Issues with Studiomaster mixer

[widdly]

Hi

I've got an old Studiomaster Mixdown Gold 16-8-2 mixer. It has a couple issues I'd like to sort out.

1.) There is an intermittent humming in the main channel outputs. It comes and goes but it isn't present in any of direct outputs or bus sends.

2.) There is a quite loud buzzing sound coming from the transformer.

I'm not sure if these issues are related. Any tips to solve these problems?

[winky dinglehoffer]

Transformer hum is often due to laminations in the transformer getting loose & vibrating against each other. A replacement transformer would be the easy solution--if you can find something appropriate.

[Scodiddly]

Sometimes it's the power supply rectifier(s) that are going bad, shorting some extra current and causing the power transformer to work harder.

[widdly]

I think a new transformer would be a good start.

I've noticed the noise in the main channel out's only comes on after the mixer has been running for a while. Maybe heat related?

[Nick Sevilla]

I think a new transformer would be a good start.

I've noticed the noise in the main channel out's only comes on after the mixer has been running for a while. Maybe heat related?

Most likely bad capacitors in the power supply. They are not quite yet failing, but they are announcing their impending doom.

[Scodiddly]

I think a new transformer would be a good start.

I'd really recommend going with rectifiers and caps - they are cheap and almost certainly the source of your problem.

And if it still persists, I'd bet something further along is pulling too much power and causing the transformer to hum.

[widdly]

Ok thanks for the advice guys. Caps and reg's would be cheaper and easier to source.

[emrr]

Intermittent hum may also point to physical connections. If it’s full of any sort of Molex or ribbon connections, I’d exercise those to clean the contacts.