NEWBIE -- I have owned pinball machines for only just over a month. I welcome any insight on your approach to diagnosing failures on this old System 6 machine. Thanks in advance!!

My Firepower's behavior has been "deteriorating" before my eyes, and I'm wondering if all the symptoms below, taken as a whole, might suggest a specific problem. I should have time tonight to run in diagnostic mode to check switches and solenoids, but I remain suspicious of board level issues rather than playfield components or connections. I'll eventually pull the playfield and systematically check every solenoid, switch, diode, and solder connection but I'm hoping that this combination of symptoms rings a bell with someone for a simple fix.

(FWIW, the main 40-pin board connector was replaced before I got the machine along with a new Rottendog power supply board. All sounds, lights, displays and game play have generally been okay, except for the growing list of intermittent issues listed below. Yay! Welcome to the hobby!)

I'm wondering if a bad diode or broken diode connection could cause intermittent system-wide misbehavior like this. Could it be a power supply or rectifier issue? Perhaps a bad PIA? Any suggestions are welcome!

New issues since last night. These failures are all intermittent, and can occur or clear up within the same turn:

a. Right flipper intermittently sticks in up position. (After reading some ideas here, I'll check to see if it's something mechanical or electrical. Maybe the EOS switch is getting stuck.)

b. Some switches intermittently fail to register. Lane change can take two or three flipper clicks before changing the lights. Lanes sometimes fail to register, and 1-6 targets don't register but then suddenly work again.

c. Kicker solenoid seems weak, but only sometimes.

Older problems, still unresolved:

d. Solenoid fuse often blows after 20 minutes of play.

e. Intermittent problem with pulsing lights. Discussed here: https://pinside.com/pinball/forum/topic/firepower-lamp-columns-pulse-throb Like the other problems, this occurs and clears up at random.

Hi Purpledrilmonkey.

Thanks for the detailed feedback. Where I said kicker, I meant the slingshot. The lack of power seems like a recent change. The machine had been generally functioning well, except for the lights and fuse, but the other 3 problems all started at the same time last night.

The flipper sticking may very well be due to lack of clearance against the bushing. I recently adjusted the pawl and it might need a proper gap. This popping up yesterday might have just been a coincidence.

The switch and lane change failures are very intermittent as of last night, whereas they previously worked nearly flawlessly. It seems like groups of them fail at once, and then start again just as suddenly. It behaves more like a short somewhere or a circuit issue than the notorious backward contacts.

The fuse that fails is a 3-amp slo-blow. (I believe the original power supply used 2.5 amp, but the Rottendog uses 3-amp.) I have found no rhyme or reason to when it fails other than it becoming more likely to occur the longer I play. The pulsing lights are indeed a mystery that won't be easy to solve. I only mention the lights and fuse because I'm suspicious that all these failures may all be somehow related.

I haven't had time to run diagnostics, so I'll dig into this more in the morning.

Thanks, LyonsRonnie1 and Purpledrilmonkey.

Indeed, I am looking at several separate problems that coincidentally appeared around the same time.

a. Right flipper sticking: Indeed the gap between the flipper and bushing was too small. With a notched credit card I reset the gap. The bushings remain a little sloppy, so I'll order replacements (and rebuild kits). I'm tempted to swap the existing coil springs for the newer external spring style.

b. Switch failures: The right EOS switch and lane change switch have been abused. Closer inspection suggests that they are long overdue for replacement. A previous owner has the leaves looking like crinkle cut potato chips!

The solder point for one leaf of a lane switch was also dangerously close to a GI lighting socket. The "random" loss of a switch column (and/or row?) might be attributed to a direct short to the lights. Play was generally better after I tweaked the position of the leads.

I'm still seeing intermittent switch failures, but now it might be gapping or cleaning issues. I'll need to watch the behavior closely over the next few games. (I'm away from the machine for now.)

c. Sluggish slingshot -- absolutely the result of poorly gapped switches and a sloppy linkage. It's pretty challenging to get them gap close enough for quick response but far enough to avoid re-firing the solenoid. The two switches were gapped differently, so behavior was radically different depending upon which switch was closest to the ball.

d. Solenoid fuse: It's still hard to say what's happening here. I blew one fuse after about 30 minutes of diagnostics and test play. The next one lasted for less than 5 minutes of game play. I should have inspected the system for hot components. Maybe I can borrow my coworker's thermal imaging camera...

e. Pulsing lights: Still clueless.

For my own peace of mind, I think I'll ultimately redo the 40-pin connectors myself. Everything I've read talks about the horrors induced by bad connections there. Meanwhile, I'll try the gentle flexing test to see if it triggers any failures.

The previous owner suggested that the owner prior to him was a bit of a hack. Despite the clean up work done before I got it, I still find evidence of sloppy work under the playfield. Regardless, the game generally plays very well. I'm not sure if I'm up for completely disassembling and restoring the system, but I'll likely begin systematically servicing a couple components at a time. I'll probably begin de-/re-soldering, testing, cleaning and replacing the sleeves and diodes on each solenoid.

Hi, Keetur. Congrats on getting your new (old) machine! This forum is priceless for maintaining and troubleshooting your system. I'd like to think I too can fix anything, but inevitably nothing is as easy as it sounds and it always takes three times longer than you'd expect.

I'm still dealing with intermittent switch failures. I've ruled out cleaning/gapping the switches -- they respond beautifully. Rather, it seems that occasionally the system fails to scan, or delays scanning the switch matrix. The best example of the failure would be the ball landing in a multi-ball lane, or going down the drain, and sitting there for at least half a second before the machine responds with score or kicker. Most of the time, when working correctly, this is instantaneous. Similarly, any/all rollovers and standing targets will sometimes fail at the same time to respond, but act fine moments later.

As discussed in many, many threads, the 40-pin main board connector is always a suspect. Mine was supposedly redone by the previous owner and all solder points checked by a local shop when the power supply was replaced. However, I may need to pull the boards and check them again, because I need to be 100% certain this isn't related to the intermittent failures.

More status and general rambling about my recent observations.

To Vid1900, regarding intermittent issues: Thanks, the main connectors seem to be all bright white and shiny silver. But you're right about tail-chasing. I need to be smart about systematically eliminating issues here. I have not yet removed any boards from the backbox for detailed inspection. (Where does the time go?)

Regarding my item "d" above -- the solenoid fuse blowing: Specifically troubleshooting this issue last night, I found that with the backbox open, the fuse seemed to last longer -- well over 30 minutes. After closing the backbox, it failed within 5 minutes. I'm going to stick my meter's thermocouple in the backbox to see just how hot it's getting in there. (If there are bad solder joints as suggested by LionsRonnie1 above, I'm sure that high temperatures would only exacerbate the problem.)

Related to this, would I noticeably lower the backbox temperature by switching all the bulbs from #44 to #47?

Regarding item "b" above -- the intermittent switches: This remains the single most frustrating issue. I really don't think this is mechanical or bad soldering, as the switches previously all worked flawlessly. They currently seem to cycle in and out over the course of a few seconds... all working, none working, all working, none working... just wait an instant and the switch fires the next time you hit it. (As I describe it, I realize that this sounds strangely similar to the pulsing lights problem I also see from time to time.)

I continue to watch the system deteriorate before my eyes... Yesterday I detected a drop in audio fidelity. That rich, memorable firepower sound has become "tinny" like listening to a small transistor radio. I adjusted the effects balance and main volume, but these don't change the audio quality. One more item to research and restore. (Sigh.)

I don't have a test bench set up yet, nor a lot of electronics experience. I have a decent multimeter, but no logic probe, scope or tracer. I'll start some clean threads later with more specific questions about testing specific components, unless of course I find it already in an earlier forum thread.

Thanks, everyone for allowing me to ramble on about this. Hopefully, as I continue to nibble away at the troubleshooting, I'll get more clues to share with the experts here.

Vid1900: Thanks for "vids-guides-to-everything". These are excellent resources for newbies and veterans alike. I appreciate having them available here.

LyonsRonnie1: I keep a crisp new bill in the coin tray for cleaning the contacts. The failures are new, and too intermittent to be dirty contacts. I keep them clean and test continuity frequently. I think you're right about bad solder joints, and they are at the top of my never-ending "TO DO" list.

Mof: Thanks for pointing me at the club. I hadn't noticed before, but count me in! I'm about 1/10th through the old posts there...

Who's going to Pin A Gogo?

vid1900: Regarding the "bullet proofing" -- Wow. Awesome stuff. This should keep me busy for a while. I love the swap of MOSFETs for TIPs -- anything to reduce temp is a good thing.

Don_C: I think the previous owner already took care of the Combo ROM upgrade. He worked with a reputable shop in the area, so a lot of this has been done already.

I'll need to make time to do my own assessment of just about everything in the system. I'll post photos and a list of my observations here over the duration of the restoration project.

Instead of eating dinner tonight, I spent hours inspecting and photographing the boards and bottom of the playfield.

Started inspecting per the Bulletproofing guide:
- I do not yet have fuses as recommended off the rectifiers for fire prevention.
- TIPs have not yet been replaced with MOSFETs, and the old resistors are discolored from the heat. It's time to make the switch to MOSFET and Zero ohm jumpers.
- The 40-pin connector was replaced recently and still looks awesome. I'm not worried about it. However...
- All the other connectors are wiggly and loose. After my inspection, neither the score display nor solenoids 1-8 worked. The solenoids were particularly hard to get working. Reseating all the plugs eventually fixed both problems, but this indicates that I need to spend some time replacing ALL the molex connectors and pins.
- I found and fixed another potential short between a switch and the GI wiring.
- I tested all solenoids (in line) and found them each to have a resistance of about 4 ohms.

Coin Door Lockout:
All the other solenoids tested as 4 ohms, but the coin door lockout coil showed a resistance of 262 ohms. Could this be contributing to the blown solenoid fuses?

Power supply question:
From the Rottendog power supply, I tested the voltage of the red solenoid power wires at 35V. The original schematic shows solenoids powered at 28V. Could this be contributing to the blown fuses?

I've removed a lead from the coin lockout coil. I was really hoping that this was the source of the blown fuses, but no. I blew another one after about 20 minutes of play. Oh well, troubleshooting continues...

(Good news -- knock on wood -- the intermittent switch failures and pulsing lamps are gone. Game play is rock solid again. I'm afraid to touch anything for now! I'll enjoy it for a bit before diving into "bullet-proofing" mode.)

mof, your link didn't point at a product. I assume you were going to suggest a circuit breaker? I have a 3 AMP thermal circuit breaker I was going to solder to a blown fuse and drop into the socket for troubleshooting.

mwsmith, yes, I'm using 3A slow blow as recommended for this board. It takes about 20 minutes to get to the point where the system goes nuts and all solenoids fire. The scoreboard displays flash crazy numbers at the moment of failure too.

I'm gonna switch to #47 bulbs in the back box and make pin1900's suggested change of TIP to MOSFET and get rid of the hot resistors. Hopefully keeping the temperatures down will help. I'll also recheck all the solder points for cracks or cold joints.

Thanks Archieball. If nothing else I'm learning that there are few coincidences in electronics. If things start failing at once, they are probably related, regardless how unrelated they seem. My "random" switch failures had to do with a missing staple on my braided GI wire. When the playfield was up for work, it all looked good, but when horizontal it would sometimes short against a switch. I fixed this and the machine plays better than ever.

Regarding the solenlid fuse, I've not seen any pattern to the failures. I recall it failing at least once while sitting in attract mode. The game generally does not lock up, but sometimes does. Flippers and sounds remain active (unless I'm imagining things.) I'll try to capture the failure on video. In additon to checking solder points, I will start replacing diodes.