Crackling from a solid state circuit

[Craig405]

Hi,

I have a pair of Yamaha PC4002M power amplifiers, theyre really beasty an i love them! But recently ive noticed one of them (i run them bridged per speaker) has developed an intermittant crackling sound. Its fairly loud and sounds like dry twigs being snapped. It tends to happen once the amp has been on for an hour or two and does seem to go away eventually.
Actually turning it off and on again seems to eliminate it.

Its nothing before the amp causing it as i turned the input attenuator right down and still heard it. Im finishing uni this summer and will have time to investigate further.. what is likely to be causing this?

I know we have many solid state masters here! im thinking old electrolytic or bad solder joint but my experience isnt vast.

Suggestions are much apprecited!

 

[Jan Dupont]

I sounds most likely to be a bad solder joint.
Check and resolder solder joints.

 

[Craig405]

I was afraid of that, theres a lot of transistors to unmount to get at the solder side.

Thanks very much!

 

[Jan Dupont]

Try tapping carefully on the different parts of the PCB and on the components with the backend of a screwdriver, while listening for the cracking sound.

But be carefull not to touch anything with your fingers

Or you may use cooling spray if you got it 😉

 

[Craig405]

Thats a good idea! might just be able to apply solder from the top of the PCB once i find the component. Would save potential damage of pulling the board out.
Ill see how it looks.

 

[Jan Dupont]

Let us know 😉