Zaccaria Flipper flutter

[robm]

I'm helping a guy out with a Zac Star's Phoenix.  He got two new lower flipper coils (the old ones were weak) and the upper flipper never worked (or was locked on - he's a bit hazy on the details), so he put one of the lower flipper coils in the upper flipper position (different coil no.).

Then he turned the machine on, upper flipper locked on, lower left flipper fluttered, then blew F5 fuse.

Then he pulled out upper flipper coil, joined wires to complete circuit, and the lower flippers both worked fine, although F5 still blows after 10 secs or so of playing.

So... i've got the driver and power supply board here, and found one locked on transistor Q8 which works the left ramp diverter.

What i can't find in the manual is what drives the actual flippers themselves.

Also, what is the flutter a symptom of?

I tested the lower left flipper coil, and the resistance seems to jump around between 0.2 and 3 Ohms - could not get a consistent reading, so i am thinking the coil might have a short or bad diode (unusual as it was just bought new from Marco Spec) - i did not have time to pull the wires off or one end of the diode to test properly.  But doing a continuity test of the EOS (NC), it reads always closed, even when open - so again i'm thinking this would indicate a shorted coil.

Any other ideas or pointers, particularly how to test the flipper drive transistors wherever they are?

[Homepin]

Looking at the schematic - assuming I have the right one - it seems as though the flippers have no driver transistors, there seems to be two flipper relays that switch the  +39VDC but that's seems to be it???

[Retropin]

Looking at the schematic - assuming I have the right one - it seems as though the flippers have no driver transistors, there seems to be two flipper relays that switch the  +39VDC but that's seems to be it???

Correct - no transistors, flippers are run to ground via the FLIPPER ENABLE relays

[robm]

So i assume these are the relay's on the power supply board? (There are two)

So its probably not a flaky transistor causing the flutter, but the EOS or coil short problem?

[Retropin]

Yes - upper flipper coil could well be duff.
Fuse blowing more than likely the locked on transistor... check associated coil for this also as this will be energised while transistor is locked on.
Is transistor faulty or switch for coil permanantly closed?

[robm]

Yeah its the transistor  - the centre tab buzzes to GND on the board, when the rest don't.

Will replace the transistor (read that these can be replaced with a TIP102 instead of the original BDW93c), and also the flipper coil and double check the EOS

[Homepin]

I would say a TIP102 should be fine.

BDW93C - 100V 12A NPN Darlington - pinout BCE

TIP102 - 100V 8/15A NPN Darlington  - pinout BCE

It should drop straight in with no leg swapping.