Help Needed: Williams Comet Solenoids not working

Hi,

I need some ideas on how to troubleshoot a Comet machine whose solenoids do not work.

Background: This machine only starts in Accounting Mode. When it was playable, we had to deal with the fact it only started in "04" mode. It was still this way when we started having problems. Recently, as we were playing the machine one of the Bumpers Solenoids actually started smoking and turned black. We replaced the solenoid with a new one but none of the solenoids work now. I have a multimeter and was able to check the pins on the Power Supply board and they all reported about 5V. We've also changed out all of the fuses, looked for any obvious loose wires, checked wire connectors, etc. We also looked for any voltage readings on many of the solenoids and the readings are 0.

We've gone through the diagnostics (CPU board says it's fine) and everything seems fine except the Solenoids.

When we start the machine, we can add credits, but the ball kicker does not kick the ball out. The flippers work randomly, but most of the time they do not.

I'm searching for ideas on how to troubleshoot this logically, correctly, etc. Any help is appreciated.

#2 6 years ago

DAV

wayout440

Pinside member

OP
Quoted from Steve_PBH:
pins on the Power Supply board and they all reported about 5V.... We also looked for any voltage readings on many of the solenoids and the readings are 0.

OK, this is where I would start. Check this connector. Your solenoids are not going to work on 5VDC, much less 0. Should be around 23 to 33 VDC from 3J3-3 to 3J3-6,7, and 8

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#3 6 years ago

???

pindel

Pinside member

12y 53,300 718 1

If coils did burn i'm assuming it was from a bad transistor. New coils will just fry again. Look at manual for location of transistor for burnt coil. Check it and it is likely shorted. Replace bad transistors.
Once transistors are replaced, I would power game with playfield harness unplugged. Plug harness quickly with game on to see if any coils fire. You can see if any coils fire and unplug quickly before you blow the transistors again. I learned this the hard way. I hope this makes sense. Transistors are easy to replace on board.

#4 6 years ago

DAV

wayout440

Pinside member

Quoted from pindel:
If coils did burn i'm assuming it was from a bad transistor. New coils will just fry again. Look at manual for location of transistor for burnt coil. Check it and it is likely shorted. Replace bad transistors.
Once transistors are replaced, I would power game with playfield harness unplugged. Plug harness quickly with game on to see if any coils fire. You can see if any coils fire and unplug quickly before you blow the transistors again. I learned this the hard way. I hope this makes sense. Transistors are easy to replace on board.

Eh, I'm trying to slow this down a bit. I thought that as well. Good to at least disconnect a wire off the coil that was replaced, because chances are that once solenoid power is restored that coil is going to lock on because the transistor is already damaged. It seems solenoid power is completely lost from the opening post.

#5 6 years ago

DAD

Steve_PBH

Pinside member

Thanks for taking an interest in the problems I'm having with Comet. I'd be lost without help.

I tested the connector as suggested. The readings were really low, or almost nothing. (.18-.2ish) on 6,7,8 to 3.

Even though I read the transistor part of the discussion, I have not done anything else. I thought I better wait for the next instructions first,

I really appreciate the help. Thanks, again.

#6 6 years ago

DAV

wayout440

Pinside member

No problem. With your meter set to DC volts, put the black (ground) probe on the ground pin and touch the red (positive) probe to each side of the fuse clips on F2 solenoid fuse... You should have voltage on each side. If you have it only on one side, the fuse is blown. If you have voltage on both sides, problem is between fuse and 3J3. If you have nothing on either side, problem is upstream from the fuse.

#7 6 years ago

DAD

Steve_PBH

Pinside member

Today's Update:

I tested both sides of the F2 fuse and the Ground on 3J3. The left side gave me no readings, and the right test showed voltage. I then pulled the F2 fuse and did a quick continuity test on it, and the fuse was bad. I placed a new 2.5A S.B. (I tested it first, and it was good) in the fuse clips and fired up the machine. The solenoids did not work. So I tested the F2 Fuse Clips again with 3J3 and only the right side had power. I pulled the fuse and it tested bad.

So in short, the fuse did not last 10 seconds when put into the machine.

What should I do for a next step.

Thanks again, for your help.

#8 6 years ago

DAV

wayout440

Pinside member

https://pinside.com/pinball/forum/topic/making-and-using-a-fuse-breaker

OP
Quoted from Steve_PBH:
Today's Update:
I tested both sides of the F2 fuse and the Ground on 3J3. The left side gave me no readings, and the right test showed voltage. I then pulled the F2 fuse and did a quick continuity test on it, and the fuse was bad. I placed a new 2.5A S.B. (I tested it first, and it was good) in the fuse clips and fired up the machine. The solenoids did not work. So I tested the F2 Fuse Clips again with 3J3 and only the right side had power. I pulled the fuse and it tested bad.
So in short, the fuse did not last 10 seconds when put into the machine.
What should I do for a next step.
Thanks again, for your help.

Buy more fuses ...only half kidding. As a side note, if you really wanted to save fuses, there's a link below how to substitute a resettable breaker for tough cases. I've never needed one, usually I can get by blowing a few fuses.

Anyway, usually what happens on these "power on - blows the solenoid fuse right away" cases is a solenoid is locking on. So the typical troubleshooting is to install a fresh fuse, turn on the power, and look for a solenoid activating. You already know the pop burned out, so it is likely that you have a driver transistor for that pop shorted. Identify which pop you replaced the coil on, and compare that to the solenoid chart and replace the driver transistor. Then power up the game without the solenoid driver output connected (or, disconnect the power wire from the pops coil) then power up and make sure the solenoid power works/ look for any other problems.

#9 6 years ago

DAD

Steve_PBH

Pinside member

Well, I have 3 2.5A SB fuses left to burn out before I have to get more.

The Pop that burned out was the Upper Jet-Bumper. In the manual, that is #19. They System-9 Solenoid Table shows the Drive Trans as Q79 (a TIP122 which looks like it is in the right upper corner of the CPU board).

Does this seem correct?

#10 6 years ago

DAV

wayout440

Pinside member

OP
Quoted from Steve_PBH:
Well, I have 3 2.5A SB fuses left to burn out before I have to get more.
The Pop that burned out was the Upper Jet-Bumper. In the manual, that is #19. They System-9 Solenoid Table shows the Drive Trans as Q79 (a TIP122 which looks like it is in the right upper corner of the CPU board).
Does this seem correct?

Yes Q79. Please accept my apologies. I was also helping someone with a Stellar Wars and quoted the wrong transistors in my earlier post. Q79 is probably shorted and needs replaced.

2 weeks later

#11 6 years ago

USA

SilverballSleuth

Inactive member

6y 58,800 1,205

Steve_PBH - have you come to a solution? I brought home a Comet today and all coils will not fire, except for flippers. I'm also stuck in 04 mode.

#12 6 years ago

HDF

HD_Fatboy

Pinside member

Wilcox, PA

6y 36,550 531 4

Quoted from SilverballSleuth:
steve_pbh - have you come to a solution? I brought home a Comet today and all coils will not fire, except for flippers. I'm also stuck in 04 mode.

Try toggling off, on, off and back on pin rapidly to get out of 04 mode, and change your batteries.

#13 6 years ago

DAV

wayout440

Pinside member