kiddie ride sound board

[bulanek]

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?

[channelmaniac]

I'd start by checking for a solid, clean +5v power source out of that 3 terminal voltage regulator... it looks like it's gotten very hot and discolored the board a bit around it.

If that's good then check the clock on the CPU and the data/address/enable lines on the EPROM for activity

If all that looks good then take a scope and check the audio amplifier section to see if there is audio coming in but none coming out.

RJ

[bulanek]

I should have probably put a little more information the unit does work but there is a loud hummm even when the unit is not in use. The voltage regulator does not feel hot at all and the unit instantly once plugged in gives this hummm not over a period of time indicating a heat problem. I should also add that although I have successfully with help from people like on this forum fixed many many items I'm very much an amateur and do not own a scope. how would I check for the +5v on the 3 prongs? I tried testing it with the diode mode on the mm and appears correct.

[bulanek]

Oppps I should have started off by saying thanks for the reply.

[Foster]

Set the meter for DC voltage (VDC) and place the black (-) on the center pin (GND) and the red (+) on the right pin(Output).

The mounting tab for the regular is at the top of the device.

In your picture the tab is at the bottom edge of the board.

Pins
Input  GND  Output
The mounting/heatsink tab is also GND.

[channelmaniac]

Since you don't have a scope you can only shotgun parts to repair it.

I'd start with this: Next to the transformer is a bridge rectifier... It has little +/- and ~ symbols on it. Replace it.

If it has a short it would blow fuses... but if it's leaky you could get hum. It's cheap and it's easy to replace.

[bulanek]

Thanks it tested 5 volts, I have not had time to replace the rectifier yet, well have not had the time to go get it anyway. Anything else I should pick up while I'm at the store?

[bulanek]

Thank you to everyone that commented, channelmaniac is the winner it was the voltage regulator even though it tested 5 volts and didn't seem to get hot. after replacing the rectifier and a few other parts I found the problem. Wish it would have been the first part I changed would have been a 3.00 repair oh well better then 100.00 for someone else to fix what a rip off I actually almost spent that but I ordered a big bag of parts for the tool box for next project I come across.  I wish there was another company making kiddie sound boards I wonder how much it would cost to design one for a production run. This company is not so customer friendly, and I have some great ideas on how to improve it.

[channelmaniac]

Glad to help where I can...

Congrats on fixing it! There sure is a great feeling you get from taking something that isn't working right and reviving it.