Maverick flippers machine gunning

[paddythegreek]

Just gone to play Maverick and the left flipper is machine gunning as is the lower right. The upper right energises then drops back. Whilst this is happening the led's on the flipper board are flashing on and off. The eos are new and set correctly. The flipper board is a rotten dog one but looks like its had some transistors changed at some point. I don't have a schematic for the rotten dog board either. Thanks Ken
Just to add. Left machine on in game play for 5 mins and now both right flippers are working perfect. Left is still bad

 

[PinballDaze]

Clean switch contacts on LH flipper cabinet button.

 

[paddythegreek]

Nope thats not it. The cab switches look new anyway but i did clean them

 

[PinballDaze]

Does the led stay lit when the button is held in?

 

[paddythegreek]

Nope just flashes

 

[PinballDaze]

Use a shorting lead and short out the switch.

 

[paddythegreek]

Not made any difference at all. Seems to point to the flipper board to me

 

[PinballDaze]

Have you removed the flipper board and checked fuse clips?

 

[paddythegreek]

Did that earlier whilst checking for dry joints. Thats how i found someone had repaired the board

 

[carl lawrence]

Silly question time !!
Will it do it with the Playfield in the up position ?
Just thinking is there a short down the line somewhere !

 

[paddythegreek]

Dont think its a silly question not when we're dealing with damn pinballs
Yes it's just the same, up/midway or flat

 

[PinballDaze]

Board. Transistor on heatsink. Had one stuck on, but not gunning though.

 

[carl lawrence]

Was it doing it before the new eos switches installed ?

Just clutching straws sorry

 

[paddythegreek]

I didnt install the new eos, there were there when i bought it and its been working fine.
One thought, dont DE use a one shot flipper system. Could it be the fact that the led's are flashing on the flipper board cos the board is repeatedly firing one shot making the flippers machine gun?
If so is it the ic that creates the one shot.

 

[cooldan]

I thought machine gunning flippers often meant a bad coil. Have you tried swapping them out?

 

[paddythegreek]

Tbh no as the coils have only one winding and the all read virtually the same ohms on my dmm.
Have yet to go and try it today

 

[paddythegreek]

Just tried it. Both right are working as they should. Left is gunning

 

[cooldan]

what happens if you move the right ones to the left, does to problem move?

 

[paddythegreek]

I take it you mean the coils. No haven't swopped them over but it now might be tomorrow as forced to go visiting family.

 

[carl lawrence]

what happens if you move the right ones to the left, does to problem move?

Or the right coil cables to left so left operates right and right operates left !

 

[paddythegreek]

Update. Having installed a working DE board courtesy of Dave @ pinballdaze everything now works perfect. Bits on order to repair the Rottondog one.
Thanks for everyones advice and help.

 

[carl lawrence]

Out of interest what parts had malfunctioned on the board ?

 

[paddythegreek]

The U2 chip 74HC4538.
Q8 IRF9530N mosfet
D2 a 4004 diode and R29 a 4K7 resistor

 

[carl lawrence]

The U2 chip 74HC4538.
Q8 IRF9530N mosfet
D2 a 4004 diode and R29 a 4K7 resistor

The U2 chip as well ,not good

 

[paddythegreek]

Yea well i held my finger on the button deliberatly as it was gunning to see what would happen. The bits i had to replace today was the end result although something caused it to machine gun in the first place. All now working as of 1pm today.