Polytone Mini Brute IV

[DPM309]

I will be getting a Polytone MB IV to work on that has an issue with crackling/static noise after the amp has been running for a couple of hours. Read all of the post here on Polytones and did not find any one with the same problem. Should I be looking at the input IC chips? From what I have read here, most of the issues with these amps lie in the preamp section or input PCB. The first thing I am going to do is to clean all of the jacks and connections. Any other ideas or suggestions?

Thanks,

Dan

[booj]

Sounds temperature related. A heat gun and some freeze spray may help find it while chop-sticking the board

[DGstrat]

I have worked on a few of these.
I recommend splitting the connection between the preamp and power amp and seeing if the noise is entirely within the poweramp.

Given that it takes time for the problem to occur, I would suspect the large resistors and caps in the power module in the bottom of the amp. In the cases I have seen with noise in the preamp, it has begun as soon as the amp was powered on.

Dave

[DPM309]

Thanks for all of the suggestions. I will let you know what I find when I get the amp later this week.

Dan