Led cherry tree issue

mpeacock

New elf
Joined
Dec 30, 2011
Messages
5
Hi,
We have 4 led cherry trees in our display and our original and favourite stopped working on Monday night. I tried all the usual troubleshooting, swapping out the power supply and testing with the meter before and after the first point after the controller. There did not appear to be sufficient if any voltage coming out of the controller. I cracked the controller and inspected without finding anything visually wrong. The board is a pd-4f1 controller operating with 24vac, if anyone is familiar with them. While measuring some of the voltages the lights on the tree started working. Strange, but it appears that placing the meter probe on one of two contact points seems to have brought the controller to life. The points appear to be off pins 3 & 4 of the chip.
I have unplugged the tree and put it back on display where it’s still working. I’m sure it will fail again, so I’m looking for any insight into what may be going on.
Cheers.
 

AAH

I love blinky lights :)
Community project designer
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Dec 27, 2010
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Eaglehawk
I found https://auschristmaslighting.com/wi...nction-LED-Controllers#Example-10-Uncle-Bills which shows the board type in question. There doesn't seem to be much to see there so it's possible that it could be a dry solder joint. It's also possible that it may have been in some sort of mumble mode and outputting to outputs that aren't physically connected and the probe may have either kicked it out of a latch up or just advanced the mode.
 

mpeacock

New elf
Joined
Dec 30, 2011
Messages
5
Thx Al. Yes I did see the bypass article. That was actually one of the first hits on google. :). I’m going to resolder the joints on the weekend when it’s not so stupidly hot. Photo for reference with circled points that seemed to kick start it. Interestingly, holding the probe on the right circled point keeps the lights on steady mode until released. The tree worked all last night, so will see how it goes tonight.
81D9F2E6-3102-471D-B3D4-2616F6AA5112.jpeg
 
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