Trying to fix some new year lanterns, need a lil assist

[Izlude]

Hi all. I've had this line of chinese new year lanterns (basically christmas lights) for a long time, but then wires have completely deteriorated. They came from a Chinese store back in 2006, real nice set, but they're unusable now  Thought I'd go and cut up some modern christmas lights and rebuild the set by hand. I went and tested them, but 1 side keeps blowing out. I'm certain that I'm not terminating the middle wire correctly. I know nothing about schematics or symbols, so I just drew a crude diagram. Two of the lines have 9 lights each, then there's the middle wire and I'm not sure how to terminate these lines. Might anyone know?

So far, I tried connecting all 3 together at the end, which leads to one side blowing out.  In the drawing, the right line blows out, left side does light up, but none of the bulbs are affected by the blow out of the right line.

There's also the possibility I connected the wrong wires to the controller in the wrong order. I'm almost certain the middle was the line with no lights, could be wrong.. Suggestions?

 

https://imgur.com/a/yfb1OZa  (drawing)

https://imgur.com/a/rozzT2b (the controller and the wires)

Edited January 26, 2025 by Izlude

[ShadeOfBlue]

Are they incandescent bulbs or LEDs? Do you have a photo or information (e.g. part number, voltage) about the actual bulbs themselves?

At the opposite and from the controller, did the original string have a female plug to daisy chain another string of lights?

Do you have a photo of the other side of the controller circuit board?

Edited January 27, 2025 by ShadeOfBlue

[Izlude]

Hi just got back from work. Here's some images and info. It uses incandescent bulbs. There was no female plug on the opposite end of the string, but it did have a female on the back of the main plug itself. The main plug was only 2 wires to begin with, as is the donor. Original plug is 3A 125V, the donor is also 3A 125v with fuses. The capacitor on the board of the controller is 50v 4.7uf.  I have no details about the bulbs themselves, they were all pretty deteriorated anyway. Pulling them out of the sockets left crumbling plastic.

Someone did make a blog post bout a very similar set of lights, but theirs are LEDs while mine are incandescent, and my set only had 18 lights. I might even go as far as to say it's the exact same thing. A schematic is provided.
https://amaldev.blog/christmas-led-light-teardown/

It's too bad I can't see clear enough on their wire config, else I'd have tried to copy it. Anyway, here's mine.

Edited January 27, 2025 by Izlude

[ShadeOfBlue]

That post is indeed very similar to yours. Since yours uses incandescent bulbs, it won't need the inline resistors. And there are some minor differences around the control chip. But other than that, it's essentially the same thing.

Your idea of tying all 3 wires together at the far end is correct. The third wire is just for current to return from the far end. Assuming all the connections are soldered tightly and the bulbs are good, the problem must lie on the controller board.

I would suspect one of the 2 SCRs (black components with 3 leads) next to the outputs. Either that or the controller chip, but there's nothing you can do about that.

When you say one side "blows out", do you mean it just doesn't light (or lights only for a moment)? Or do you mean one or more bulbs gets damaged?

If I were repairing this, I would be probing things with a mutimeter. But, as long as the bulbs are not getting damaged, an easy way to check for a bad SCR is to just swap them (making absolutely sure to place the 3 leads into the correct locations). If the problem also moves to the other side, then you know it's that SCR that is bad. And I'm sure you could find a replacement for it.

[Izlude]

sorry i thought i clicked submit >.<

Well it turns out the board is shot. I might have.. killed it. Apparently the wire without lights (going to the mains) is supposed to be on the far left with the capacitor, not the middle. The other two lines have the 3 prong components (pcr406's), those lines were meant for the lights. Not sure how I missed that. After rearranging them in the right order, nothing turns on anymore. I did manage to locate some of these lights on a Philippines online market called carrousel. I'll see if I can order one of those and this time put the wires in the right spots. Sorry to trouble you  

[ShadeOfBlue]

Well I hope you get something that you are happy with.

You are correct that the return wire should go straight to the plug, while the ones with bulbs should be connected to the SCRs. Having them in the wrong order would cause the current out of one SCR to flow through one string of bulbs, while the current from the other SCR would flow through both strings in series. This would cause bulbs to be on/off/dim at unexpected times, but it shouldn't cause any damage. So that is strange.