Vintage sound activated disco light

[Robio]

Hi all, 'hope you can help with my 1970's very un-groovy problem. I have two sound activated color organ lights made in the 70's that pulse to sounds. They're the type that have a mic built in with a seemingly simple little board, the lights are Christmas bulbs and they don't have any pot switches, just the on/off inline on the a/c cord. One of them works fine but the other I bought off Ebay just strobes constantly. Can anyone tell me the best way to diagnose what's defective? I'm not knowledgeable in electronics but I have a multimeter and I figure if one is working correctly there might be a way to compare the two and spot what went bad. I can post a pic if that will help.

 

[Six_Shooter]

Posting some pictures of the unit and the circuit will help.

 

[Robio]

Thanks for replying Six_Shooter, will get some up soon as I find the blamed usb cord to my camera!

 

[Robio]

Pics added

Had to use my phone camera, hope these are clear enough, lemme know.
(edit) I did get my camera working for the board closeups.


http://i801.photobucket.com/albums/yy300/Robiorich/11-07-13_002507_zpseaf6a42b.jpg

http://i801.photobucket.com/albums/yy300/Robiorich/11-07-13_002746_zpsf8cf3314.jpg

http://i801.photobucket.com/albums/yy300/Robiorich/end_zps3199e777.jpg

http://i801.photobucket.com/albums/yy300/Robiorich/top_zps09c92331.jpg

http://i801.photobucket.com/albums/yy300/Robiorich/side_zpsdf29c7ef.jpg

http://i801.photobucket.com/albums/yy300/Robiorich/corner_zps031a66b2.jpg

 

[Robio]

heya, what do think about the blue 25v cap? It's bulging out from the bottom a little. Would it make sense that the lights strobe constantly instead of blinking to sound/music and the cap could be the cause?

 

[(*steve*)]

The cap looks fine to me (but that doesn't say it is)

 

[Robio]

I meant the purple cap, my bad. Does it look a little pushed out and not flush with the board like the gray one to you?

 

[(*steve*)]

Same diagnosis.

What does the other side of the board look like?

 

[Robio]

You wouldn't believe the other side, it was made in the '70's so there is enough solder to make four of these little boards by today's standards. It's all solid and very thick, I think they used a mig welder.

I've decided to just replace all the components as they're so few. Normally you just go buy a new one at Walmart, but they simply don't make these anymore and I love the cool factor albeit cheesy it's part of their charm.

 

[Robio]

UPDATE: Turns out it was the purple 25v cap. Anytime you've got a cap bulging from the lead end and not totally flat with the board, indication that it's toast.

So, for a package of eight for $1.97 online it's working like brand new (if it were the 1970's). Pretty hip and groovy if I do say so.

 

[Robio]

UPDATE: Turns out it was the purple 25v cap. Anytime you've got a cap bulging from the lead end and not totally flat with the board, indication that it's toast.

So, for a package of eight for $1.97 online it's working like brand new (if it were the 1970's). Pretty hip and groovy if I do say so.

 

[(*steve*)]

Excellent. The cap didn't look bulgy to me. Where was it bulging, and in which image could you see it?