got rid of another buzz. The next noise
I found was coming from the electolytic cap housing. These caps had been replaced and had not been secured properly. Some hot melt glue
and foam held them steady and stopped this noise. The most interesting noise source was the jewel light lens. It was spinning around at one
frequency, as the lens had come unglued. A new jewel fixed this. Last but not least, the tilt back legs also decided to buzz at one frequency. The
customer always uses these and they made no noise when in use so I
told him and we left them as they were.
This all took quite a bit of time, but I think it was made much quicker
through the use of a signal generator.
I hope this post is useful to someone.

Cheers,
Paddy

[Structo]

Yeah, those sympathetic vibrations can drive you crazy trying to find the source.
Good idea with the signal generator.