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(Topic ID: 150279)

SOLVED: First Ball Relay Buzz on 76 Royal Flush

By MrWizzo

4 years ago

Topic Stats

  • 4 posts
  • 3 Pinsiders participating
  • Latest reply 4 months ago by Jerry208
  • No one calls this topic a favorite


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#1 4 years ago

Done all that I know to do:

-installed new spring;
-decreased tension on old armature spring;
-straightened switch leafs and adjusted for minimal tension;
-switched armature with no wear from a non-hold relay;
-measured resistance of coil, 22.3 ohms
(Pinrepair gives a 9740 coil 24 ohms);
-all 9740 coils measured 22+/-;
-set transformer back to normal tap.

Are 2 ohms less resistence enough to be the cause?

Going to find a 9740 coil from another game that meets the 24 ohm resistence and see if that changes anything.

Anything I missed? Thanks.


#2 4 years ago

Thanks to Flippy on RGP. He suggested checking for the copper washer at the coil screw. It was missing.

Posting this for future reference. Installing the washer quieted the buzz and it required tweaking the switch contacts.

#3 4 years ago

Those washers are brass, not copper. They're used to isolate the magnetic field when the coil is energized, and are needed on all the relays mounted that way. (The newer replacement relays have plastic ends on them, so then the washer isn't needed.)

4 years later
#4 4 months ago

I just bought a Royal Flush and the 1st ball relay buzzes and the coil gets hot. Looking at the schematic I found that the relay coil should be an A-9740 (22 Ohms), the coil that is in the machine is an A-489 (15 Ohms). I'm ordering an A-9740 coil. We'll see if that quiets it down.

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