My first GC(lm3886) +fire works+ please help

[rs1026]

I built a lm3886 amp using Rod's design for lm3876.I used same component values.The amp worked perfectly well for 1-1.5 hours without any problem.But suddenly it went up in smoke with fire all around.I oberved that 100nf supply capacitor was totally burnt to ashes.Few neigbouring components turned black but luckily was not burnt.

Inspite of this I powered the amp and it played perfectly just like before.Inspite of bypass capacitor being quite near to 3886 the amp chip was not damaged.

I have used 100nf tantalum capacitor for bypassing and rest everything is electrolytic.Should I change the capcitor values or should I replacee even 100nf with electrolytic ones.

Please help.

[mcs]

Originally posted by rs1026
I have used 100nf tantalum capacitor for bypassing and rest everything is electrolytic.Should I change the capcitor values or should I replacee even 100nf with electrolytic ones.

Are you sure they are tantalum? The 100nF decoupling caps should be plastic film or ceramic caps.

Best regards,

Mikkel C. Simonsen

[peranders]

Are you sure it was 100 nF and at least 35-40 volts? It couldn't have been 100uF something low voltage? Did you get + and - right for the caps?

As Mikkel says, I recommend also 100 nF/63V polyester or ceramic.

[rs1026]

I am sure it is tantalum.But there is no volatge rating on that.I guess as you guys mentiond polyester would be better.I have some 0.1uf ployester caps it says P26104K but then there is no voltage ratng on that too!!

[mcs]

I have never seen 100nF polyester caps with a lower voltage rating than 63V, so I think they should be OK.

Best regards,

Mikkel C. Simonsen

[rs1026]

Thanks guys,I think I will use polyester capacitor itself.i have cemaic disc type of same value but thought of using ployester ones this time.