Hi all,

the aux power board on my big guns keeps blowing the 2 am fuses that seem connected to the swivel gate, Bagatelle ball popper and slings on the play field.

I Have tested the swivel gate, slings, and popper coils and all have tested good with no shorts. I have also re soldered the coils as some of the solder looked warn and old etc. I have tested the transistors on the board (TIP 122), by connecting the common lead to ground and placing the other lead in the hole on the top tab, all tested OK.

however the fuses are still blowing. What else should I test? I traced the wires from the coils and haven't found any breaks. I would rather not have to de solder the 8 transistors on the aux power supply board to test them individually but Ill do it if it were necessary. My other thought is that pinballpcb makes a replacement aux power supply board with modern components and i could just replace the whole thing, but I am not sure that this would solve the issue if there is a short somewhere else.

Sorry I meant the 2 amp fuse

there are three of them on the board and all three have blown.
this seems to happen as soon as I turn the machine on.

how would I test that? I am relatively new at this.

Those are the fuses that were in there originally, and the game worked until about two weeks ago when I rebuilt all four flippers. after the rebuild, those fuses blew.(one of the flippers had a coil with one of the copper wires that came lose which has been re soldered) However the flippers are working fine with no issues, but the other three components stopped working. Could be that the wrong fuses were installed, so I will have to check once I get a Schematic.

F1, F2, F3 are the ones that are blowing

OK, I cant see a test point on the board, but that may be just to my inexperience. I am assuming you do this with the pin off but plugged in. I am posting a photo of the board itself. there are scorch marks on the board and the fuse holders, these were already present when I bought the machine and it was working

IMG_0615.JPG

here is a photo with less glare

IMG_0614.JPG

I think I found the problem, after installing some new fuses and turning the machine on, the only fuse that blew was F3. I did some more research F3 also is connected to the coin door and plumb bob. I checked the coin door no shorts however, the plumb bob was pushed up against the ring. My fault I had a box in the bottom of the cabinet that holds all my spare parts and it was pushed up against the plumb bob causing it to stay open. Unfortunately I cant test the machine tonight as I ran out of 2 amp fuses and Radio shack is out of them. So I will see if I can find some at a different radio shack tomorrow and test. I will post once the new fuse it in

Thanks Spybryon,

forgive my ignorance, I am assuming that you are not speaking of a circuit breaker similar to the ones used in home electrical systems, correct? how do you go about using it to troubleshoot and where would you get one, Radio Shack?

Ill be testing the circuit tonight once I get home and some new 2 amp fuses, if F3 still blows I will unplug the connector and see if the fuse still blow. I suspect that it was the plum bob closing the circuit on the ring, but I will find out for sure tonight

Well that didn't fix it so back to the drawing boar. F3 is still blowing as soon as the machine comes on. Ill try disconnecting the connector and try again

Well after spending several more hours last night and this morning tracking shorts from the aux power board to various pin outs, all signs pointed to a short in the drop target on the left of the play field. We noticed that they weren't working. I found the coil in a horrible condition, seems like it may have caught fire at one point and the left lug was missing completely, someone had just soldered a bunch of what appeared to be metal shavings to the coil and the wires were barely soldered on.

the drop target reset appeared to be home made, and the nuts holding the assembly together were long copper post nuts, about an inch long. The sleeve inside the coil was too long and the stop was completely worn and looked like it had burn marks on it. ordered new parts, including coil for right side drop targets, it was bad too. Good Lord, some one did one hell of a Hack job on this.

hopefully this was the issue. keeping fingers crossed

Ok, replaced the two burned coils in the drop targets. the drop targets now work as well as the low under the play field cannon flashers near the slings that weren't working before.

however, I am still having fuse F3 burning and the slings, gate, and king chamber not working. we have traced the schematic for these as well as wiring and here is what we found

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Issue has been found and repaired, transistor Q 79 had shorted out. system is back up and running 100% thanks to everyone that helped with all your advice