(Topic ID: 299146)

Pinbot; no Knocker

By bigjimm64

2 years ago



Topic Stats

  • 5 posts
  • 2 Pinsiders participating
  • Latest reply 2 years ago by KJL
  • No one calls this topic a favorite

You

Linked Games

Topic Gallery

View topic image gallery

A C Select (resized).png
pasted_image (resized).png

#1 2 years ago

Hey all,
I have gone as far as my abilities will allow me on an issue I'm having with a Pinbot. I cannot figure out why the knocker coil will not fire.
I have checked the ohm's of the coil, 4.2, so that looked good. I snipped the diode and it checked out ok and it is orientated with the band facing the black/brown wire. I'm getting a voltage reading on both lugs of the coil so no broken internal winding. The out hole kicker that shares the same transistor is working, so no issue there.
When I put the coil in test, the GI lights dim slightly when it is trying to fire the knocker. I'm wondering if I have a broken wire somewhere but I cannot determine from the diagram what wires are supposed to be where. The black/brown I see goes to one lug of the coil with an orange on the other side. The orange, I assume, is a common ground? Maybe it would help if someone would explain how to read the wire color and connections diagram.

pasted_image (resized).pngpasted_image (resized).png
#2 2 years ago
Quoted from bigjimm64:

Maybe it would help if someone would explain how to read the wire color and connections diagram.

Orange is probably power and should always be on in game if that side of the relay is connected. The black brown and violet brown wires are the wires the transistor connects to ground when the CPU decides to fire the solenoid/flasher. So the solenoid/flasher always has power and then fires when connector to ground.

When they tell you a wire color it should be the drive/ground wire on the coil (not power) and go to the connector on the board usually. But in this case where one transistor drives 2 solenoids/transistors the color at the coil isn't always the color at the board as it has to connect to 2 wires.

I haven't had to fix this AC select issue in a few years but you noted that one transistor controls 2 solenoids the A side and the C side. Usually cols that are used a lot are on the A side and things like flashers and knockers that don't impact game play if they are late are on the C side.

The CPU fires the AC Select transistor to switch between the A side and C side then fires the same transistor but when the relay is on the C side is connected to Edit It connects the C side (orange) to power instead of the A side Power

Do any of the solenoids/flashers that are on the C side work? If yes trace the black brown to see if it is broken somewhere.

If not, suspect the relay or its controlling circuit. You should hear the relay click in solenoid test also. Look for the AC Select relay in the solenoid table and listen for a click when its number comes up.

Interesting that the GI dims when the knocker should fire. GI can also be controlled by relays but I don't know Pinbot to say whats going on there. Feel free to ask more questions.

#3 2 years ago
Quoted from KJL:

The black brown and violet brown wires are the wires the transistor connects to ground when the CPU decides to fire the solenoid/flasher.

So, theoretically, I could ground out the black/brown to a grouding strap and it should fire since there is voltage to the coil on the orange.

Quoted from KJL:

Do any of the solenoids/flashers that are on the C side work? If yes trace the black brown to see if it is broken somewhere.

Yes, all others work on the C side. The black/brown originates from a board under the playfield that has a bunch of diodes and it has continuity from the coil to that board.

Should the diode band be on the voltage side of the coil, the orange wire or the black/brown, the drive side?

#4 2 years ago

@bigjimm64

You should be able to put it into test and check power when the out hole is selected for test and test power when the knocker is selected for test. If the knocker has power then you can ground to test if the coil works.. Also pinwiki has good stuff. https://www.pinwiki.com/wiki/index.php?title=Williams_System_9_-_11

For diode orientation on the coil the band is to the power lug. If you have the diodes on a board check the schematic. It will also show you the path to ground to test if the coil works. Here is an example from a game I have on my computer.
A C Select (resized).pngA C Select (resized).png

#5 2 years ago

I now looked at the schematic and it looks like power is what is switched by the relay so I have faulty memory. Check that out in your manual. A side should have power by default and C side gets switched by the relay. See if that looks right.

Edit: I updated my previous post to be more clear how you can test the A side or the C side because normally the A side has the power when the relay is not engaged.

Promoted items from the Pinside Marketplace
From: $ 1.25
Playfield - Other
Rocket City Pinball
Other

Reply

Wanna join the discussion? Please sign in to reply to this topic.

Hey there! Welcome to Pinside!

Donate to Pinside

Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!


This page was printed from https://pinside.com/pinball/forum/topic/pinbot-no-knocker and we tried optimising it for printing. Some page elements may have been deliberately hidden.

Scan the QR code on the left to jump to the URL this document was printed from.