I have a kiddie ride sound board that was working fine the last time I used it, a few months later it was unplugged and moved to storage when removed from storage it now has a really bad hummm no matter where or what location it is plugged into I visited the manufacture who tried replacing the large cap with no luck he accused me of plugging it into 220v which I know never happened he said there were several broken parts on it and wanted a 100.00 to fix it, seeing I already just barely over the warranty year bought it for 220.00 and that it does not appear to have 100.00 parts on it and last I don't have a 100.00 to pay to fix it here I'am. I have already replaced all the black capacitors on it minus the large one the vendor replaced still humming anyone have any ideas as to where to go from there?

 

A bad hum is probably a shorted output amp IC.

Check if the 8pin IC is a LM386 amp IC, if so replace it.

 

I'm thinking more likely a bad capacitor, with no filtering on the power supply. Can't tell from the picture, but does this cap look bulgy to you?

 

It's possible, but he did say he tried replacing the big capacitor.

Normally with an IC amp they will short out the high side of the amp IC output stage, so the PSU is connected directly to the speaker. The symptom is a loud nasty "buzz".

With a decont photo of the PCB we could be more helpful!