Williams SS Help Black Knight (Williams, 1980) Spongy Flipper

[lothian]

Much has been written about various flipper coil issues within this forum and others. The consensus among those knowledgeable of technical pinball stuff seems to be that poor flipper performance typically indicates a problem with something upstream in the circuit because coils rarely go bad and never get weak. Fine.

So what causes a spongy flipper? I've got one. When a ball smacks a flipper in the up position (cabinet button depressed) the thing curtseys noticeably before bouncing back up. When I push on this flipper in the up position it genuinely feels spongy.

I'm definitely new to working under a pinball playfield, so I have zero ability to recognize "ah HA!" I checked the usual list of mechanical whatnots and none are the cause. The coil is getting 25v but I think it's supposed to be 28v; high and low winding resistance values are in spec. Could lower-than-required voltage would make a coil weak? Would three volts make that much difference? Do I need to investigate the driver board? Is there a mechanical issue I've over-looked...

 

[Isaac Sauvage]

The consensus among those knowledgeable of technical pinball stuff seems to be that poor flipper performance typically indicates a problem with something upstream in the circuit because coils rarely go bad and never get weak. Fine.

Could it be that's something which applies moreso to modern-built coils in SS machines than older coils in EM's?

So it's been decades now, but from what I recall working on some EM's I once owned, replacing the coil certainly perked up the flipper. At the same time, not surprisingly at all if coil performance is also impacted by fading power supply, and maybe, failing solder connections & old capacitors?

@Pop Bumper Pete, @pinballdaveh,
Any thoughts on this stuff?

 

[pinballdaveh]

Could it be that's something which applies moreso to modern-built coils in SS machines than older coils in EM's?

So it's been decades now, but from what I recall working on some EM's I once owned, replacing the coil certainly perked up the flipper. At the same time, not surprisingly at all if coil performance is also impacted by fading power supply, and maybe, failing solder connections & old capacitors?

@Pop Bumper Pete, @pinballdaveh,
Any thoughts on this stuff?

The most common cause of spongy flippers is that the Bakelite or fiber link gets elongated holes from use and are hard to spot. To test flipper link slop, with one hand hold the metal part of the flipper coil plunger and with the hand try moving the flipper back and forth. Replace link if slop is excessive.

 

[lothian]

Linkage is tight. Additionally, plunger is not abraded, the end is perfect, and it slips effortlessly within the sleeve. The stop shows no damage. The only thing that seems peculiar is that voltage thing.

 

[pinballdaveh]

Linkage is tight. Additionally, plunger is not abraded, the end is perfect, and it slips effortlessly within the sleeve. The stop shows no damage. The only thing that seems peculiar is that voltage thing.

A voltage loss is usually a weak connection.
The flipper enable relay might have a voltage loss on it’s switches . Inspect male pin circuit board connections for cracks and check female connectors for loose wires. Also check the interconnect plugs between the body and head.

 

[Pop Bumper Pete]

When you engage a flipper, two coils come on, a strong one to move the flipper, and a weak one to hold it up

lift up your playfield and look at the mechanism (with the game off)
Move the flipper with your hand, you will notice that when the flipper is in the up position, it will open a switch. The gap in the switch is too wide, it only needs to open a little bit

Oh, it helps to tell us the name of the game

 

[xenonph]

Oh, it helps to tell us the name of the game

I believe the machine they are talking about is Black Knight, as they posted Flipper Problems post not long ago.

Williams - SS - Black Knight (Williams, 1980) Flipper Flutter

Black Knight 1980 The right lower-playfield flipper on my BK80 has begun to flutter when both upper and lower flippers are "up". Flutter does not occur when I close the lower-playfield flipper contact or when I close the upper-playfield flipper contact—flutter only occurs when I close both...

pinballnirvana.com

I updated this posts Title to include Black Knight.