I have an old pinball machine. There is a board (PCB) about 4 inches by 3 inches that produces different sounds. This board is not working. On the front of the PCB to the left bottom there is a diode that was blown out (part of it missing) I replaced with another but now if you turn the board over on the right side there was a trace from top to the right most pin, the trace melted. I thought that was the problem and replaced it with a wire but as you can see when I connected it the wire melted. Not sure if it's a capacitor or what the problem is.
The left 2 bottom pins are 26 v AC the next pins (3 & 4) are speaker output and then the 3 pins from the right I assume when you short different combinations of them you get different sounds. The 5th pin in from left
I know a little about electronics. Im thinking that it might be one or two bad capacitors

 

If a track or wire is overheating it means that there is a short circuit on the board.
Remove the wire and measure the resistance between the two points where the wire was connected.

You can also remove the capacitor and measure its resistance. Measure in both directions.

 

@MrChips is right. There's a short circuit somewhere in the circuit. I suspect the capacitor or the transistor-like component.

 

Sorry, my instructions were not correct.

1) With the large white capacitor still in place, measure the resistance across the capacitor, (both directions for each resistance measurement.
2) Remove the capacitor and measure the resistance across the capacitor.
3) Measure the resistance across the two points where the capacitor was connected.

 

I had the large cap out before I saw your post. Anyway it measures 1.5 ohms. I'm thinking the resistance should be alot more for 1000MFD.

 

I had the large cap out before I saw your post. Anyway it measures 1.5 ohms. I'm thinking the resistance should be alot more for 1000MFD.

Go ahead and replace the capacitor.

Still do (3).
(3) Measure the resistance across the two points where the capacitor was connected.

 

Hello,

There are two blue capacitors that do not look well:

Bertus

 

Thanks guys I'll replace all 3 blue ones and the white one. Does it mater if the replacement cap has a larger voltage rating

 

Question about the blue caps. They are all 5uf but there not marked with + or -. The only marking is a grove on the left and goes around the circumference of the cap. I'm assuming that end is neg.

 

Question about the blue caps. They are all 5uf but there not marked with + or -. The only marking is a grove on the left and goes around the circumference of the cap. I'm assuming that end is neg.

No. Don't assume anything.
What is the voltage rating on the capacitor?

 

It says says
5uf
+ 64v +

Also the white cap is MFD is that the same as uf. I googled that mfd is an old measurement. Also does it matter what type like electrolytic or bipolar
Sorry for all the questions

 

It says says
5uf
+ 64v +

Also the white cap is MFD is that the same as uf. I googled that mfd is an old measurement. Also does it matter what type like electrolytic or bipolar
Sorry for all the questions

The large white capacitor is 1000μF/25V. This is a polarized aluminum electrolytic capacitor and are readily available.
I would up the voltage to 35V, 50V or 63V if it fits physically. Note that the lead orientation is axial (not radial).

As far as I can tell from the PCB traces, the small 5μF capacitors are used for timing, as in a mono-stable circuit. A bipolar electrolytic capacitor would be preferred. Even 4.7μF/16V should be enough. They are in a 5V circuit.
I would replace the one white capacitor first and see if the board works.

MFD, mfd are all the same as μF.

 

Thanks for the info. I will order the white cap first.

 

Thanks for the info. I will order the white cap first.

From where are you ordering your parts?
Where are you located?

 

hello

on the bleu capacitors the side with the rim would be the positive side
they are likely old model philips capacitors

bertus

 

The large white capacitor is 1000μF/25V. This is a polarized aluminum electrolytic capacitor and are readily available.
I would up the voltage to 35V, 50V or 63Vif it fits physically. Note that the lead orientation is axial (not radial).

As far as I can tell from the PCB traces, the small 5μF capacitors are used for timing, as in a mono-stable circuit. A bipolar electrolytic capacitor would be preferred. Even 4.7μF/16V should be enough. They are in a 5V circuit.
I would replace the one white capacitor first and see if the board works.

MFD, mfd are all the same as μF.

I assumed you knew it worked on 5v based on the TTL ICs.

 

I'm in Canada, Ontario

 

I'm in Canada, Ontario

Capacitors are not expensive. Shipping is going to cost more than the component.
What city in Ontario? I may be able to recommend a supply store.
Even better, I could give you what you needed if you were near me.

 

I'm in Port Dover or Hamilton or Toronto (Scarborough)
Any of those places

 

Sayal Electronics has 6 locations in Ontario.