Sunday, April 4, 2010


When I started my machine, the knocker would knock for or five times and then I would get a message telling me to adjust some switches.  In my case they were the pop bumper, the right sling, and the right flipper.  I had rebuilt the right flipper and I knew the switch was good, so I was a little worried about a more serious problem.

In the Pinrepair guide, they have a really detailed writeup about the switch matrix.  I wont try to reproduce that.  I'll just say what I did to fix my problems.

First, I did what the manual suggests, test the switches at the main board first to make certain it's a wiring problem and not a main board problem.  Using the matrix in the documentation, I identified the two pins I needed to jumper.

Here you can see a few things about the switch the system was saying to check.  It's on 1J10, pin 2 and 1J8 pin 2.  While in test mode, I should be able to connect those two switches and have the system tell me that the switch is closed.  Also, you can see they identified the color of the wires.  There should be a White/Violet and a Green/Red wire connected to the switch.

I jumpered those two here:

The result:

Phew, the board is OK.  I checked the other two switches on the board and they were fine too.  It was definitely a problem in the wiring somewhere.

After that, there isn't much to it.  The matrix lays out each point those wires touch.  I had to check the whole chain to see what I could find.  Having never done this before, I didn't choose the most efficient way to go about this, but it worked out OK in the end.

I connected one end of my continuity tester to the first lead in the chain for the white / violet chain.  The slam tilt.  I checked each point along the way, Slam tilt, Right Flipper E.O.S., Right Center Eject, Middle Ramp, etc... and found that I had continuity end to end.

It didn't take long on the Green / Red chain.  Here is what I found when I got to one of the ball trough microswitches:

I soldered the wire into place and it started registering in test mode!  One fixed and two to go!!

I checked continuity through all of the other chains and found the wiring to all be intact.  I went from point to point, but I could have just checked continuity between one end and the the other in the grid to see if the wiring was all in tact.  If it wasn't in tact, I would have to check them all one at a time anyway so I didn't see the harm.  Also, I was learning A LOT and I really wanted to check every point just to see how it was done!

One end of the chain, the right coin switch:

The wiring was OK, so I checked the switches themselves.  If I was interested in solving the problem as quickly as possible, I should have done that first.  This was an exploration too, so it was OK.  But take note of that, first check the switches.  (Also, I started with the flipper switch which I was certain was OK...)

Pinball machines us a lot of these leaf switches.  Sometimes they need to be tweaked a little.  First, get yourself something non-conductive to check the switches.  I have a couple of long wooden coffee stirrers that I grabbed when I bought a cup of coffee at a big coffee chain that rhymes with "Starbucks"...

I don't like poking around with the machine on, but sometimes you have to.  Here's something bad that can happen according to

"When in a hurry, many make an under playfield adjustment with the game turned on. Doing a switch adjustment with the power on could easily short a coil lead (+25/50 volts) to a switch lead. This will immediately blow the switch matrix, and can fry most anything up to and including the 6821 PIA at U38."

So, don't do that.  Be careful.  Don't poke around with a screwdriver.  I only use the stick to close or open a switch in test mode -- Never to make an adjustment.  Adjustments are made with the machine off and using a neat little tool I got from Pinball Life.  (Ultimate Leaf Adjuster Tool - Worth the $7.)

Making an adjustment to the slingshot bumper switch.  It's MUCH easier with the right tool.  When I bought this tool, I didn't need it for anything at the time.   I just figured it would probably be something I needed someday.  I've been working on this F-14 for 3 or 4 weeks now and I've used it 10927150915 times.

I tweaked both switches and now I don't get any warnings at start.  What is funny is that you can get these warnings when everything is working just fine.  These switches are in place to audit how often each of these flippers, pop bumpers, trough switches, etc actuate.  If a switch isn't activated more than (I think it said 50) times in some period of time, the game things something is wrong and warns the operator.

In this case, the system in place to warn me about problems actually was the thing with problems.

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