Sign me up! My favorite era of pinball. Just picked up a #fire, but hope to get more in the future. There was a great thread for system 11 mods and other things that should be replaced/done as soon as you get a system 11, but now I can't find it!!! Anyone know what I'm talking about?

Hey guys, I was going over the flippers on this Fire! pinball and noticed that the right flipper is missing the yellow capacitor. Game plays normally, just wondering if it should be there (i think so?), and what the purpose of those capacitors is generally.

My Fire! pinball has been making this high freq capacitor squeal noise for a while now. The first time I noticed it was before I had done any work in the backbox, and I figured once I replaced all the caps it would go away. It hasn't! It's intermittent and tends to go away once it's warmed up. I changed all the caps on the power supply, save for one, which either wasn't listed in the kit (I had to part it out because the kit was unavailable) or I missed it. It's located in the lower right corner of the p. supply board and is physically quite small, although I don't recall the value. I also replaced the big can cap and rectifiers with the nice fused replacement board.

I can follow the sound with my ear, and it's definitely coming from the power supply. I'm wondering if any of you have had any experience with something like this?

I will double check those caps when I get a chance, also thanks for designing that board, it made things very easy!

Nope it's all original!

Here's the power supply. I checked that I put all the caps in the right direction. The only one I haven't changed is the little guy in the lower right, between the relay and the heat sync.

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I will feel kind of stupid for posting if it does in fact turn out to be bad and causing the problem. I followed the sound with my ear and it seemed to be coming from the area around the big caps, but with a high freq noise like that it can be tricky to pinpoint with your ear. Should probably have just changed it to begin with! I will check when I get home tonight if pulling that fuse stops the noise.

I was able to stop home on my lunch break, and confirmed that pulling f1 does stop the squealing. I'll change C8 in the next few days and let you all know if that fixed it.

So over the Christmas break I was able to change C8, I went ahead and changed C7 as well, just because I wasn't positive I had changed it last time. Hooked it up last night, and it's still singing! So onto the next thing!

Do you think I should change Br1? Seems like the only bridge on the P-supply board. I have a few KBPC3504-W's laying around. That's a 35a 400v bridge, would that work as a replacement?

I will do that! the +/- 100v is used for the display correct? Might be worth mentioning that I replaced the original displays with a pinscore board, the noise was there before I swapped that though. Also, not sure if I mentioned it earlier but the noise usually goes away if the game is on for a little while. Anyway, I will take a look at the high voltage circuits and see what I can find, thanks a lot for your continued help!

There are a few different brands of caps in there, I used the autozone method, which is to say, I didn't buy the cheapest caps I could find, but I also wasn't buying the most expensive. Some I didn't have much choice as there were only a handful available in that certain value or style. The noise does not seem to fluctuate with the display being lit, I do however have some noise coming through the speakers that seems to change with the display. I think this is usually a ground problem on the sound board, I'll have to clean up those screw terminals nice, but it doesn't really bother me all that much.

I did some poking around in the high voltage section of the power supply, the 100v measured at 99v which I think is within spec, I didn't really find anything else glaringly wrong here, I did clean up some solder joints and stuff, but the issue persisted. So, for now, I've just pulled fuse F1, not the greatest solution, but since I've updated my display there is nothing else that uses that voltage anyway. I play tested the game just to be sure of that, and yeah, everything plays normally.

Thanks again to all of you who were giving me suggestions, I appreciate it a lot.