Hi all, could do with some help on a Doozie I thought I'd finished repairing

Doozie has a Trip coil that opens the zipper flippers. I replaced the burnt one as part of my repairs - figured whatever caused that I would have fixed by generally cleaning and checking every switch, etc.

So, played machine several times, all good. Switched off at the extension lead I use for a couple of machines (that do not have on/off switches). Switched extension lead back on to play another machine. Doozie actually has power but not lit up as have not pressed left flipper.

Week or so later I go to play Doozie. Nothing. 15a fuse blown. Replace and blows. Put in my circuit breaker, reset the large relay bank (includes start relay), power on, good, put in new 15a fuse, all good.

Notice zipper flippers close but do not re-open. Notice trip relay is toast. Power off, tools out, remove coil.IMG_4670 (resized).JPG

here's the part of the schematic I focused on showing this Trip relay
Capture (resized).JPG
Put volt meter across the two feeding trip coil.

Readings starting from complete power off:

1. On/off Toggle switch ON (Start Relay energizes) = 22.8V
2. Press Left Flipper (Lock relay on, GI on) = 21.5V
3. Press Credit button (machine resets correctly) = 10.9V (so zipper flippers seemed ok as this was not enough volts to pull in)
4. Press Open Target (would energize trip) = 27V

So, 4 is correct, but obviously the others are not. Coil would have been getting 22.8V for a week while machine was switched on (even though no lights as had not pressed left flipper)

So, going back to schematic, I checked with DMM set to Continuity between the Blue/BR wire at coil ("x") and the other side of all the switches that I marked with red lines. Found the EOS switch (in yellow) was closed at rest. Set gap, thought that was it. No, no change (which makes sense as at step 1 above, Game Over switch would be open anyway).

So, there is no continuity between the Coil Blue/BR and the other side of the 6 switches, but its getting "some" voltage somehow??

One other thing. I checked resistance between the same ("X" and red lines) and there's a reading of around 30M ohms? That more than just holding the DMM leads in my hands but is it enough to let that voltage flow, and therefore there's some "leakage" somwhere.

As you can all see, I'm now way out of my depth with the whole electronics bit - would love some ideas / advice!

Hi Rolf! Glad you are here.

I double checked the Trough relay it is open. I checked continuity from X wire on my picture above to Red/Blackand the switch is definitely open. Here the photo as well. Middle switch at rear.
IMG_4673 (resized).JPG

There must be a "short" somewhere but I cannot see it! (The machine has a toggle switch then left flipper turns on GI / Lock relay) but I'm getting 22.8 V just on Toggle On before Left Flipper / Lock relay.

Any other thoughts Rolf or others?

first, thanks for the replies.

EM-PINMAN I believe thats just camera angle, all the switches test ok with a meter.

rolf_martin_062

1. Have not replaced coil yet, awaiting delivery. But I suspect yes, I will be able to play because I could before it burnt out. I think that is becuase once the game resets and you are playing the coil "only" gets 10.9V (see my first post) which is probably not enough to pull it in. And when the Open target gets hit, it gets the correct 27V (see 1st post again).

2. Yes, there is a fault because the coil is getting 22.8V all the time when the machine is on (toggle switch on) but no lights (have not pressed left flipper) - after an extended time the coil fries.

OK, game over relay:

It is just one relay (part of a long bank of relays).

Here's the sequence from complete power off:

1. No voltage at coil (obviously) and game over relay is not pulled in
2. On/off toggle switch ON = Game Over Relay pulls in and stays pulled in. Voltage at coil: 22.4 (AC) !!
3. Press Left Flipper = Lock relay pulls in, lights com on, Voltage at Coil: 21V !!
4. Press Credit Button = Game resets correctly, including resets bank including Start Relay. Voltage at Coil: 10V !!

(!! = I'm sure all the above the voltage should be 0)

Hit the "Open" target, Voltage at coil = 27V. This is the only correct reading (as this is when indeed the coil should get voltage).

As I said in post 1, I find it weird that if I measure resistance between Blue/Brown "X" connection on the coil, to the other side of any of the switches (yellow) involved I get 30M ohms (Surely it should be 0)- and that 30M does indeed drop to 0 if I press either the left open target switch, right open target switch of the Flipper EOS switch??? I maybe chasing shadows with this resistance stuff??

rolf_martin_062 you are my saviour once again! Your mobile phone story made me think that I was wasting my time with the volt meter. Then you reminded me of the closed EOS switch. Then....the penny finally dropped (=I realized the problem):

When the game was sitting with power on and game over relay switch closed, the closed EOS switch was causing the coil to be permanently on. Doh!!!

The voltage reading was indeed completely misleading.

And to prove it, I took your advice and made SteveFury 's tester (Thanks, Steve):
IMG_4681 (resized).JPG
And sure enough it proved everything now working correctly.

Thanks Rolf!!