(Topic ID: 295364)

Ball release locking on

By Brewchap

42 days ago


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  • 28 posts
  • 4 Pinsiders participating
  • Latest reply 21 days ago by sataneatscheese
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#1 42 days ago

My ball release shorted out. I believe that this is solenoid one. I changed out Q15, Q14 and the coil. Now at boot up, the coil locks on. I thought that when you have a coil short out, that after you change out the coil, you change out the transistors to fix the problem. This is not the case this time unless I got the wrong solenoid.

#2 42 days ago
20210618_190823 (resized).jpg
#3 42 days ago
Quoted from Brewchap:

This is not the case this time unless I got the wrong solenoid.

I doubt you got the wrong one.

Diode on facing the right direction ? Bad coil ?

LTG : )

#4 42 days ago

BLUF: You have to change out the Solenoid and the Transistor at the same time.

Okay, I went nuts with something similar on my ST:TNG a few months ago. See https://pinside.com/pinball/forum/topic/sttng-owners-club?tu=sataneatscheese#op starting with post 5019 for my story.

What happened in my particular case was I plugged in a ribbon cable backwards briefly, which broke a transistor causing a solenoid to melt and short. When I replaced the solenoid, it melted the next time I turned it on because I had not fixed the transistor. So I replaced the transistor, but the solenoid was shorted out which blew the transistor. I went through this cycle a few times before someone pointed out that you have to change out the solenoid AND the transistor at the same time. Hope that helps!

#5 42 days ago
Quoted from sataneatscheese:

BLUF: You have to change out the Solenoid and the Transistor at the same time.
Okay, I went nuts with something similar on my ST:TNG a few months ago. See https://pinside.com/pinball/forum/topic/sttng-owners-club?tu=sataneatscheese#op starting with post 5019 for my story.
What happened in my particular case was I plugged in a ribbon cable backwards briefly, which broke a transistor causing a solenoid to melt and short. When I replaced the solenoid, it melted the next time I turned it on because I had not fixed the transistor. So I replaced the transistor, but the solenoid was shorted out which blew the transistor. I went through this cycle a few times before someone pointed out that you have to change out the solenoid AND the transistor at the same time. Hope that helps!

No, I did not do this. I tested the coil first before I changed out the transistors. I'll change out all three this time and see what happens.

Quoted from LTG:

I doubt you got the wrong one.
Diode on facing the right direction ? Bad coil ?
LTG : )

Yes sir, I believe that I got that right but may have messed up the coil during testing.

#6 41 days ago

I got 2 coils, one is the one that is locking up, and an extra, they both test 6 ohm on the fluke 177 meter. If remember correctly, this is good. Where to go now?

#7 41 days ago

I still have the same problem with both coils. But they ohm out at 6 ohms.

The problem happened after I cleaned the coil that was greased down and I put the terminals of the coil up which grounded out on the skirt. Something aint right in my troubleshooting.

#8 41 days ago

OK, I found another new coil. I also changed the transistors out along with the coil before I turned power on. It still wants to lock on at power up.

This time I changed out the driver board, and it works. What am I over looking from the one board to the other?

#9 41 days ago
Quoted from Brewchap:

What am I over looking from the one board to the other?

Something upstream from the transistor.

LTG : )

#10 41 days ago
Quoted from Brewchap:

What am I over looking from the one board to the other?

Lose through board continuity on one of the transistor legs ?

LTG : )

#11 41 days ago
Quoted from LTG:

Lose through board continuity on one of the transistor legs ?
LTG : )

Trying to wrap my head around this. Sorry. Maybe through the interconnect? Not sure how to check this. Leg not soldered on good?

#12 41 days ago
Quoted from Brewchap:

Trying to wrap my head around this.

The circuit board is made. Plain board with traces both sides. Then the board is lowered into a tank and the holes where the legs of components go are plated. This assures continuity of one side to the other for the traces if needed.

If the plating through the hole is damaged, just soldering a component in sometimes isn't enough. Like replacing large capacitors on a driver board. Often more damage is done than goo if you aren't skilled in board repair.

When I solder something into a board. I take a meter and check continuity of one of the legs of the component to a spot away from the repair area, along the same trace. To be sure continuity is good through board and across board.

One leg of the transistor open ( lost continuity ) can blow the transistor. I discovered this with a LOTR.

LTG : )

#13 41 days ago
Quoted from LTG:

When I solder something into a board. I take a meter and check continuity of one of the legs of the component to a spot away from the repair area, along the same trace. To be sure continuity is good through board and across board.

One leg of the transistor open ( lost continuity ) can blow the transistor. I discovered this with a LOTR.

Gotcha, I traced back as far as I could to check for continuity on each leg and they were good. I also changed out the resistors to be on the safe side. After installing the resistors, I ohm them out and R29 keeps reading a high resistance compared to the same resistors for other solenoids. This makes me wonder if IC1 (7408) is bad.
I feel like I am over thinking things, but this is not a simple transistor change from what I have done in the past.

#14 39 days ago

Well, I replaced IC1 and still have the same problem. Q15 and Q14 still test good. For good measures, I changed out the solenoid PIA. That didn't help either. I tested IC7 and IC9. They tested good also.
I'm not finding a smoking gun on this issue.

#15 39 days ago
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#16 38 days ago

I tested with another driver board and the ball release works as it should. So that tells me that I have a board problem and not a wiring problem.

#17 38 days ago
Quoted from Schwaggs:

Pull the solenoid fuse so the coil does not energize.
Power up the game and connect your logic probe.
Probe the AND gate that drives the Ball Release solenoid.
IC1 pin 9 is blanking input (should be HI if all is well)
IC1 pin 10 is the input from the PIA and it should be LOW when the solenoid should be off and flicks HI when the solenoid is activated (you can use solenoid test to activate it if you want)
IC1 pin 8 is the output - it should be LOW when the solenoid is off and HI when it is on.
If IC1 pin 8 is reading low, and the coil is still locking on, you have a bad pre-driver transistor or a bad driver transistor or both. (most likely the cause)
If IC1 pin 8 is reading HI when IC1 pin 10 is LOW - IC1 is bad. (less common)
If IC1 pin 10 (PIA input) is locked HI - you have a bad PIA (rare)

https://pinside.com/pinball/forum/topic/firepower-ball-through-coil-locking-on#post-5704680

Well, IC1 pin 8 is low. So that puts me back to the pre-driver transistor and driver transistor. And I just changed them out again. Back to testing the traces again I guess.

#18 38 days ago

sataneatscheese, I invented this technique and phrase way back in 1991....true story.

#19 38 days ago

Have you compared the output of IC5, pin 2, to pins 3 and 4?
IC5 is a 6821.
--
Chris Hibler

#20 38 days ago
Quoted from ChrisHibler:

sataneatscheese, I invented this technique and phrase way back in 1991....true story.

What does BLUF stand for?

#21 38 days ago
Quoted from ChrisHibler:

Have you compared the output of IC5, pin 2, to pins 3 and 4?
IC5 is a 6821.
--
Chris Hibler

I'm not sure how your wanting me to compare the output of the pins, so I used the logic probe. All showed LOW

#22 37 days ago
Quoted from Brewchap:

I'm not sure how your wanting me to compare the output of the pins, so I used the logic probe. All showed LOW

Yes. With logic probe.
Pins 2, 3, 4 all showed low even though coil 1 was locked on?
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#23 37 days ago

Yes sir. I had the solenoid fuse pulled though.

#24 37 days ago
Quoted from Brewchap:

Yes sir. I had the solenoid fuse pulled though.

OK. Good. I'd rule out the 6821 then.
I'd leave that fuse pulled, and probe the downstream circuit, comparing results between the equivalent points between solenoid 1 and 2 circuits.
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#25 37 days ago

I found that the solenoid 1 IC1 pin8 was low.
For solenoid 2 IC1 pin11 was low also. So this should rule out IC1.

Next in line is the resistors. Solenoid 1 R29 is high on both sides of the resistor.
Solenoid 2 R32 is low on both sides of the resistor.

Everything after IC1 is difference from one another.

I pulled the 2n4401 for solenoid 1, just to see if it would influence the reading for R29. the resistor still test high on both side so I am going to pull it. .

#26 37 days ago

Well, strike all the above info that I wrote. Using the logic probe made me take a close look with a magnify glass and I found that I was looking at IC1 wrong. Testing the real pin 8 showed high. So I got a bad 7408 chip.

2 weeks later
#28 21 days ago
Quoted from Brewchap:

What does BLUF stand for?

BLUF: Bottom line up front.

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