(Topic ID: 301789)

Firepower blowing fuse

By iamdrunker

2 years ago


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04-driverboard.pdf (PDF preview)
FP Schems 2.pdf (PDF preview)
IC Chips.pdf (PDF preview)
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#1 2 years ago

Hello All. I installed this fuse holder a few years back apparently it's doing it's job. When I powerup and in attract mode all is well but when I start a game the fuse blows that feeds the bottom right jet bumper. No switches are closed in test mode. I replaced the diode on the coil last night but still blows the fuse. The only thing that is not working is that jet bumper. Should I replace the coil?
Thanks for your input.
Mike.

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#2 2 years ago
Quoted from iamdrunker:

Should I replace the coil?

First thing I’d do is disconnect the coil and test the resistance. What is the part number of the coil?

Chart with proper resistance of many common coils:
https://www.flippers.com/coil-resistance.html

#3 2 years ago

Here is how that circuit works:
https://pinside.com/pinball/forum/topic/alien-poker-pop-bumper-not-working#post-6534239

(the highlight wouldn't necessarily be for your pop). Likely the activation switch is stuck or something else that feeds the circuit.

The switch test does not show the special solenoid activation switches (they are not part of the switch matrix).

#4 2 years ago
Quoted from YeOldPinPlayer:

First thing I’d do is disconnect the coil and test the resistance. What is the part number of the coil?
Chart with proper resistance of many common coils:
https://www.flippers.com/coil-resistance.html

SG-23-850-DC WILLIAMS REG 5.3 23 850.
I can search about testing a coil but what would be the resistance results when testing a bad coil?

#5 2 years ago
Quoted from iamdrunker:

SG-23-850-DC WILLIAMS REG 5.3 23 850.
I can search about testing a coil but what would be the resistance results when testing a bad coil?

Should be 5.3 ohms according to your quoted text above. Anything less than 4.5 is suspect, zero or nearly zero should blow the fuse immediately. Transistor should be tested as well.

#6 2 years ago
Quoted from YeOldPinPlayer:

Should be 5.3 ohms according to your quoted text above. Anything less than 4.5 is suspect, zero or nearly zero should blow the fuse immediately. Transistor should be tested as well.

I'll check it out.
Thank you.
BTW. What would of happened to the MPU or other components if I hadn't installed the aftermarket fuse holder?
Mike.

#7 2 years ago
Quoted from iamdrunker:

What would of happened to the MPU or other components if I hadn't installed the aftermarket fuse holder?

Should blow the main fuse.

#8 2 years ago
Quoted from YeOldPinPlayer:

Should be 5.3 ohms according to your quoted text above. Anything less than 4.5 is suspect, zero or nearly zero should blow the fuse immediately. Transistor should be tested as well.

Reading 4.0 with everything removed. I guess replace it and eliminate the coil as the issue.

#9 2 years ago

When you replaced the diode, you used a 1N4004 and the banded side towards the double wire power wire? Just something to double-check.

Coil resistance for the pop bumpers on FP around 4 ohms is correct. If it were 2 ohms or less, then that's a problem. My FP pop coils measure at 3.8 ohms with no issues.

Before replacing the coil, check transistor Q8 & Q7 on the driver board for shorts.

20211007_220054 (resized).jpg20211007_220054 (resized).jpgFP-pop-coil (resized).jpgFP-pop-coil (resized).jpgfp-driver-q8 (resized).pngfp-driver-q8 (resized).png
#10 2 years ago

Diode was placed correctly but always a good thing to ask. I will check the transistors in the morning.
Thanks for the input.

#11 2 years ago

It will be a shorted driver transistor not the coil.

Why do people blame the outcome and not the cause?

Coils don't "go bad" - they are just a coil of wire nothing more.

#12 2 years ago
Quoted from pins4u:

It will be a shorted driver transistor not the coil.
Why do people blame the outcome and not the cause?
Coils don't "go bad"

If the coil locks on it can overheat, melt the wire insulation, and pull more current due to the decreased resistance. The fuse should prevent that.

slochar pointed to the explanation of how the circuit works in an earlier post. A failed transistor isn’t the only way a coil can lock on.

#13 2 years ago
Quoted from iamdrunker:

BTW. What would of happened to the MPU or other components if I hadn't installed the aftermarket fuse holder?
Mike.

That is an aftermarket fuse holder which from my understanding, without it, a fire in the wire harness could ensue. Williams design flaw. In these situations I generally use a current limiting light bulb rig that replaces the fuse to see what is happening. In other words, the bulb "shares" the current draw with the coil. If when you turn on the game and the pop is being activated via a shorted switch or a shorted transistor, the bulb will light but limits the current to the coil so it won't burn out. I believe I use a double filament automotive bulb wired in series if memory serves me right.

#14 2 years ago

Q8 is the circuit that is blowing the fuse but Q8 is not shorted to ground. The resistor above it has the same reading as all other resistors. New coil comming just in case.

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#15 2 years ago

Ignore the schematics didn't realize you have a RD in there.

It's still going to have activation chips etc. but if you measured the coil and it's 3.5-6 ohms it's fine. There's 2 chips in the circuit before the predriver/driver (at least on original williams setup) that can be blown and cause the lockon too, so they need to be tested as well.

I seriously doubt that the coil is the issue.

-1
#16 2 years ago

I also have that fuse board in my FP and find that it blows one of those fuses every month or so. It is not the same fuse every time and the pop bumper coils are never locked on either. Spoons are new, gaps properly adjusted and flyback diodes all installed properly.

It is like the pop bumpers draw significantly more than the fuse rating and the fuse "wears out" over time from the stress. I upgraded to 2A and that extends the time between fuse failures but they still happen over time. Has anyone else seen something like this? Installed the same fuse board into a friend's Flash and never saw a fuse blow on that game. Upgraded the solenoid capacitor to 220 uF/160V on the rectifier board to improve flipper strength, that might be a factor... Thanks.

#17 2 years ago

Does the coil lock on when you start a game? If so, check IC7 or IC8:

https://pinside.com/pinball/forum/topic/firepower-locked-coil-at-startup#post-4853936

#18 2 years ago
Quoted from aztarac:

Does the coil lock on when you start a game? If so, check IC7 or IC8:
https://pinside.com/pinball/forum/topic/firepower-locked-coil-at-startup#post-4853936

The fuse blows when I start a game. The coil doesn't lock on but it does a very quick movement and I score a 100 points (From the movement) just before the red hot fuse finally gives up.

#19 2 years ago
Quoted from aztarac:

Does the coil lock on when you start a game? If so, check IC7 or IC8:
https://pinside.com/pinball/forum/topic/firepower-locked-coil-at-startup#post-4853936

BTW, I read your post, I will check it out.
Thanks.

#20 2 years ago

Liftoff to Salt Lake for a few days! Have a great weekend!

#21 2 years ago

My RD board has IC # SN74HCT08N on both IC7 and 8. Looking on Marcos they do not have that exact model number. Is there a cross reference for that chip that Marcos sells? I see that I can get them at other sites but it's handy if Marcos has them. When I get home later today I will test the chips in my board for a short.
Mike.

#22 2 years ago
Quoted from iamdrunker:

My RD board has IC # SN74HCT08N on both IC7 and 8. Looking on Marcos they do not have that exact model number.

The only option from Marcos is this:
https://www.marcospecialties.com/pinball-parts/74LS08

#23 2 years ago

Here are my results, Looks like IC8 could be a bad chip for sure. How does IC7 look with that 3.9?

IC Chips.pdfIC Chips.pdf
#24 2 years ago

Yes - Replace IC8. If you look at the schematics I've attached, Pin 5 on IC8 feeds to pin 4 on the 2J13 connector (Sol 20). Sol 20 is the bottom right jet....

04-driverboard.pdf04-driverboard.pdfFP Schems 2.pdfFP Schems 2.pdf
#25 2 years ago

This was and is a big learning curve. Fun times. Parts ordered. I will update soon.
Thanks everyone.
Mike.

#26 2 years ago

Bench testing the RD board prior to sucking solder I have a new reading of 5.1 on the previous .96 at the IC8 chip. The first test was while the board was installed. axtarac post makes perfect sense and I will follow it but I'm just throwing this out there.

#27 2 years ago

You are far better off buying electronic components from a specialty supplier such as Great Plains Electronics (GPE) or RS Component, Mouser etc etc.

#28 2 years ago

Thanks for the tip. Well taken.

#29 2 years ago

Good Morning all, So, Replace IC8 and still blows fuse so no change there. Cut hot wire from coil 20, replace fuse and start a game. all good, So solder on new coil and let hang before removing old coil. Start a game and blows the fuse. Something is shorting that circuit but only when the coil is attached. I'm thinking running along that circuit the best I can with my continuity tester and find that damn short? Could the issue still be in the board?

#30 2 years ago

If you have connector pins, temporarily run a new wire from the board connector to the coil to rule out whether you have a shorted wire to the coil. Verify the diode is installed correctly on the new coil.

I had a shorted wire that I never found where it was shorted, and ended up running a new wire from the board to the coil. Took a long time, very frustrating, but hey, it still works after four years!

#31 2 years ago
Quoted from Billc479:

If you have connector pins, temporarily run a new wire from the board connector to the coil to rule out whether you have a shorted wire to the coil. Verify the diode is installed correctly on the new coil.
I had a shorted wire that I never found where it was shorted, and ended up running a new wire from the board to the coil. Took a long time, very frustrating, but hey, it still works after four years!

I performed Billc479 suggestion and still blows fuse so the playfield appears to not be the issue. Installed a 2 amp s.b.. takes a bit longer but it to gives in eventually. I mention earlier that the game will add 100 points to the 1st player. After looking at it again, it will score that 100 points then the fuse will start the melting process. Just wanted to make that clear. Tonight's shin dig will be at Space Shuttle. Not a bad backup plan but my looser friends haven't played that machine much. Any other areas I should look?
Mike.

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#32 2 years ago
Quoted from iamdrunker:

I mention earlier that the game will add 100 points to the 1st player. After looking at it again, it will score that 100 points then the fuse will start the melting process

See post 3 and figure out what's causing that pop bumper circuit to lock on.

#33 2 years ago
Quoted from YeOldPinPlayer:

See post 3 and figure out what's causing that pop bumper circuit to lock on.

Does the fact that the pop bumper is not locking on make a difference in your suggestion? And thanks for that suggestion.

#34 2 years ago

Did you verify the diode is installed correctly? How about a pic of the coil with the wires attached.

#35 2 years ago
Quoted from Billc479:

Did you verify the diode is installed correctly? How about a pic of the coil with the wires attached.

Of course not the best solder job.

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#36 2 years ago
Quoted from iamdrunker:

Does the fact that the pop bumper is not locking on make a difference in your suggestion? And thanks for that suggestion.

Maybe. Frankly the thread has gone on so long I can't tell where you're at any more.
I think you said the pop isn't working and the fuse is in the pop circuit and is blowing.
Something in that fused circuit is drawing more current than the fuse can handle, so the fuse is blowing.
It seems likely that whatever is awarding you 100 points is stuck on and is related to your problem.

1 week later
-1
#37 2 years ago

Update, I received my backup Rottendog MPU so with that in hand I installed higher amp fuses. Turned out to stop blowing at 3 amps. I run with that and see what happens.
Thank you for your inputs. Much appreciated.
Now back to Jet Spin's player unit that's driving me crazy.

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#38 2 years ago
Quoted from iamdrunker:

I installed higher amp fuses. Turned out to stop blowing at 3 amps. I run with that and see what happens.

https://nvram.weebly.com/wms-sss.html
1.25 slo-blo is the proper fuse.

Overfusing the circuit isn't solving your problem. It just means you'll burn up something more expensive than a fuse.

#39 2 years ago

I realize it's not correcting the problem. I installed the aftermarket fuse. I know the roll a fuse is engineered to do. I don't know what else to try. I've done everything everybody has suggested. And that's fine. It's fun, It's a hobby. It's not the money. Heck, At this point let it fry something. At least I will know what and where the issue might lie. Then I will post that.

#40 2 years ago

Did you end up replacing the coil? It’s not clear from the thread or pictures.

#41 2 years ago
Quoted from Schwaggs:

Did you end up replacing the coil? It’s not clear from the thread or pictures.

Yes, But ended up reinstalling the old one.

#42 2 years ago
Quoted from iamdrunker:

Yes, But ended up reinstalling the old one.

Why? The lower than normal resistance of the original coil could be what’s drawing the extra current.

#43 2 years ago

The new coil I installed had no affect. I was still blowing the fuse with the new coil installed.

#44 2 years ago

Just a thought is it possible the leg of that diode is making contact with the leaf switch when it fires?

#45 2 years ago

When I installed the new coil I just let it hang off the wires and fired up the game. That's why I never installed it in the game. When the fuse still blew I just removed it and reinstalled the wires to the old, already fully installed coil.

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