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Two dead coils at once! - advice?

PBrookfield

PBrookfield

Resident Uneconomical Repair Representative
Joined
Mar 23, 2017
Messages
1,338
Location
Wolverhampton, UK
Alias
Paul
Looking after this borrowed Black Rose. Has been fairly smooth sailing so far despite needing to resolder a coil wire or two, adjust a few dodgy switch wires, and lockpick the backbox lock because the key inside the machine was the wrong one (I have many random talents...)

But it's thrown me a curveball yesterday. Two coils pretty much stopped working at the same time, during a very decent game - the broadside VUK and the Pirate Cove lock kickback. They have no common fuses (all okay) no common wiring and no common driver. The VUK is a high-power coil with a TIP-36C and the lock kickback is a low power without one. On first blush I also can't see much common circuitry on the power driver board that would explain these two - and only these two coils - failing to operate.

Wires under playfield all OK and resoldered for good measure, correct voltage at both coils, connectors to backbox all good. Grounded out the TIP-102 transistors for both coils, and both coils fired happily, so I know the problems are not south of the backbox.

My questions are:
  1. My first response to this is going to be replacing the TIP-102s (and the TIP-36C for the VUK as it's a high-power coil) on the driver board, as these transistors are old and browned in either case - is this an appropriate first response to the above?
  2. I really do not like that both coils failed at exactly the same time. I'm going to start replacing diodes on the coils as a bare minimum, but does anyone have any ideas what I should be suspicious of that would cause this - or is it just unlikely bad luck that both coils had failures at the same time, presumably to either old age or bad diodes?
  3. Am I right to be looking just at the coil diodes and the power driver board for this or should I be really looking at the CPU board instead?
 
VUK is solenoid 1, Kicker is solenoid 9. So 9-1 = 8 which implies its a data problem. So reseat short grey ribbon cable and if that doesnt work, push the asic chip in all the way round. ( Power off to do all this )
 
pinballmania said:
VUK is solenoid 1, Kicker is solenoid 9. So 9-1 = 8 which implies its a data problem. So reseat short grey ribbon cable and if that doesnt work, push the asic chip in all the way round. ( Power off to do all this )
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That's a bloody good spot and call, didn't even think to work out if there was a common data line. Occam's razor would have it that you've nailed it - game was recently transported after all and I did find some distinctly un-snug connectors while piddling around. I'll check that out when I get home, thanks.
 
@pinballmania haha - well, I'm going to give you the points for diagnosis, because after reseating all of the ribbon cable connectors and giving the ASIC a few presses, turning the machine on gave me a bunch of coils latched on, a blown fuse and garbage on the DMD. As they say, feck, bugger, blast and bullocks. Old cables sustaining their connections through fairy dust and children's wishes, which I have destroyed by daring to touch them.

So that's a fuse needed now as well as some ribbons.

Gotta say I'm starting to prefer working on my System 11 though
 
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Ahh, if there's nothing good old IPA can't fix, it isn't worth fixing. Very healthy amount of good old black oxidation came off pins that had been mated presumably all their life prior.

All good now except for the single casualty on F115. Fuses, we love ya for sacrificing your life for us.
 
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Crazy how on the edge these pins can be. Do you use IPA on the board pins then? Is that good practice generally?
 
Durzel said:
Crazy how on the edge these pins can be. Do you use IPA on the board pins then? Is that good practice generally?
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Cotton buds (several as you will rapidly chew up the buds cleaning pins) soaked in IPA, giving the pins a good little scrub.

99.9% IPA (the stuff that is almost completely water-free and non-conductive) is absolutely fantastic for general cleaning of all electronics - post-soldering flux, corrosion, general dirt, the lot. Use it on your game console cartridges and the slot. Never have a load failure ever again, literally, and laugh mockingly at your younger self for foolishly blowing on carts.

I've got a 5L bottle of the stuff due to arrive after having used up a litre way faster than I thought I would when I first got it - it's just so good for general use it's crazy.
 
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Aye I've got a spray bottle of 99.9% in the cupboard. Good stuff.

Did you use the IPA on the connectors with the boards still installed?
 
Durzel said:
Aye I've got a spray bottle of 99.9% in the cupboard. Good stuff.

Did you use the IPA on the connectors with the boards still installed?
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Yep. No issues. For safety's sake let it evaporate before powering on - if you're not using WAY too much (e.g. you're spraying the board directly) this'll happen before you're done cleaning - but the 99.9% should be completely safe anyway.

The only thing IPA shouldn't go near when cleaning electronics, is any labels you really like, lol
 
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