Assembled the kit. Attached battery, all LED’s light for about one second, then the outer heart goes off and the inner heart stays lit. Tried several times, left on for a while, same result each time. All soldering looks good, polarities are correct as all LED’s do light for a second. I suspect a bad transistor or bad capacitor.
This is not the first mini-kit I have built, but it is the first one to give me a problem.
Can anyone help identify the problem, and where can I get replacement parts if I need one to fix it?
Most likely assembly problem.
Sorry, this forum does not allow picture uploads
If you can provide LINKS (e.g. by using a free online picture base) to HI-RES and SHARP pics of your assembly (both solder- and component side)
then we can take a look and provide some feedback.
Hi, I am having a similar problem except I don’t believe it is an assembly issue.
Looking at the circuit diagram, it is clear that the left pin of T2 should be connected to the negative terminal of the battery. However, the way the circuitboard is wired is the opposite – the right pin of T2 connects to the battery, and the left pin connects to C2 and R4-7.
Does anyone know which is correct – the circuit diagram or the circuitboard?
Left and right depends on how you hold your transistor and is therefore never used in electronics. We call them by the function of their pens/legs: base, collector or emitter.
Never in my life I had a Velleman pcb that contained an error and also the schematic diagram is ok.
Just follow the mounting instructions and it will work.
Be assured that the PCB is OK, it has been on the market for 15 years now.
Sorry, this forum does not allow picture uploads
If you can provide LINKS (e.g. by using a free online picture base) to HI-RES and SHARP pics of your assembly (both solder- and component side)
then we can take a look and provide some feedback.
Thanks to both of the posters who responded. I will try to re-solder the transistor as well as test it to make sure it was ok.
With regard to the circuit diagram, I am very rusty on my notation but I assume the arrow in the transistor symbol points to the emitter side? If so, then according to the legend in the instructions the emitter corresponds to the left pin of the transistor if you are holding it up with the flat side facing you. This is the pin that connect to the negative battery terminal in the circuit diagram. However, on the PCB it is the right pin (the collector) that is actually wired to the battery.
If my re-soldering does not work I will post a link to a picture as you suggested. Thanks again for the reply and the offer of help – I really appreciate it!
No, that way the emitter is the right pin! I know there are wrong drawings on the internet. Use in doubt always a datasheet from a well known manufacturer.
