Trouble with Black Knight

[JONTHEBOMB]

At the end of August a transistor (Q19) fell off the Driver board.  Before the transistor is soldered back on to the Driver board I would like to check if it is any good.  So, the first question is how do I use a multimeter to check if the transistor works?

Another problem that I believe is related to the transistor falling off is the lower right 3-bank drop targets were not dropping when the ball hit them.  I found under the playfield solenoid 3 resets the drop targets and can only move half way up before it gets stuck.  If I am reading the manual right the transistor (Q19) is used for solenoid 3 drive.  Second question if the solenoid cannot be repaired do I just need to buy a new coil and replace the old one?

While looking around in the machine I checked the fuses on the power supply board and found the solenoid fuse (F2) was a 5 amp slow blow when the manual shows a 2.5 amp slow blow.   

Third question what are the correct values for the fuses on the power supply board?

I found a guide online states:
•   F1 = Score display 90 volts AC, .25 amp Slow Blow.
•   F2 = Solenoids 28 volts DC, 2.5 amp Slow Blow.
•   F3 = Lamp matrix 18 volts DC, 8 amp Fast Blow.
•   F4 = Flippers 28 volts DC, 10 amp (2 flippers) or 15 amp (3 or 4 flippers) Fast Blow (on shuffle alleys this is the GI fuse). This fuse is NOT used on Firepower2, LaserCue, Starlight.
•   F5 = 9.3 volts AC (input for +5 volts), 7 amp Slow Blow.
•   F6 = 9.3 volts AC (input for +5 volts), 7 amp Slow Blow.
•   F7 = General Illumination for pinballs, 6.3 volts AC, 20 amp Fast Blow.

The manual agrees with F1 – F3 and F7.

Manual states:
F4: 20 amp fast blow
F5: 7 amp fast blow
F6: 7 amp fast blow

[ChadTower]

What does "stuck" mean here?  Does that mean it has the power to fire further but is physically jammed?  Or does it mean that it only fires up that far because it's not strong enough to go further?

How are you firing the coil to get it that far?  Is that fired through the coil test, by a game action, or by shorting the coil to the rail?  Keep in mind on sys7 games the coil test doesn't pulse long enough for some of the coils to fully extend and so they won't reset the drop banks.  It tests the CPU control but not really the power.  You have to manually short those coils to test full strength.

Hard to say yet if you need to replace the coil - if it got fried by overfusing, maybe, but instinct is telling me that isn't the problem here.  First thing you do before anything else is replace that fuse with a properly rated on and check every other fuse in the game.  Odds are there are others also overfused.  What guide are you looking at?  Is that Clay's?  I would go with the manual in a mismatch.

[Q*Bert_OP]

...drop targets were not dropping when the ball hit them...solenoid that resets the drop targets and can only move half way up before it gets stuck. 

Your coil locked on, causing the targets to not drop, and burn up the coil. The transistor shorted and got very hot but doesn't sound like it blew a fuse. Your transistor that "unsoldered" itself from the board is shorted and would be damaged by the heat anyways. Replace the coil and it's sleeve, and put in a new transistor. Check to make sure your game isn't overfused anywhere.

[JONTHEBOMB]

I removed the entire drop target/solenoid assembly.
 

What does "stuck" mean here?  Does that mean it has the power to fire further but is physically jammed?  Or does it mean that it only fires up that far because it's not strong enough to go further?

The metal plunger moves up smoothly until the halfway point.  After the halfway point I can give the plunger a good push to get it all the way into the coil.  Once the plunger is in the coil it is stuck and does not fall down.  The plungers for the other three drop target solenoids fall down smoothly with gravity.  I think the plastic sleeve expanded a bit, which is preventing the plunger from moving in and out smoothly.

How are you firing the coil to get it that far?  Is that fired through the coil test, by a game action, or by shorting the coil to the rail?  Keep in mind on sys7 games the coil test doesn't pulse long enough for some of the coils to fully extend and so they won't reset the drop banks.  It tests the CPU control but not really the power.  You have to manually short those coils to test full strength.

The coil was fired just by normal game action.

Hard to say yet if you need to replace the coil - if it got fried by overfusing, maybe, but instinct is telling me that isn't the problem here.  First thing you do before anything else is replace that fuse with a properly rated on and check every other fuse in the game.  Odds are there are others also overfused.  What guide are you looking at?  Is that Clay's?  I would go with the manual in a mismatch.

The guide is found here:
www.bigdaddy-enterprises.com/pdf/Williams%203-7%20Fuses.doc

One quick note: Tested diode on coil and it was good.

[JONTHEBOMB]

Your transistor that "unsoldered" itself from the board is shorted and would be damaged by the heat anyways.

What would cause the transistor to short?  Too much current caused the material to breakdown?  Age?


Found some cracks in the transistor.

[ChadTower]

^^^^^^^^^^^

Pretty much.  That's where I was leading to with those questions.  I disagree on the fuse, though.  200% of rated current does make a difference.  IMO you don't even need a grinder to smooth out the plunger end.  A small metal file will do it.

The tricky part here might be replacing that transistor.  That's a pretty crowded little area on Sys3-7 and the pads are as small as possible.  Odds are they are gone and you'll have to run at least one jumper.  Fortunately the traces in that spot are only on one side of the board. I had to do the same thing on my Black Knight and would swear I posted a pic of it but it isn't there.  I must have taken it and forgotten to add the pic... and coincedentally enough my notes say it was also Q19.  I can hunt down that pic tonight if you want.

[JONTHEBOMB]

2 - measure the resistance across the lugs on your coil.  Then measure another coil with the same part number in the game that you know works.  If it's within 10%, your coil is good.  If it's not, replace it.

Measured resistance coil is still good.

3 - if the coil is good, check the mechanical action of your plunger.  Is the end of the plunger deformed?  If it is, get out the bench grinder and smooth it down.  Follow that with some sand paper (I usually lightly sand problematic plungers anyway, just wrap sand paper around it and spin it around a little).

Tested plunger in another coil and it moved smooth as butter. 

Removed the plastic sleeve from the coil, cracked it a bit.  It's obvious that the sleeve is preventing the plunger from moving smoothly.  I think a drill will crack/destroy the sleeve, so it is going to be replaced

The tricky part here might be replacing that transistor.  That's a pretty crowded little area on Sys3-7 and the pads are as small as possible.  Odds are they are gone and you'll have to run at least one jumper.

Fortunately the pads are still on the board.

[ChadTower]

Is the sleeve filthy or melted?  I don't think I have seen a still good coil with a melted sleeve.

[ChadTower]

Yeah, maybe.  The ones I have seen are melted, not what he's describing.

[JONTHEBOMB]

Is the sleeve filthy or melted?

The sleeve is dirty, cracked a bit and does not fit properly in the coil.  I had a hard time getting the sleeve out of the coil, it was stuck in there good. When the plunger was tested I could easily move the sleeve in the good coil.   Also, the plunger can not go in and out of the bad sleeve smoothly.  I think there was enough heat to cause the sleeve plastic to expand, but not enough to melt it.  The transistor and other pinball parts should be here in a couple of days.

[JONTHEBOMB]

Replaced fuses:
1 Amp changed to 0.25 Amp
5 Amp changed to 2.5 Amp
10 Amp changed to 7 Amp
5 Amp changed to 4 Amp

Replaced transistor and installed a new coil since the new sleeve didn't fit in the old coil.  At some point I will drill out the old coil so the sleeve will fit and save the coil as a spare.  Tested Black Knight, transistor is staying put and drop targets are working. 

More problems to fix:
- Left magna save is getting weak most balls roll past it.
- Left upper playfield flipper weak.  (I think it needs a rebuild kit.)
- Last chance switch on right side.  (has never worked)
- Sound issue (Sometimes the machine plays only wrong sounds.  For example if I get multiball Black Knight will play the spinner sound effect.)