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Twilight Zone lock release not releasing


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Question

It just decided not to release the ball. Fuse is fine, switch is fine (it makes the sound effect to release it) and I can manually fire it by earthing the pin at the driver board. Any ideas?
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Ahhh the dammned TZ. Without looking at the drawings if it's a release solenoid and if your activating it by grounding it it may be the driver transistor and or predriver on the driver board. Does it work in the solenoid test as that will tell you if its switching on the transistor, if it does then the transistor is ok. On the opto board I think they have 3 X LM339's IC's ( guessing I could be wrong here) they switch when the opto's are interrupted. Find whcih one controls the affected area and change it. Socket it if it already isnt but this is a fault repair once all others are exhausted.

 

- - - Updated - - -

 

Hmm, I have had a problem with the trough Proximity Sensor for a while but that shouldn't effect the lock release should it?

 

Thats often a flakey eddy sensor connector which can be fixed by directly soldering the wires to the PCB and re flowing the solder pads

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I was hoping that it wasn't one of the transistors. No it doesn't work in the solenoid test. I also have soldered the eddy board (which fixed it for a while) then replaced the small coil the second time and it has just recently failed again
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Do you have a multimeter to check the transistors and a soldering iron to change if faulty?

 

I do have both but don't have the transistors on hand unfortunately. Do the transistors blow for no reason or does something cause them to go?

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Yeah, sometimes these things happen. Being a Darlington transistor, they are designed to handle a fair bit of current (8 Amps), so even if it was drawing to much current because your coil was no good, you probably would have blown a fuse first I would say.

 

Test them and change out if faulty and you should be right to go.

 

This is how that part of the circuit works if you would like to know.

859373571_PowerDriver.thumb.png.c35710c2d3d72b274df4ba571ed05b11.png

Edited by Mosfet
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If you find the problem to be the opto board, don't go changing IC's just yet.

Remove capacitor C1 & check for corroded tracks underneath it.

The 12v buss from this cap splits off into two different directions & usually only one spur is affected, knocking out one side of the opto board.

This can fool people into thinking that the board is still functional, as the power LED & other optos still work.

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Still not sure what it is as the transistors seem ok by the meter. Wouldn't think it's the opto board cause the first lock is a micro switch which reads fine and the sound effect to eject it keeps repeating when the ball is in there. Just had the boards overhauled with all caps and BR's replaced so it shouldn't be that either. Got me stumped atm. The coil looks perfect and operates ok manually as well. Just wondering if a ribbon cable or something silly is going on. Also double checked the 3 amp slo-blo is fine too.
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As mentioned use the internal test feature. In switch test are your opto's working? Check your switches first if they are OK and the 12v for opto's, then go into switch edge test and check them individually with the ball. If this doesn't pass then it maybe a few things the 12v missing or it's the opto board or maybe a broken connection/wire. If it passes then again go into solenoid test. If the solenoid in question doesn't fire and you've done the usual ground tests to activate it, it's most likely the transistor. Coils can look perfect but you must test them for continuity looking at it won't show a broken wire. Cheap to replace.
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Still not sure what it is as the transistors seem ok by the meter. Wouldn't think it's the opto board cause the first lock is a micro switch which reads fine and the sound effect to eject it keeps repeating when the ball is in there. Just had the boards overhauled with all caps and BR's replaced so it shouldn't be that either. Got me stumped atm. The coil looks perfect and operates ok manually as well. Just wondering if a ribbon cable or something silly is going on. Also double checked the 3 amp slo-blo is fine too.

 

1. Does the coil fire if you ground the tab of Q46?

2. If not, then do you have +50v between both tabs of the coil & the ground braid in the cabinet?

If there's 50v present on only the tab that connects to the violet/orange wire, you have an open circuit coil.

If there's no 50v on either tab & other coils on that line work, you have a break in the line somewhere, most likely on another coil.

3. If you have 50v present on both tabs & the transistors are fine as you say, you'll be missing the logic signal to fire the transistors.

This will be either because you have a faulty CPU-Driver ribbon cable or a bad contact on the ASIC.

Usually, just cleaning the pins on & reseating the ASIC chip cures this issue.

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1. Does the coil fire if you ground the tab of Q46?

2. If not, then do you have +50v between both tabs of the coil & the ground braid in the cabinet?

If there's 50v present on only the tab that connects to the violet/orange wire, you have an open circuit coil.

If there's no 50v on either tab & other coils on that line work, you have a break in the line somewhere, most likely on another coil.

3. If you have 50v present on both tabs & the transistors are fine as you say, you'll be missing the logic signal to fire the transistors.

This will be either because you have a faulty CPU-Driver ribbon cable or a bad contact on the ASIC.

Usually, just cleaning the pins on & reseating the ASIC chip cures this issue.

 

Well I'll be BUGGERED!!!

I reseated the ASIC chip and BINGO!

Something as simple as that. I would never have thought it would have been that.

Sparky you know your stuff and you are a legend.

THANK YOU mate

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