Guitar amp problem

[joe-90]

This isn't an appliance but is about electronics so:

I've got an old trannie guitar amp that is about 25 years old. For no reason it suddenly developed a mains hum and distorts badly, it is a fault that got worse over a few hours and I sometimes got a loud pop out of the speaker.

Removing the guitar lead doesn't affect the hum.

I'm guessing that it might be one of the large electro caps in the power supply that has dried up as there is one near a 5 watt resistor that gets warm.

There's no sign of any visible fault but the amp isn't worth getting repaired professionally so I thought it might be worth a few quid on parts from Maplins.

Any thoughts anyone?

 

[joinerjohn]

What make of Amp is it Joe???

 

[joe-90]

It's a Sessionette 75

 

[Mickymoody]

I reckon you sussed it Joe, caps and heat right next to them for 25 years isn't good. Is the top of the cap ballooning out? Has the cap leaked on the board?

When the amp is unplugged, try a diode test across the cap, both ways, the reading should increase, although this is a very basic test.

Replace all the large caps at the same time, otherwise another one might pop, due to the new one.