EBD, memory coil firing at wrong time

[Widnesbernie]

New problem: Every time the pool ball drop targets reset, the memory coil that corresponds to ball 1 & 9 ball also fires.
It is one of the 2 coils with the 3 lugs & 2 diodes on it. Is it possible it is a bad diode or should I be looking elsewhere?

 

[AlanJ]

The 1,9 coil and the outhole kicker coil are controlled by the same circuit, the solenoid expander board under the playfield should be activating to switch between the two of them. Both the 1/9 coil and the outhole kicker coil should have two diodes on them, and they need to be wired up correctly, so that extra diode is in circuit.

 

[AlanJ]

Also check the bulb under playfield that is wired to the solenoid expander board is working.

 

[AlanJ]

All 6 of the coils above use the solenoid expander relay circuit, all 6 of them must have the extra diode on them, otherwise the wrong coils will fire at the wrong time.

 

[Widnesbernie]

The solenoid expander bulb is working. The 1,9 coil is looks like the original coil with 2 diodes.
The outhole kicker coil is an old coil with 1 diode (AN-26-1200). According to the 1981 parts catalogue it should be an AT-26-1200 ( 2 diodes).
I have a replacement coil and diodes for the 1,9 coil (CV-31-2000). I do not have a spare outhole kicker coil AT-26-1200.
I cannot see one of these on pinball mania or pinball heaven. Does anybody know of a suitable equivalent as it will cost an arm and a leg to order just one coil from Marco, 2 with a spare?

 

[AlanJ]

As discussed on the phone, but for anyone else who has similar issue. a diode just needs to be added, to the orange/brown wire. the non banded end of the diode, then the other end of the diode to the coil lug. the black wires remain on the coil

here’s a pic of the outhole coil with two diodes (if you zoom in you can just see them)

 

[stevebm1]

As Alan said it’s pretty easy to add the extra diode to a 2 prong coil,I will see if I can find a picture later when im home from work of how it’s done

 

[Jay Walker]

If you'd prefer an original 2-diode coil, I think the bumper assemblies I saved from an M&M Pac-man have AT-26-1200 coils.

 

[stevebm1]

images as promised,this method involves drilling a small hole in the centre of the plastic between the coil lugs,for the new diode to pass through and in effect become the third centre lug

 

[Widnesbernie]

Thank you all. Really helpful.

 

[Widnesbernie]

If you'd prefer an original 2-diode coil, I think the bumper assemblies I saved from an M&M Pac-man have AT-26-1200 coils.

Thank you for the offer. Going to have a go at adding the diode. I may need to do it again in the future, so I may as well have a go.

 

[Widnesbernie]

Diode added and the 1,9 drop target is now behaving itself.
Still struggling to solder. When I remove some insulation from the original wires they are already oxidised below the insulation.
Is there a good way to clean them?

 

[AlanJ]

solder usually burns the oxide off. or a bit of fine emery paper to take it off.

 

[stevebm1]

tinning the wire before you solder it to the lugs helps as well sometimes