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Sdtm drains from trapdoor in Theatre of Magic

Darthsinex

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Apr 22, 2014
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I have an annoying problem with my TOM where it consistently spits the balls straight out of the trapdoor and down the middle. There is a lot of play in the trapdoor cover itself and you can move it to a number of angles on the playfield just by touching it. Any thoughts on what to adjust?
 
I had the same issue on mine. Thought about slacking off the screws holding it to playfield underneath and giving it a little twist before tightening up (so angling from underneath rather than trapdoor cover) but never got round to it (now sold).
 
I spent weeks adjusting ours to be more consistent. It involved a new spring and coil sleeve which didn't change anything.

I had the whole mech apart multiple times, which is a pain. I tried changing the angle.

Eventually I put some rubbers on the plunger shaft so it had less umph!

The top of the trapdoor moving is normal, it's only loosely attached to the mechanism below which guides the ball. That part can wiggle however, as it rides up and down in a slot. Metal on metal over nearly 30 years does cause wear, often making the slot longer so the trap door goes higher when raised which can have an impact on the balls travel.

First I'd try a new sleeve but I'd say a newer one would make it more powerful and more likely to go sdtm if it's doing so now.

It's a really annoying mech to work with due to the way it works. You can't just stretch the spring out to give more tension like with a lot of VUKs as there's a spring on the top and bottom which act like a counter balance. If one is stronger or weaker the ball won't depress the switch.

It makes sense when you look at it 😄
 
The trap door bracket has a design fault. Its made of ferrous steel and the end stop for the brack (L Shaped metal at the end where the coil rests) often breaks or bends out of shape. I've restored 3 ToM's this year and all 3 needed to have the bracket replaced.

The replacement braket is made of stainless steel and as a result you'll need to change the coil to a higher strength to compensate for the sap in coil strength going from a ferrous based metal to a stainless steel metal.


This picture shows the original braket, notice how the end stop is bent, this what I'm referring to.

PXL_20230806_182454152.jpg

New coil is FL-11753/50V

PXL_20230806_185121974.jpg

Bracket can be purchased from:


or


The usual coil sleeve, spring advice holds true, replace them as advised.

Cheers,

Scott
 
Anyone after a Theatre of Magic trap door weldment then I have one for sale. Bought one too many when I was doing my refurb.
If interested then ping me a PM.
D.
 
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