New! Dark mode!

Browsing Pinside at night? Getting tired of all the white? Switch to dark mode using the button in the top right (or CTRL-B)!

(Topic ID: 92219)

Dungeons and Dragons "check FU1 or Field Fuse"

By mshinkle28462

6 years ago

Topic Stats

  • 16 posts
  • 10 Pinsiders participating
  • Latest reply 5 years ago by pinballfan
  • Topic is favorited by 1 Pinsider


Linked Games

#1 6 years ago

I've got a weird problem with a D&D pinball machine, every 4 or 5 plays the game will launch all 3 balls into the trough at some point during the play. Then, usually one or two of them will get stuck in the bottom and the error message "check FU1 or Field Fuse" will display. Upon removing the balls from blocking and turning off and back on the machine, the error message will subside for 4 or 5 more plays. Is this a common issue? If I change the fuse will that solve the issue or is there generally some other underlying problem that causes this to happen that I need to look for as well?

#2 6 years ago

Sounds like power issues to me. Either a poor line off the transformer, bad cable and poor line quality to_ the transformer, or weird voltage sags during gameplay that cause the driver or mpu to drop low enough to think the fuse blew.

Out of curiosity, what do FU1 and the playfield fuses protect? I'm guessing the playfield fuses protect coils, but about FU1?

#3 6 years ago

To be honest, I'm not sure what the FU1 and playfield fuses protect.

#5 6 years ago

I can't find in the manual exactly what it protects, but from my limited ability to read schematics and wiring diagrams it seems to run in line with a diode bridge, a couple of solenoids and a +43V relay. Sorry I'm horrible for info, I'm mostly just trying to compile as much information as I can, so when I do get a repair guy to look at it, it's not just a hodgepodge of troubleshooting.

#6 6 years ago

if it's on the +43V line it protects the solenoids.

check the fuses with your multimeter, both the FU1 and the ones under the playfield .

1 week later
#7 6 years ago

I've checked the fuses and that didn't work, so I took the advice of a repair guy I know and swapped the fuse board with a project D&D I've got and that didn't fix the problem either. Is there anyone else who ran into this same sort of situation?

#8 6 years ago

It's been awhile since I had this game (~20 years) so my memory isn't perfect. When mine had this issue, it turned out to be an issue with the opto boards in the trough. The LED board has black and red (I think) power wires that run up to the CPU board for power. Check to see what voltage you get, and check to see if the IR LEDs are working. If the game is constantly trying to kick out all the balls, it is doing it because the game thinks the balls are still in the trough which is why I think it is the an opto problem. When the game realizes the trough isn't clearing, it assumes(incorrectly) that the eject coil is bad, which is why it tells you to check the solenoid fuses. I hope that helps!

#9 6 years ago

got the check fuse message too. FU1 was blown, replaced it, now it's fine....

1 month later
#11 6 years ago

I am currently having the fu-1 issue, Mine is not kicking the balls but just on start-up, about 6 seconds after the start button is pushed I get the error, Side issue to mine is all the coils fire on power up and stay engaged until the PF fuse blows. I have another thread going on about this issue.

#12 6 years ago

On a side note, I was reading that light shining in thru the opening in the troth can cause the D&D opto to screw up. Apparently if you put something in front of the troth to block the light from leaking in it can help.

2 months later
#13 6 years ago

fu 1 fuse is opto problem.

5 months later
#14 5 years ago

Ok my D&D was working perfectly until I cleaned it today. I put it back together and pressed start. it said it was missing a ball. I could see all 4 balls were in the ball return trough so I manually flipped the last one over to the right where they normally reside. I pressed start again and this time it started with the dragons roar but no music and no ball kicked into the launching trough. There was also no power to the flippers or PF which is normal until a ball is kicked into the launcher trough. After a minute or so the display read check fu1 or field fuse. It seems to be an opto problem but I just can't see anything I might have done to mess it up. I only removed plastics and replaced rubbers

#15 5 years ago

We had the same problem and the (crappy) opto boards in the trough were the cause.


#16 5 years ago

check your lens on your opto with a numerical camera.i found bad lens on mine and fix it.

Promoted items from the Pinside Marketplace
$ 137.00
From: $ 18.00
Apparel - Men
Pinside Shop
$ 19.00
2,800 (OBO)
Machine - For Sale
Austin, TX
Machine - Wanted
Green Bay, WI
1,800 (OBO)
Machine - For Sale
Port St. Lucie, FL
Machine - Wanted
Waltham, MA
$ 10.00
Yorktown Arcade Supply
$ 70.00
Playfield - Plastics
Cobra Amusements
$ 48.00
Playfield - Toys/Add-ons
ModFather Pinball Mods
$ 79.99
Cabinet - Armor And Blades
PinGraffix Pinside Shop
$ 65.00
Playfield - Other
Pin Monk
From: $ 175.00
Playfield - Toys/Add-ons
Pinball Mod Co.
$ 30.99
Lighting - Interactive
Lee's Parts
$ 25.00
Lighting - Led
$ 64.00
Lighting - Under Cabinet
$ 79.99
Cabinet - Armor And Blades
PinGraffix Pinside Shop
$ 28.00
Playfield - Other
Pin Monk
$ 86.95
Cabinet - Shooter Rods
Super Skill Shot Shop
$ 8.50
Lighting - Led
Pinball Haus
$ 48.00
Cabinet - Other
ModFather Pinball Mods
$ 29.00
Cabinet - Other
Filament Printing

Hey there! Got a moment?

Great to see you're enjoying Pinside! Did you know Pinside is able to run thanks to donations from our visitors? Please donate to Pinside, support the site and get anext to your username to show for it! Donate to Pinside