Data east auto launch coil

[Wintonmartin]

Morning

I had a burnt out coil that was blowing a fuse on start up. I replaced it with what I thought was the correct part type but I fried the coil. Soon realised I read the wrong schematic, and now have the correct type (I won't be making that mistake again)

My questions are. Would different types of coils blow the fuse on start up and why? Resistance of the coil? Wouldn't it only fire when triggered? I don't want to connect it up and fry a completely good coil.

When disconnected the game plays fine and no sticking switch etc.
Wrong coil 23-800
Right coil 24-940

TIA

 

[paddythegreek]

Coil resistance wouldn’t make any difference apart from being weaker or stronger than the correct coil. I should say the burnt coil has taken out the drive transistor which has created a short hence the fuse blows. It’s gonna play fine with the new coil disconnected. It’s when you connect it up that it’ll blow the fuse. Change the relavant transistor and small pre drive one as well.

 

[pinballmania]

What paddy said.

 

[pinballmania]

It’ll be one of the TIP36C on the lower left circuit board. Often the transistor before that (TIP102 on the cpu) is ok, and can be left as it’s much harder to swap out than the TIP36C.

Be sure to connect the coil the right way round with respect to the coil mounted diode. If it’s reversed it’ll short then diode and take out the transistor.

The larger of the wires should be connected to the banded end of the diode.

 

[Wintonmartin]

Thanks gents

I'll get the board out and give it a test then get some more bits ordered.

Is the pre drive transistor TIP102?

 

[Jay Walker]

Hello,

The TIP 102 is the 'driver' device, the pre-driver is a smaller transistor, without the metal heat sink/tab. The 102 can cope with some coils on its own, with the additional 3rd stage of a TIP 36C it becomes a controller rather than the actual coil driver

An example of this is a Jokerz that I dealt with at work, or rather at a location. The r/h slingshot was disconnected, due to it locking On, as I found on re-connecting it. I pulled out the Cpu board and changed the 102 driver, but it still locked On. This was how I learnt that a 3rd stage existed (the TIP 36C), on what Williams called 'Aux Power Driver Board'.

 

[Wintonmartin]

I'm also calling it an auto launch but its a VUK.

The schematics show it as 23-800 but the assembly shows a 24-940. The other VUK is a 24-940. That's what confused me initially. Is that a misprint?

 

[Wintonmartin]

Faulty transistor. Will get it changed and hope it works.

Thanks

 

[Jay Walker]

It isn't only Williams manuals that give confusing information, then.

As a rule, the 24-940 (940 turns of 24 gauge wire) should be less powerful than a 23-800 due to its higher resistance. Though as its for a 'super' vuk which may be quite tall, the 23-800 may be right. It would fit with needing a 3rd stage driver, too. There's no harm in trying the 24-940 first, though if it struggles to throw the ball up/out it could overheat from repeated attempts

 

[Wintonmartin]

They're both the same size dimensions wise. The other VUK fires it higher onto the mini playfield so assuming it will be enough as its only a scoop.
The old one was melted to bits but I still have it. Is it possible to tell the gauge of the wire by looking at it?

 

[Jay Walker]

If there isn't much 'throw' required, then the weaker coil may well be okay. It's only one step in wire gauge, so I doubt it's feasible to tell by eye.

If the other unit has the 940 coil and can deliver the ball up onto that raised playfield, then I think this one should be alright.

As a precaution, check the diode used to protect the drive transistor(s), too. If it isn't on the coil itself, I'd expect to find it near the TIP 36C on that 'PPB' board.

 

[Wintonmartin]

Replaced the transistor and worked a treat. Checked all the others inc resistors and diodes on the PPB for good measure.

Coil does seem a bit weak but only gave it a few tries to check it fired and the fuse didn't blow.

Shame about the time and the kids being in bed to give it a proper go.

Thanks for your help @Jay Walker @pinballmania