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Weak Flippers - what else can I check?
- Thread starter MarkS
- Start date
mplayfield
Site Supporter
I have diodes I can take one with me to Johns if yo want. What number is on it
You should have diode test function on your multimeter BUT you have to cut off one leg to test it, so it’s easier to just replace with a new diode. Test the old one. If it’s faulty ie conducts in reverse direction then that’s your problem, if not, you still have a problem elsewhere.
mplayfield
Site Supporter
Thanks , I have those so will bring with me tomorrow @MarkS
I can only read the last 3 digits which are 007 - thanks @mplayfield
I don't have a multimeter, guess I will be back on YouTube to learn how to use one
Any recommendations?
I don't have a multimeter, guess I will be back on YouTube to learn how to use one
Any recommendations?
mplayfield
Site Supporter
Just change it easiest wayI can only read the last 3 digits which are 007 - thanks @mplayfield
I don't have a multimeter, guess I will be back on YouTube to learn how to use one
Yes I will change it, I just figured it was worth doing the check mentioned above to prove that's the issue before I turn it back on and blow another fuse? (Bound to need one later for something else too)
Also, I'm confused re the whole diode thing now - I thought a diode only allowed current to pass in one direction, so if it's in back-to-front why doesn't it just "not work"? If it's back-to-front, and then broken, how does this blow the fuse?
Don’t feel stupid, we have all done it. Repeatedly.
Last time I replaced a flipper mech with new plunger and sleeve etc, I put the coil on back to front *even though* I had taken pictures to prevent exactly that. I forgot to account for the fact the coil was incorrectly aligned before I started work (the lugs end of the coil should ideally be away from the end stop where the max vibration happens) so when I put it back together correctly, my photo became inverted.
Anyway within milliseconds the 70V blew 2 transistors on the board. I can’t remember if I also blew the coil diode or not, but probably. Then I also gave myself an electric shock off the board, prodding with my finger to see if a connector was loose.
Flipper coils have three lugs, two windings - one for the flip and another for the ‘hold’. I had fried the ‘hold’ transistors so my flipper would now flip but instantly drop back.
Fuc_king pinball. We should collect stamps or something instead.
Last time I replaced a flipper mech with new plunger and sleeve etc, I put the coil on back to front *even though* I had taken pictures to prevent exactly that. I forgot to account for the fact the coil was incorrectly aligned before I started work (the lugs end of the coil should ideally be away from the end stop where the max vibration happens) so when I put it back together correctly, my photo became inverted.
Anyway within milliseconds the 70V blew 2 transistors on the board. I can’t remember if I also blew the coil diode or not, but probably. Then I also gave myself an electric shock off the board, prodding with my finger to see if a connector was loose.
Flipper coils have three lugs, two windings - one for the flip and another for the ‘hold’. I had fried the ‘hold’ transistors so my flipper would now flip but instantly drop back.
Fuc_king pinball. We should collect stamps or something instead.
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Indeed.
My other favourite cock up is removing the component from a board , do a lovely clean job of it , then realising it was the one beside it you should have done and you only have one spare to hand ….. asaaagh
I now triple check and mark the component / board with a sharpie to guard against distraction and general f***wittery
mplayfield
Site Supporter
If the diode is in the wrong way round it will short out your flipper voltage to ground. The diode is there to deal with a phenomenon called “back emf” - when you flip a flipper the electricity produces magnetism that moves the plunger. When the electricity is cut to the coil the magnetic field collapses and this produces electricity in the opposite direction of the direction to its original electricity supply. That spike of energy can destroy your electronic circuitry, so the diode is there to conduct it away by effectively shorting out the reverse circuit.Yes I will change it, I just figured it was worth doing the check mentioned above to prove that's the issue before I turn it back on and blow another fuse? (Bound to need one later for something else too)
Also, I'm confused re the whole diode thing now - I thought a diode only allowed current to pass in one direction, so if it's in back-to-front why doesn't it just "not work"? If it's back-to-front, and then broken, how does this blow the fuse?
So in normal flipper operation when power is applied, the diode does nothing because it can only conduct one way. Once the power is switched off, it conducts the back emf voltage away.
If you connected it up the wrong way round it will have conducted a relatively high voltage and high current when you pressed the flipper button. and may now be damaged such that it conducts in both directions.
Hope this makes sense.
Thanks so much for the explanation AlanJ, I think it makes sense... hadn't thought about what happened when the magnetic field collapses 
Thank goodness you aren't a surgeon then
My other favourite cock up is removing the component from a board , do a lovely clean job of it , then realising it was the one beside it you should have done and you only have one spare to hand ….. asaaagh
I now triple check and mark the component / board with a sharpie to guard against distraction and general f***wittery
Thank goodness you aren't a surgeon then
The effects can be unpredictable; a High Speed that I played as a punter partly crashed on making the ramp shot with the upper flipper. The displays and feature lamps blanked out, the switch matrix stopped responding, but the flippers themselves, the bumpers and slingshots still worked, along with the background music. Turning it off and re-booting it had it apparently okay again. That very machine was in disgrace at the workshop when I applied for work - a later repeat had seen a few coils lock on and burn out. The primary culprit was the broken open-circuit diode on that upper flipper. It wasn't a first-tier machine any more in 1989, but it served for a bit longer after being rehabilitated.
The marking on the diode on coils was an indication of which was the live terminal, if I was intending to check a solenoid by jumpering it to ground. The later system 11 games no longer had diodes on all the coils; they were still used, but some were on the new-fangled 'Aux Power' board instead.
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Sooo... I replaced the diode (thanks @mplayfield) and now the flipper is flipping but with another problem - with a single soft, quick press of the flipper button it seems to flip OK. But if I hold the flipper for any length of time it flips repeatedly very quickly and the flipper mechanism sparks repeatedly too. I have checked the EOS switch which looks fine, what exactly would cause this behaviour? I thought the EOS switch activated a lower current (?) to hold the flipper in place, so does this mean that isn't working and the coil is firing repeatedly/rapdily?
Hold coil broken maybe? EOS switch should be normally closed on your setup, this will allow power to flow from the always on cable via the green white cable to the EOS and back again to the middle lug of the coil. Middle lug should have the thick cable going into the coil. Once the EOS opens, the middle lug is disconnected from power, but the thin cable going to the outer lugs still has power. That is the hold coil. Now check if the EOS is opened correctly. lift the flipper to the end of its stroke manually and press the flipper button. It should stay up. If it isn't, your hold coil is broken. Is the thin cable securely soldered on both outer lugs? With pin off, what is the resistance between the outer lugs (Don't measure the diode!)?
As the good doctor says above ….. if that thin hold wire is broken that will cause machine gunning of the flipper.
It’s very thin and easy to break or desolder if you are working on those lugs.
It’s very thin and easy to break or desolder if you are working on those lugs.
Thanks for the explanation! I think that makes sense... so it all looked OK at first inspection, but I gently tried moving the thin wires and lo and behold one of them isn't connected. The problem is that it's too short and doesn't really reach the lug, how can I fix that? It reaches the end of the diode leg, can I solder it onto there presumably?
Yes, you can. It is very likely to fail again though as there is a lot of vibration there. Depending which end it is you may be able to unspool one winding clean off the laquer, wrap it round the lug a few times and resolder. Will be another coil in due course otherwise.
Thanks... understood re longevity of it all, but it's all been a good learning experience (and what I'd hoped to get when I bought this!). I managed to pull the thin wire down another 5mm through the coil paper which was enough to get a loop around the diode wire... soldering is not very neat but it's connected and now working!
Thanks to everyone for their help, hopefully others might stumble across this thread in future and find something that helps them
Some more de**il, if it'll help;
With a 'serial-wound' coil like that, where the two windings meet at the centre terminal, the EoS switch shorts out the secondary hold winding until it opens, at which point the circuit becomes a series connection through both windings, cutting the current flowing. If the hold winding's broken, there's an open circuit when the switch opens, so the flipper falls back, closing the switch again and re-energising the coil. Apart from the nuisance, the coil will then overheat quite quickly.
The more modern parallel-wound coils have both winding begin at the live terminal, with the power winding appearing at the centre, and the hold at the tail. The coil is basically two parallel circuits; the power winding and EoS switch, in parallel with the hold winding. The switch opening cuts off the power winding altogether, leaving the hold winding on its own. Again a failed hold winding sees the flipper 'chatter' repeatedly, and overheat if it's held long enough.
The Williams Fliptronic systems (and, apparently, CGC remakes) have a protective measure for a failed hold winding; the flipper board will only pulse the power winding twice before switching off.
With a 'serial-wound' coil like that, where the two windings meet at the centre terminal, the EoS switch shorts out the secondary hold winding until it opens, at which point the circuit becomes a series connection through both windings, cutting the current flowing. If the hold winding's broken, there's an open circuit when the switch opens, so the flipper falls back, closing the switch again and re-energising the coil. Apart from the nuisance, the coil will then overheat quite quickly.
The more modern parallel-wound coils have both winding begin at the live terminal, with the power winding appearing at the centre, and the hold at the tail. The coil is basically two parallel circuits; the power winding and EoS switch, in parallel with the hold winding. The switch opening cuts off the power winding altogether, leaving the hold winding on its own. Again a failed hold winding sees the flipper 'chatter' repeatedly, and overheat if it's held long enough.
The Williams Fliptronic systems (and, apparently, CGC remakes) have a protective measure for a failed hold winding; the flipper board will only pulse the power winding twice before switching off.