(Topic ID: 220236)

Road Kings blows fuse of kickback / left kicker

By diesel64

11 months ago

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  • 4 posts
  • 2 Pinsiders participating
  • Latest reply 10 months ago by diesel64
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20180630_140859 (resized).jpg
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#1 11 months ago

I have an issue with my Road Kings, blowing the fuse for the solenoids of the kickback (sol. #6) and the upper left kicker (sol. #5C). The fuse blows not instantly, but at seemingly random points during play. So it's not an easy task to debug. This is the fuse which keeps blowing:

20180630_140859 (resized).jpg

Now, I found that Road Kings has a peculiar wiring for both of these solenoids, and it's not documented in the manual. If I understand correctly, these are wired on the flipper power, and not on the normal solenoid power. Maybe the normal solenoid power was not enough for these kickbacks...

They are wired like this: A purple/yellow wire coming from both solenoids, goes via the fuse shown above to pin 15J3-5 on the Flipper Power Supply Board. You can see in the manual that this connection is even erased from the schematic:

road_kings_kickback_wiring (resized).jpg

So where do I start to look for the cause of this issue? Do I need to search on the Flipper Power Supply Board? Is it possible that the bridge rectifier on this board is bad? Any other components to check or replace?

Side note: If I see correctly, I have a 15 amp fuse installed on the Flipper Power Supply Board, whereas the manual says it should be a 5 amp. As I don't trust the manual anymore, can anyone confirm that for Road Kings this actually needs to be a 5 amp? Could this be also an indication that there's something wrong with the flipper power as maybe the privious owner tried to circumvene the problem by installing a 15 amp fuse?

Thanks in advance for any help!

2 weeks later
#2 11 months ago

Bumping this! I have a very similar issue. Both coils are dead, and flippers are dead as well. Good to know they are related. I tested that fuse and remember it being good but after seeing this I'm going to test it again. I will let you know if I discover anything...

#3 11 months ago

So I fixed my issue. It was a weak connector on the flipper power board (lower connector with black/yellow wires coming directly from the transformer).

The 2 high powered solenoids (the kickback and left ramp kickout) are controlled by a relay. The solenoid driver transistors on the CPU activates the relay instead of the coil itself and the high power piggy backing off of the flipper voltage flows to the coil for a hot second before the relay deactivates.

Do you have another flipper power board you can put it and play on for a while to see if the fuse blows? If not I would test the diodes on the flippers and clean the EOS switches. Also, I would change the fuses back to factory specs so as to not damage any other components.

Here's a good walkthrough on testing flippers to check for odd resistances/voltages on the diodes and coils. If something is out of spec it could be the cause, especially since you are experiencing intermittent fuse blowing:

1 week later
#4 10 months ago

Thank you for the reply.

Well, to be fair, I was not 100% complete in my initial post. This machine had other issues, which I assumed to not be related. It had the infamous 3J1 connector on the main power supply which needed to be replaced. I thought this was not related to my kicker fuse issue (as it is on a completely different power rail, coming from a separate transformer winding). But since I replaced that connector, my kicker fuse isn't blowing anymore. Very weird!

Maybe it's all a coincidence and the problem will still return... I have no idea...

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