(Topic ID: 102873)

Black Knight Drop target bank solenoid not working

By 04barb

4 years ago

Topic Stats

  • 7 posts
  • 5 Pinsiders participating
  • Latest reply 4 years ago by Toyguy
  • No one calls this topic a favorite


Linked Games

#1 4 years ago

On Black Knight, the upper playfield right drop bank solenoid isn't working. I tested the solenoids in solenoid test mode and its #5 on the test because when it reaches #5 nothing fires. I tested the solenoid and it fires when I ground out the metal transistor. I replaced the diode on the solenoid even though it was fine. I tested the transistor and pre driver transistor as well as the 7408 chip. Everything tests good. What can I check next? I don't think its the PIA chip because if that chip was bad it would cause other issues other than this?

#2 4 years ago


A transistor can test good but fail under load.

Do you have a multi-meter?


OK, that's a dumb question. Of course you do to perform the test you mention.

SO, connect meter black lead to ground and put red lead on the connector pin feeding ground (on signal) down to that solenoid. In solenoid test, you should see solenoid B+ voltage until it is supposed to fire, then the value will pulse low for a half second. If you need to, verify the test by probing a working solenoid to see the behavior you should be seeing.

#3 4 years ago

Check the simple stuff too, like continuity of the wire, cracked solder joints at the header...

#4 4 years ago
Quoted from LEE:

Check the simple stuff too, like continuity of the wire, cracked solder joints at the header...

That stuff has been proven good already by the tab-grounding test. (no offense intended)

#5 4 years ago

I replaced the TIP 102 and its pre driver transistor. That fixed the issue. But when I reinstalled the game boards after soldering I noticed that now the lower right drop target bank solenoid isn't working when it was working before. Here is the back story: when I was testing the game when I first bought it, it was missing the blanking signal because I had accidentally cut the line. So I blew through about 10 fuses that control the solenoids before I decided to fix the blanking signal. I think what happened is that by blowing through those ten fuses it stressed all the transistors on the driver board that control the solenoids because when the fuse blew it locked on every solenoid before it blew for a second or two. Now the transistors are going one by one as they are used.

#6 4 years ago

It doesn't take very long to test the transistors, it very likely that others have been stressed down the line. When fixing one it can cause others to fail, or show that they have failed.

#7 4 years ago

Given the serial nature of the failures and the generally accepted lifetime of the 40-pin connector at about 25 disconnect-reconnect cycles, you're probably well advised to replace all of the drivers and pre-drivers at one time and get it over with!

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