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Sys11 Coil locked on, lots of coils not working

David_Vi

David_Vi

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Having a great day 🙄

Bk2k arrived today, due to Diner (also having a big issue) we didn't try bk till now.

Played well for five minutes then I noticed the outhole coil wasn't working.
So took a look then tried another game.
Smelt burning and noticed the left drop target reset coil was stuck on and smoking.

Desoldered the wires to it and did a bit of investigating, a few coils won't work at all now.

How do I diagnose this? Board stuff like this is above my level. I only just learned how to use the sys11 service menu🤦‍♂️🤣

Cheers
 
Tried a coil test.
These are the ones that aren't working incase it gives any hints.

outhole
Ball serve
Right eject

When I test the voltage of the non firing coils it's erratic. Working ones seem to stick around 7v so hopefully that's an indicator too
 
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if you desoldered wires to one coil - have you by mistake now disconnected the power to those other coils? (i.e the power could be daisy chained from one coil to another so by disordering you may have broken the chain?
 
Coil stuck on and not blowing a fuse - I would check that it isn't overfused (common issue).

I assume you've found the manual - it's on the IPDB page: https://www.ipdb.org/files/311/Williams_1989_Black_Knight_2000_Operations_Manual.pdf

Sys11 have this thing where the coils are duplexed via some relays, so each mosfet actually controls 2 coils/flashlamps. In the case of the left 3-bank it's Q32 which also "Bolt Circle Center Flasher" - does that lamp work at all?

Remember that the coils always have their VDC at one end, and the mosfet completes the circuit by closing the GND side. Is it possible that that coil's ground wire (Vio-Orn) is accidentally shorted to some ground connection?
 
AlanJ said:
if you desoldered wires to one coil - have you by mistake now disconnected the power to those other coils? (i.e the power could be daisy chained from one coil to another so by disordering you may have broken the chain?
Click to expand...

It only had two wires, could that still be the case?

20220316_224707.jpg

Fubar said:
Coil stuck on and not blowing a fuse - I would check that it isn't overfused (common issue).

I assume you've found the manual - it's on the IPDB page: https://www.ipdb.org/files/311/Williams_1989_Black_Knight_2000_Operations_Manual.pdf

Sys11 have this thing where the coils are duplexed via some relays, so each mosfet actually controls 2 coils/flashlamps. In the case of the left 3-bank it's Q32 which also "Bolt Circle Center Flasher" - does that lamp work at all?

Remember that the coils always have their VDC at one end, and the mosfet completes the circuit by closing the GND side. Is it possible that that coil's ground wire (Vio-Orn) is accidentally shorted to some ground connection?
Click to expand...

I am learning all of this now, and still struggling to understand it.

In trying to see if bolt circle flasher works I have noticed every flasher in the test sets off the same flashers and not the ones they're supposed to.

See here
https://photos.app.goo.gl/CmuwhwkRyukg27Ku5

That's weird 😔

My first sys11s and both are screwed. Never had these issues before!
 
The bolt circle flasher is the one that goes off on every flasher test, rather than the correct flashers, I was too tired and defeated last night to make this connection.

What would that mean? Does it narrow it down?
If that goes on every time the relay kicks it to the C Power using my novice brain I assume what powers that and the drop target reset solenoid are stuck on? (Kinda knew this) but why would none of the other flashers work (except one other 'ramp flasher' ,see video above)

Logic Probe arriving tomorrow, a bunch of transistors (just incase) hopefully by Monday.
 
David check the simple stuff first. Presumably you had to reconnect the idc connectors back on the interface board when you reassembled the machine. Maybe the connectors are on wrong . The relay sounds like it is working in the video and at least some of the coils are firing so there seems no simple reason at the board why the corresponding flashers shouldn't also work.
 
Asiapinball said:
David check the simple stuff first. Presumably you had to reconnect the idc connectors back on the interface board when you reassembled the machine. Maybe the connectors are on wrong . The relay sounds like it is working in the video and at least some of the coils are firing so there seems no simple reason at the board why the corresponding flashers shouldn't also work.
Click to expand...

100 % Agree. Take a breath and start from the beginning. More often than not these issues aren’t are as horrific as they first appear.
Check the simple stuff one thing at a time … before you go balls deep with logic probe , desoldering stuff , swapping components and get yrself in a world of confusion. 😁
 
Asiapinball said:
David check the simple stuff first. Presumably you had to reconnect the idc connectors back on the interface board when you reassembled the machine. Maybe the connectors are on wrong . The relay sounds like it is working in the video and at least some of the coils are firing so there seems no simple reason at the board why the corresponding flashers shouldn't also work.
Click to expand...

It came all assembled, I didn't need to attach any connectors and the game appeared to perform fine for two or three games.
Maybe that reset coil was locked on that entire time, but I think it would have melted more or blown a fuse by then. So feel it was a later failure.
 
And did you see it working prior to buying it. I have had machines arrive non working because previous owner tried random stuff to fix it. You need to be methodical and work through everything and I would start with all the wiring rather than the board as your video shows you have some action at the board.
 
Plus if it is an issue at the board it may well have been caused by shorts on playfield and wiring and you don't want to get a repaired board back into a machine only to find that it blows again due to problem elsewhere
 
Why has no-one suggested that the fuse might have blown when the coil smoked. That will stop other coils working. Check the simple stuff first.
The smoked coil will need replacing, and the driving transistor at least will also need to be replaced at the same time.
 
Nothing looks untoward, seller is a respected member of the UK community and for a sys11 that hasn't had a total restore it appears to be in really good condition. So I'm sure it's an issue that's happened since getting here if not in transit.
It seems unlucky that a transistor or other components could fail as soon as it gets here but I'm sure there's a fine chance

Asiapinball said:
Plus if it is an issue at the board it may well have been caused by shorts on playfield and wiring and you don't want to get a repaired board back into a machine only to find that it blows again due to problem elsewhere
Click to expand...
Yes same thing with Diner, I need to find the potential short before repairing it 😳
 
pinballmania said:
Why has no-one suggested that the fuse might have blown when the coil smoked. That will stop other coils working. Check the simple stuff first.
The smoked coil will need replacing, and the driving transistor at least will also need to be replaced at the same time.
Click to expand...

I tested fuses but didn't pull them so that is on my list.
I don't understand if that would cause the strange behaviour here though.
https://photos.app.goo.gl/sCzpL3YyvvG7ACx48

You folks are the seasoned experts though so I am trying to learn 😳😁
 
run the solenoid test and ascertain exactly which coils work, and which ones don't. The ones that dont work will have a commonality which will point you at the problem. Coils should have 50-70V at them when operated, but you'll have problems measuring this, because you need the AC select relay to be working otherwise power is routed to the C-side ( flashers etc ) rather than the A-side (coils ). USe solenoid test to check that AC select relay is working. Refer to page 29 of manual for solenoid listing.
 
the centre circle flashers, and the two in the backbox are locked on. They share the same drive as the melted coil. That transistor needs to be removed and replaced.
It looks like the AC select relay is working ok, so you probably have a blown fuse. You cannot test fuses whilst installed, you'll get false readings.
 
pinballmania said:
run the solenoid test and ascertain exactly which coils work, and which ones don't. The ones that dont work will have a commonality which will point you at the problem. Coils should have 50-70V at them when operated, but you'll have problems measuring this, because you need the AC select relay to be working otherwise power is routed to the C-side ( flashers etc ) rather than the A-side (coils ). USe solenoid test to check that AC select relay is working. Refer to page 29 of manual for solenoid listing.
Click to expand...

Does the video I posted above show the relay is working?

Screenshot_20220317-012602_Drive.jpg
Screenshot_20220317-063520_OneDrive.jpg
Coils that don't work:
Outhole kicker
Ball serve
Right eject hole

Left 3 bank drop target reset is the locked on one and in coil/flasher test it's flasher on C is the one that lights up on every flash test. (Maybe it's supposed to but the other flashers don't work and if they do they're dim.

Edit: see you've since replied and noticed that locked on flasher. Got some transistors coming next few days . Hopefully that's the solution?


I haven't got down to the pin today to try any suggestions but will try before the days get busy!
 
Ruaraidh said:
You should be able to hear the A/C relay clicking as part of the coil test.
Click to expand...
Yup it does!

I just want to confirm the transistor is dead, but when I test with a multimeter I don't see any difference to the others.
 
David_Vi said:
I just want to confirm the transistor is dead, but when I test with a multimeter I don't see any difference to the others.
Click to expand...
How are you testing it? With the board unplugged, meter in ohms mode, any pair of the fet's legs read zero?
 
David_Vi said:
Yup it does!

I just want to confirm the transistor is dead, but when I test with a multimeter I don't see any difference to the others.
Click to expand...
It might be the drive transistor, but equally it might be the pre-drive transistor, it might be the 7408 IC U19 that drives the pre-drive transistor, it might be even further back to the LS374 IC U28 that drives the 7408 (i doubt it - but its possible).

Again your logic probe, when it arrives will help a lot
 
Just need to perform a diode test between base emitter and base collector to make sure that you don't have a short. Diode mode on your Multimeter. Check each pair in both directions to make sure that you get a voltage drop one way and nothing the other.
 
Tested all fuses out of holders and good.

Diode test on Q32
Right leg to centre 0.144
Left leg to centre 0.600 - 0.700 (can someone clear up which probe I should be using because it varies if I switch between input and com but the right leg doesn't change at all.

So was Q32 killed by the locked on coil?
Would it also explain the others not working even though they're on different transistors?
 
The voltage on working coils sits around 73v on both lugs.

The ones not working show an erratic always moving voltage.
However one lug of the wire feeding the locked on coil shows 73 while the other is erratic.

If someone can explain why, that would be appreciated
 
As with the Diner, would it be better to send away the circuit board for repair, and check through the solenoid and flashbulb wiring while waiting? The solenoids are fused in groups, but some of those you have not working (outhole, ball feeder and eject, No's 1,2 and 8, use 25v, while the target reset, No.3, uses 50v. As you realise, the first eight solenoid drives are subject to a 'solenoid extender', which Williams refer to as the A/C relay. A for relay Off, C for relay On. The A side is usually for solenoids, and the C side for flashbulbs, though there are strange usages with the reverse, e.g. Road Kings. The later System 11 games like this are a bit tidier with regard to the A/C set-up, the relay and the network of heavy diodes are all on the 'Aux Power' circuit board, along with eight additional coil drive transistors for the heaviest loads, requiring a 3rd driver stage (TIP 36C transistors). The target reset seems to be one of these, according to the schematics it's Q1. With the heavy diodes being D33 and 34.

There shouldn't be ripple like that on the displays, either. Maybe one of the power rails for them is failing.
 
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Jay Walker said:
As with the Diner, would it be better to send away the circuit board for repair, and check through the solenoid and flashbulb wiring while waiting? The solenoids are fused in groups, but some of those you have not working (outhole, ball feeder and eject, No's 1,2 and 8, use 25v, while the target reset, No.3, uses 50v. As you realise, the first eight solenoid drives are subject to a 'solenoid extender', which Williams refer to as the A/C relay. A for relay off, C for relay On. The A side is usually for solenoids, and the C side for flashbulbs, though there are strange usages with the reverse, e.g Road Kings. The later System 11 games like this are a bit tidier with regard to the A/C set-up, the relay and the network of heavy diodes are all on the 'Aux Power' circuit board, along with some additional coil drive transistors for the heaviest loads, requiring a 3rd driver stage (TIP 36C transistors). The target reset seems to be one of these, according to the schematics it's Q1.

There shouldn't be ripple like that on the displays, either. Maybe one of the power rails for them is failing.
Click to expand...

Jim said he'll take the board back if it's just one thing. I'd like to find out what's dead first if I can!


Ripple? I think that's just the video
 
Something to check for Solenoid 3 is transistor Q1 on the Aux Power board. When there are three driver stages, the progression is logic gate output > pre-driver transistor > Darlington pair transistor (all these on Cpu/driver board) > TIP 36C transistor on Aux Power board.

Speaking of gate outputs, the outhole, feeder and l/h target reset (No's 1, 2 & 3) are all switched from the same gate chip, Cpu U20, but the other non-working solenoid, r/side eject, is No.8 and switched from U19. I'd wondered if the four affected circuits were all using the same chip, which might have been damaged by the coil failure. It's still possible that is has, but Solenoid 4 (the other drop target reset) is the other drive from U20,

If the apparent display ripple is down to video frequency, that's a relief.
 
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