Marshall mg15cd channel switcher button flaky

[rm9]

Hi,

I have a 20 year old Marshall mg15cd amp.
The clean channel works well, but when I press the channel button to switch to the overdrive channel, then I don't hear anything.

If I jiggle the button for a while then sometimes I can find a spot that makes the overdrive channel work.

Any ideas on how to fix it?

Thanks.

[Jazz P Bass]

First thought is a flaky solder connection at or near the switch.

Second is a dirty switch.

Third is a faulty switch.

[rm9]

First thought is a flaky solder connection at or near the switch.

Second is a dirty switch.

Third is a faulty switch.

Thanks.
what's the easiest thing to try first?

[Jon Snell]

Thanks.
what's the easiest thing to try first?

Clean the contacts and examine the soldering.

[rm9]

Clean the contacts and examine the soldering.

Any tips how to clean it?
I don't have much experience with electronics.

[Jon Snell]

A can of Contact Cleaner is usefull in this sort of case.
I have no clue on your country for supplier but as an example try this; https://uk.rs-online.com/web/p/lubricants/1368550/
A squirt in the contact area works wonders and also is useful to stop the scratchyness of worn volume/tone controls.

[J M Fahey]

Electronics shops carry different contact cleaners.
Worst case, use a small squirt of WD40, in all cases trying it to get inside the switch.

Absolute worst case, try to inject some kerosene (what Brits call paraffine) inside the switch and turn it O-OFF many times,

I mean the strong smelling usually reddish fuel used in lamps, not the white "wax" solid sometimes used in candles.

In any case, that switch is already worn, so consider buying a new one.

[rm9]

Thanks , I ordered a contact cleaner and should be here soon. do I need to take the amp apart or can I just spray it through the button whole?

[Jon Snell]

If you pull the knob out exposing the inner push actuator, hold the nozzle pipe against the switch aiming between the actuator and cover of the switch. A quick squirt should do the trick.
Switch on and off a dozen times to move the contact cleaner around inside the switch.
When evaporated re fit the knob.
Hope that cures your problem.