Blinking led issue.

[Sparky12]

Hello all, new to this, and it looks like a great group here! I have an issue with a group of led lights that blink at a certain speed on a Buddha statue that my wife brought from Vietnam.
For years the leds blinked brightly, but over the past year, I have noticed them getting dim, and they will eventually get to the point that they are hard to see them blink. The funny part is, that when you unplug it for a moment, then plug it back in, the leds blink brightly again. And it will stay that way for a few days, then may start dimming down again.
It has a small circuit board inside it, and I do not see anything obvious wrong with it. It has a rheostat attached to the board, that you can regulate how fast the leds blink, but it seems to be working. I am an electrician, and not super in tune with electronics. But my only idea might be perhaps one of the capacitors on the board might be breaking down, and over time is not holding the charge as long as it should? Any suggestions would be a great help, thanks!

 

[Nigel Goodwin]

Is it mains or battery powered?.

Assuming it's mains powered?, then a common cause would be high ESR electrolytic capacitors in the power supply.

 

[Sparky12]

It is a plug in statue. It was originally from Vietnam, and I think the mains there are 50 hz.
I had to find a small transformer that would work on 60 hz here, and that went ok and the statue worked fine for years. The problem creeped in, which made me wonder if it was a capacitor problem.

 

[Nigel Goodwin]

It is a plug in statue. It was originally from Vietnam, and I think the mains there are 50 hz.
I had to find a small transformer that would work on 60 hz here, and that went ok and the statue worked fine for years. The problem creeped in, which made me wonder if it was a capacitor problem.

The mains frequency almost always makes no difference whatsoever - and certainly not if it's a switch-mode design (as sounds likely).

 

[Sparky12]

Ok, then I am probably in the right neighborhood about capacitor problems possibly, but rather more of a chance that it is in the power supply, rather than the little board that actually controls the blinking itself? I never thought about that, the little transformer I used was on of those selectable voltage kind, that you can select a different voltage by sliding a switch, for different voltages for tape recorders, Walkman’s, or other small consumer items.
Thank you for that tip, I will have to see about getting another one to substitute first, I may have been looking in the wrong place to start then. I appreciate the help!

 

[Les Jones]

Nigel has already told you in post #2 and I agree with him. Check the ESR and value of the main reservoir capacitor in the power supply.

Les.

 

[Nigel Goodwin]

Nigel has already told you in post #2 and I agree with him. Check the ESR and value of the main reservoir capacitor in the power supply.

Les.

Not exactly - I never suggested the reservoir, as that's the least likely to be at fault - they do fail occasionally, but the high frequency capacitors are the ones that are MUCH more likely to fail.

The high voltage capacitors, such as the reservoir, also tend to have quite high ESR anyway, so don't test well on an ESR meter.

But as he's now mentioned that he's powering it from a switchable wallwart, it would be easy just to feed it from a battery to prove if the wallwart is duff or not.