This prop replica needs something replaced on its PCB. Any ideas?

[rennervision]

Hello. I have this 25-year-old collectible... bottle(?) - for lack of a better term - that's been giving me some trouble lately.

Inside is a small PCB that powers four Christmas tree lights (via three AA batteries) when you push a button on the front. The way it works is the circuit is complete when the button is NOT pressed. This is a normally closed push button, so pushing it interrupts the circuit, then the button springs back into its default position. This prompts an electronic timer on the board to allow all lights to illuminate for 30 seconds. (The same thing would happen if I replaced the batteries; since I briefly interrupted the circuit, the lights would again activate for 30 seconds.) I assume the 30-second timer is a safety feature so the bulbs don't start to melt the plastic inside.

Anyways, two years ago it stopped working and I was able to find someone online to build a replacement PCB for me. Although I assumed that would be the end of it, now the new board is giving me problems. This time the issue is very intermittent. Sometimes the lights do not shut off after 30 seconds. Two+ minutes will pass and I then have to remove the batteries to turn out the lights.

I’ve also noticed the bottle lighting up on its own. (I didn't press the button.) And then it keeps shutting off and turning back on by itself until I remove the batteries.

I’ve provided some photos of different angles of the components. My apologies as I don’t know much about these electronics, but I'm sure I can swap out anything on the board. Would anyone know which part needs replaced to get it operating reliably again?

Thanks for reading.

 

[Bluejets]

Easy enough to give it a new delay timer module, probably cost around $5 off Ebay etc. for a fully programmable delay timer module with 7 segment LED display onboard.

https://www.ebay.com.au/itm/311908858451

 

[Martaine2005]

The soldering looks terrible. Especially top left corner (yellow wires).
Possibly a reflow with a soldering iron and flux core solder would be all it needs.
Intermittent functionality is exactly what happens when bad solder joints are present.

 

[rennervision]

I could redo that. I see how that could cause the lights to switch on/off by themselves. Would that explain the lights sometimes staying on beyond 30 seconds and not shutting off though?

 

[Delta Prime]

I would reflow pin four (V-ss)

Simple enough after that replace C2 which is a Tantalum Electrolytic capacitor. Whose value I cannot see. And after that the transistor that is hooked up to pin number three.

 

[Delta Prime]

lights sometimes staying on beyond 30 seconds and not shutting off though?

Combination horrible solder connections in conjunction with C2 timing capacitor charges and discharges as you describe the time period of light display .
& the age of the device.

 

[rennervision]

Combination horrible solder connections in conjunction with C2 timing capacitor charges and discharges as you describe the time period of light display .
& the age of the device.

OK. I appreciate the suggestions. Any idea what capacitor I should use if I end up replacing it? Sorry - I'm a little outside my field of knowledge with this.

 

[Delta Prime]

Any idea what capacitor I should use if I end up replacing it? Sorry - I'm a little outside my field of knowledge with this

That's okay no problemo I failed to mention and you caught on that these were steps that are to be taken out first just solder every connection that looks bad then turn your device on & see what happens? The Tantalum capacitor the photo only shows one side there should be numerical markings on the other side and of course third would be the transistor. Although an argument could be made the Tantalum capacitor is highly stable in its ability to hold its capacitance over time and it doesn't look damaged from this side but first things first solder it all up and see what happens. A belated welcome to Maker Pro! Good Night...

 

[Bluejets]

Looks to me like it has already been "attacked" which is why I suggested the $5 replacement....

 

[Delta Prime]

Inside is a small PCB that powers four Christmas tree lights (via three AA batteries)

Show me these four Christmas tree bulbs please... At best , three alkaline double A cells fully charged( 1.6Volts×3 ) would make a battery of 4.8 volts . I'm thinking a grain of wheat incandescent bulb is about to die. I don't want you to dismantle the whole thing only if it's reasonably accessible. Thank You.

 

[rennervision]

Here is a picture I once took of the original PCB with the button and lights still attached. To answer Bluejets' question, the board has to be a specific size to attach to the battery compartment in the photo. (The replacement PCB was created using the same measurements.)

 

[rennervision]

Just wanted to come back in and thank everyone for their help. Looks like the issue was bad soldering. I finally got some time to go over all the spots suggested. (I basically had to redo all the connection points for all the wires and the one pin recommended by Delta Prime.)

The photos helped enhance all the flaws, because the thing is pretty tiny in reality. I wouldn't have noticed them if it wasn't for everyone reviewing the pictures and pointing out the obvious. I've seen some of these sell for $700 when they're in good shape. (Not that I'd ever sell mine, but I'm glad mine is in working condition now.) Thanks again.

 

[Martaine2005]

Glad you sorted it.
A magnifier is a must, even a magnifier app for your phone is better than nothing.