I saw another baby swing repair thread here so I thought I'd post as well. It's an older Fisher-Price My Little Lamb™ Cradle ’n Swing that runs on four D batteries. Since I didn't want to replace them every week, I added a DC jack and used a 6v AC adapter. It worked fine for a long time, but recently started acting up. The swing itself works fine, but the music no longer plays, and the spinning mobile wont turn off. I can't figure out the problem. I didn't notice any domed or leaking capacitors. Do you know what could be causing the malfunction? I attached pictures of the control box circuits. Let me know if you need other, or more detailed pictures. Thanks!

 

Thanks for posting nice clear photos. This doesn't always happen.

Do you have a voltmeter?

Measure the voltage output of the adapter and make sure it is DC and not AC. What is written on the adapter?

 

Thanks for posting nice clear photos. This doesn't always happen.

Do you have a voltmeter?

Measure the voltage output of the adapter and make sure it is DC and not AC. What is written on the adapter?

It says 6VDC 800mA and measures 9.9v (under no load)

 

The swing itself works fine...

By that do you mean that the swing is still getting the normal assist to keep swinging?

 

By that do you mean that the swing is still getting the normal assist to keep swinging?

Yeah, the swing motor and speed control still work fine

 

Hello,

The music is likely produced by the black blob on the last picture with U3 near it.
When that is broken, you are out of luck.

Bertus

 

I tend to agree with Bertus - there is not much hope once you spot a black blob.

Does the mobile spin while music plays, I mean are the two related? You might get the mobile to spin by bypassing the controller.

 

Ah bummer. What's under the black blob?

The two can be controlled independently. In the first picture, the lower left switch controls the music. "0" is off, and the other positions are for different sounds/songs. The lower right switch turns the mobile on and off. The mobile works now, it just wont turn off. It spins no mater the switch's position. That isn't really a problem, I mainly wanted to get the music going again because it's sentimental to my wife

 

In the sixth pic, showing the circular pcb tracks of the main rotary switch, there appears to be some gunge bridging the track gaps at about the 3 o'clock position. Give the tracks a good clean in case gunge is shorting the track segments and preventing turn-off.

 

In the sixth pic, showing the circular pcb tracks of the main rotary switch, there appears to be some gunge bridging the track gaps at about the 3 o'clock position. Give the tracks a good clean in case gunge is shorting the track segments and preventing turn-off.

@Manbearpig
Most issues are related to hardware like connectors, switches and wire insulation and, finally, capacitors. They are rarely silicon chip related. I agree with Alec that the rotory PCB switch is likely the issue. Try cleaning it with a good quality pencil eraser. This will polish it up. Put some light oil (even Vaseline) to keep it from oxidizing again soon.

If it doesn't work After that, check the other switches and make sure the connectors are pushed in all the way.

 

Ah bummer. What's under the black blob?

It's a custom IC on the board itself, as opposed to a chip soldered onto the board, like the other big IC in the picture. It cannot be removed or replaced.

I agree with the others about cleaning and checking connections. (You really have no other choice!) Look for wire breaks and such - don't assume anything.

Electrolytic capacitors age and go bad with no visual change, but I would save looking at those until you are farther along.