Whitestar T3 - Flipper Fuse Blows When Button Held

[retroactive85]

Hello again Canadian friends!

I am troubleshooting my Stern T3(Whitestar) and am having a flipper issue. The game flips fine otherwise and seems to have no issues with the flippers during normal play. However during multiball or anytime you'd hold the flipper up for 5-10 seconds, the flipper fuse will blow. Replacing the fuse and powering the game back up resumes play as normal until inevitably it happens again. Sometimes I'll play 10 games and have no issue, but it always seems to blow when I'm holding that flipper up during a multiball.

Problem:
Play game >> Hold Flipper up for 5-10 seconds >> Fuse Blows >> Replace Fuse >> Play game >> etc etc

I'm reading that when a flipper locks on and fuse blows at powerup it's likely the transistor shorted(like my LOTR magnet issue I posted about). However in this scenario where it's somewhat intermittent I haven't been able to nail down an exact cause for the fuse blowing. I'm thinking that somehow it's not flipping over to the "hold" voltage at EOS. Anyone have any suggestions on some test points to track this issue down?

 

[Menace]

Bad or broken EOS switch / wire would be where I would start. The game is not recognizing the flipper is being held up and cutting the high power so it's blowing the fuse after a small period of time. Easiest way of checking the eos switch is put the game into switch test and manually raise each flipper with your hand and you should hear the sound for a closed switch indicating the MPU detected the EOS closure. Do that for all of the flippers and I'm guessing the flipper that blows the fuse will not register the EOS closure.

Once you've confirmed that, you can then begin to look things over starting at the EOS and work your way back.

D

 

[retroactive85]

Thanks, I briefly thought of that then read somewhere that hold power was handled by the CPU instead of the EOS switches in modern games.

I'll give them a test, looks like EOS are under the "dedicated switches", left is #2 and right is #4. They are "normally closed" according to the manual.

 

[Menace]

I have seen some games with busted EOS switches where a previous "tech" hacked them so the game thought they were always closed and always had the high power active.

D

 

[retroactive85]

I tested both EOS switches in switch test. Both test fully closed at rest, and open at the same point in the stroke. Also tested both flipper buttons to make sure they made constant contact when pressed, and didn't lose contact intermittently. I'd think the EOS switch is not the issue.

What to check next? Is it possible that the Q15 transistor for the left flipper is going bad? Do transistors have an in-between bad state, or do they go directly from working to fully bad/shorted? I do have a spare IRL540N transistor on hand, but I don't want to jump to conclusions and just replace it.

 

[Menace]

Nope, the MosFET that drives that flipper either works or doesn't.

So you confirmed in switch test that the EOS switches are both working correctly electrically? Just because they look like they are mechanically working correctly doesn't' mean the MPU is receiving the correct information from them.

If you've done the above and confirmed the EOS switch is being sensed correctly I would check the resistance of the coil on the flipper that is blowing the fuse and compare it to the resistance of the flipper that doesn't blow the fuse.

D

 

[retroactive85]

Yes indeed, I tested both flippers in switch test and saw nothing to make me believe the switches weren't working correctly.

I was curious if maybe the coil was the issue. I found a few threads on testing the coils, worth a shot. Since the problem is so intermittent, makes me wonder if a "bad coil" will show up on a multimeter test but we'll see.

 

[Menace]

When you say you tested the flippers in switch test, did you just flip the flipper with the flipper button or take the glass off and manually move the flipper bats to the up position with your hand and check for EOS activation?

And how intermittent is the issue? It sounded originally like this happened every time you held the flipper up for more than 5-10 seconds?

D

 

[retroactive85]

I manually moved the flippers to the up position and watched the screen for activation. Normally they are closed, when the flipper reached end of stroke it showed as open in switch test.

I mentioned in my first post that I can play 5 to 10 games and not have an issue. I even tried holding that flipper up for 20 seconds and flipping it rapidly but the fuse didn't blow. It seems each time it has happened it has been during multiball. I know at least two of the three fuses blew when cradling a ball on the left flipper for a few seconds. I don't want to keep blowing fuses so I haven't tried again. I've been through 3 fuses, I have 2 left. Going to buy more of course.

 

[Menace]

Is it the flipper fuse under the PF that's blowing just for that flipper, or is it a fuse on the driver that supplies power to other PF coils that's blowing?

D

 

[retroactive85]

That's a very good question, and I meant to mention that. It's the fuse under the playfield right by the flipper. Replacing it with the specified 3 Amp Slow Blow fuse.

 

[Menace]

Ok, so it's just that flipper fuse then. I would check the resistance of that flipper coil and then and compare it to the one that doesn't blow the fuse. If they have the same part# and they measure vastly different I would look into swapping in a new coil.

Start there and keep it simple.

D

 

[retroactive85]

Sounds good, I'll test both coils with my meter in a few hours after work and compare.

I'm stoked to get this T3 100%, I picked it up HUO for a very nice price and it's been on my wish list for a while. I've done rubbers, bulbs, balls, and a thorough cleaning. Looks like a new game, just has to play like one

 

[retroactive85]

Well I tested both coils and they read the exact same in the ohm test at 11.

I looked around for anything obvious that would be randomly shorting it but didn't see anything around the flipper mechs of concern.

 

[retroactive85]

I just played 5 games with numerous multiballs including one grand champ score hitting the wizard mode. Held in the flippers, hit them rapidly, etc and no blown fuse. Who knows... had fun at least!

 

[Menace]

I hope this isn't a stupid question, but the fuses you were using originally were 3A slow blow right?

D

 

[retroactive85]

No worries. Yes, they all came from the same Bussman MDL3 case. The original fuse in there was the correct value as well. I'm at a loss as to what would randomly blow the flipper fuse 3 times if not the coil or the transistor. Guess I'll report back in if/when it blows the next time. Would love to narrow down the culprit if i can but at least the game works and plays well in the mean time.

 

[Menace]

Yep, intermittent issues are a royal pain to troubleshoot. Glad to hear it's at least working good now.

D

 

[retroactive85]

Bummer, I'm back! Went through two fuses in the last two weeks. Played roughly 30 games in that time period. I replaced the Q15 transistor with an IRL540N today and thought perhaps I had solved the problem until it blew again. Oh well at least I have the more robust transistor installed now.

I am suspecting now that the problem lies with the coil/diode. I plan on replacing one or both in the coming week - but I'm out of fuses so I have to wait til I get my Pinball Life package in the mail.

 

[retroactive85]

I clipped the diode on that coil and tested it. It tested the same as the replacement diode I have for it. Is it possible that the diode is still the culprit? Do they intermittently go bad? Also if a coil diode goes bad, wouldn't it blow the transistor, not the fuse? I'm confused!!