(Topic ID: 215547)

Black Belt - Solenoid Expander Board - Lights Cause Solenoid Twitch

By hellfaust

4 years ago

Topic Stats

  • 8 posts
  • 3 Pinsiders participating
  • Latest reply 4 years ago by Inkochnito
  • Topic is favorited by 1 Pinsider


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seb (resized).png
BlackBelt (resized).jpg

#1 4 years ago

Greetings, I was wondering if anyone can shed light on this issue.

On a Bally Black Belt (6803), most solenoids controlled by the Solenoid Expander Board are experiencing twitching (slight short movement and/or slight short buzz) when related components are activated.

Example 1:
Flashing the Man Bright Lights unexpectedly causes the Left Drop Target Reset solenoid to twitch.
The reverse is not true: activating the Left Drop Target Reset solenoid does not flash the Man Bright Lights.
Note: Transistor Q16 is used to activate both.

Example 2:
Flashing the Sun Bright Lights unexpectedly causes the Right Drop Target Reset solenoid to twitch.
The reverse is not true.
Note: Transistor Q15 is used to activate both.

Example 3:
Flashing the Right Bright Lights unexpectedly causes the Middle Saucer to twitch.
The reverse is not true.
Note: Transistor Q18 is used to activate both.

There is another pair of components controlled by the Solenoid Expander board that doesn't seem to exhibit the problem. Flashing the Top Left Lights does not cause the Right Kick Back to twitch and vice versa.

Here is a video of the behavior:

In the video, depressing a Lane Return switch causes the Man Bright Lights to flash seven times as expected. But accompanying each flash is a visible and audible twitch of the Left Drop Target Reset solenoid. So the solenoid twitches seven times. And it is twitching, not being fully activated.

The problems in examples 1, 2 and 3 are reproducible during the solenoid self-test.

Also, self-test shows that the Solenoid Expander Board (SEB) is operating nominally: relay clicks on/off and accompanying 555 lamp flashes on/off.

Is it likely to be a faulty Solenoid Expander Board?

Is it likely that the switch contacts on the Solenoid Expander Board's relay need filing/replacement?

If anyone has any suggestions at all, please let me know.

Thank you.

#2 4 years ago

Love to know the solution as well — my parents bb I grew up playing has same behavior. Never had time to diagnose it. Assumed it was bad diodes possibly. The right and left resets go crazy during belt awards for like 5 seconds or more because of this issue.

#3 4 years ago

Check out the diode's in the circles.
Those are the blocking diode's.
WHen one of them is broken (shorted) this can happen.
Because of the lamps and coils being in series when this happens, causes the coils to twitch and not completely activate.


BlackBelt (resized).jpg

#4 4 years ago

Here are the results (forward bias/reverse bias) of the diode (1N4004) tests:

Man Bright Lights diode: .452V/OL
Sun Bright Lights diode: .448V/OL
Right Bright Lights diode: .457V/OL
Top Left Lights diode: .477V/OL

Left Drop Target Reset diode: 0.491V/OL
Right Drop Target Reset diode: 0.496/OL
Middle Saucer diode: 0.467V/OL
Right Kick Back diode: 0.486V/OL

I believe these are OK based on 1N4004 silicon diode specs:

Good Forward Bias: 0.5-0.8V
Good Reverse Bias: OL
Shorted: 0V-0.4V in both directions

#5 4 years ago

I investigated the Solenoid Expander Board (SEB) further.

With SEB inactive:

SEB J1-7 = 43V
SEB J1-4 = 43V
SEB J1-5 = 46V <----- Should be 0V!

With SEB active:

SEB J1-7 = 0V
SEB J1-4 = 43V
SEB J1-5 = 43V

Next step is to swap the SEB.

seb (resized).png

#6 4 years ago

Look for a short between the wire at J1-5 and J1-4.
Maybe a solder bridge when you reflowed the board?

Look for a connection to the Black-Blue (82) wire from any other wire at these coils.
Maybe a diode on a coil connected in reverse?
Like you say, J1-5 should be 0V with SEB inactive.
Find the power source to the Black-Blue (82) wire.

Disconnect the connector at the SEB and see if you still have the odd 46V.
If yes, check the affected coils and lamps.
If no, inspect the rest playfield.

#7 4 years ago

Disconnected connector at SEB and still had a (smaller) voltage on Black-Blue.

Finding the phantom power source to the Black-Blue was paramount.

Checking and doublechecking revealed that the Right Kick Back coil blocking diode was missing (see image).
And the coil lugs were wired as if the diode was not even in the schematic.

Adding the missing diode and rewiring coil lugs correctly resolved the issue

Maybe somebody replaced coil in the past and put it back incorrectly.

Thank you Peter for your excellent advice.

bbfix (resized).jpg

#8 4 years ago

You're welcome.
Most of the time this is the problem with phantom activations.

Short story, wroung replacement coil used at the Right Kick Back.


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