Re: Need help understanding an EM schematic

On May 19, 5:41 am, seymour-shabow <seymour.sha...@xxxxxxxxx> wrote:
Jerry wrote:
First question: why does SB1 have no coil?  Is it just due to a
physical limitation to the number of switches that can run off one
relay (SB2 in this case)?
Second question:schematicshows the machine in a reset state, ready
for player to shoot 1st ball, _line cord unplugged_.  Doesn't that
kind of make things a little more complicated?  Since any energized
relays (except those in the control bank) will open their switches
once power is cut.  Or does it imply that no relays are active before
it is unplugged?  That is, plugged/unplugged states are identical?

Not if there are some locking relays in there - the locking plate will
engage and even if you cut the power, they will stay engaged.  The
reason they say this is what the switches are at that point is that they
need to get the machine into a known state, or troubleshooting would be
even harder.

Right, that's why I mentioned the control bank. Are there other
locking relays besides those? And I get the benefits of the known
state. I just wasn't sure how unplugging the power added to the known
state already specified by the "player 1, 1st ball ready to be
played".


The motor still mystifies me.  I understand what switches correspond
to the different positions, but can't make heads or tails of the
sequence chart.  I mean yeah, wherever there's a black bar, it means
the switches at that motor position will be activated when the motor
reaches that rotation, but I have no idea how to relate different
lines in the chart to actual events.  And what's that picture of the
part with the "S" and the "L" on it?

That's the score motor, the S and L refer to short and long positions on
the switch followers - they tweak the timing as the switches pass the
cams on the score motor (don't change these!!!  They're a pain in the
ass to keep in place while you're tightening the switch stack.)

Ummm, nope, not visualizing this.


Think of an old time cash register, you punch numbers into it and then
have to pull the handle to 'do' the work of adding them.  The punching
the #'s part is the relays, and the pulling the handle is the motor
turning.  There's a ton of circuits on the score motor, but only certain
ones do anything each cycle depending on what relays are activate when
the score motor runs.

I understand the theory. It's just hard to see a line in the sequence
chart, 2B, say, and figure out what the activated relays are that will
be triggered by the motor switches at that position.


One thing I've found to make it easier to troubleshoot anEMis to look
at the lamps, if you figure out what lights a feature it's usually the
same relay for the other functions.  Keep in mind also that you will
have different switches in the stack for each part of the feature; i.e.
one switch pair lights the lamp, one switch pair is activate so that
when the feature is scored, it scores properly.  For instance, on fast
draw you have A-B-C getting scored and the eject holes score 1000+ 1000
for each letter lit.  So when A is active it adds a circuit to the score
circuit for the hole - which lets one of the 'add 5' cam levels on the
score motor score the 1000 points.  There's always one "add 1000" active
for the eject, and one is added for each of A, B, and C.  They are
actually all separate circuits with their own wires, etc.

I need to study the schematic some more, so I can attach functional
labels to the different motor positions.

Thanks for the explanations Scott, they are helping despite my voicing
the parts I still don't understand.

-Jerry
.

Relevant Pages

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  • Re: TEAM-EM Tech Q GTB Fast Draw
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  • Re: Need help understanding an EM schematic
    ... physical limitation to the number of switches that can run off one ... Or does it imply that no relays are active before ... That's the score motor, the S and L refer to short and long positions on the switch followers - they tweak the timing as the switches pass the cams on the score motor (don't change these!!! ... So when A is active it adds a circuit to the score circuit for the hole - which lets one of the 'add 5' cam levels on the score motor score the 1000 points. ...
    (rec.games.pinball)