Marshall MG100Dfx switch on noise

[Tubetec]

Normally a reliable enough unit these from my experience,
Customer complains of loud noise at switch on ,
First few times I powered it up no problem apart from a noisy fan bearing which Ive seen a lot on that series of amps , it rattles a bit for a while then the noise goes away , a small drop of light machine oil on the fan bearing sorted that out .

Anyway I pull the PCB ,  everything everything seems good , I tidy up some of the wiring with a few extra cable ties mainly just to stop various wires crossing over each other in close proximity. I re-assemble ,switch on and the all merciful  crunch crackle bang reveals itself . I dismantle the output chip/fan assembly to find some of the heat sink compound across the legs of the TDA 7293 output ic , I clean,  re-assemble , seems to be working faultlessly now again.

This amp may not have been getting  much use , it could be an issue with the filter caps charging or needing to reform . Ill leave it on for an extended period and see how we go . Any ideas or suggestions welcome.

 

[Tubetec]

I confirmed with the owner the amp wasnt used in a long time .
Ive run the amp over two days for around 16 hours in total ,everything appears to be normal ,
no more hiccups , burps or farts .

I did take the time to look around online at posts related to problems with this series of amp , most forums were inhabited by individuals who felt the need to rubbish this , in my opinion, fairly robust and solid sounding amp .
The particular model in question here is a few years old ,made in India and I cant see any reason why it wont give many years of service as long as its shown some love and used once in a while.

Anyway hopefully this post will come in useful to someone somewhere and stop them being convinced by the buzz-killer gobshite know it all's its only fit for scrap