Hello,

I'm in the middle of restoring a Williams Grand Prix and my biggest
problem right now is that the reset sequence is not completing and the
score motor goes on forever. Hope any of you EM wizards out there can
diagnose these events and maybe tell me where to look.

1. I power on the game
        a. Lock Relay fires and stays locked.
        b. "Game Over" lights in the backbox

... Here I'm having some problems with the credit counter (a coin drop
increases the credits, but also chimes a bell and increases the 1000
score wheel), plus, no matter how many credits I have I still can not
start a new game with the start button. More on this in another post...

2. I manually trigger the Coin Relay (which should trigger the reset
sequence)
        a. The score motor starts running
        b. The "No. 2/3/? Reset" relays in the backbox fires in a pattern with
the two leftmost firering at the same time, alternating with the
rightmost. This resets all the score wheels to 0000000 where they stop.
        c. After a second or so, the Game Over Relay Latch is fired, and  "Game
Over" is no longer displayed in the back box. Instead the ball number
and player up is lit. Player up is 1.
        d. The Target Relay is fired and locks
        e. Both Bonus Steppers under the playfield locks the reset coil, and
sporadically fire the step down coil (step to 0 because of the reset
coil locked).
        f. The two kickers to the left and right of the playfield fire and kick
        e. The target relay is de-energized and the whole sequence from d is
repeated.

I've opened and cleaned the two bonus steppers, and I'm fairly sure that
the two player steppers (backbox and bottom cab) are zeroed. Same with
ball count which displays 1. And all the score reels are zeroed. So it
seems that everything is zeroed, but this is not passed on to the part
supposed to stop all this noise :) Is this possible? Also, what has the
Target Relay got to do with anything? Seems like it's firering in every
little sequence I've tried.

Thanks for any help I can get!

Tor Arne

Pictures to the question at http://williamsgrandprix.blogspot.com/

Tor Arne

after you reset the machine and all score relays are zero pull your
reset relay back to de- energized position. if it stays in that
position when you let go then the machine should play. if it does not
stay in that position then check your coin mech and front door. .your
welcome to emal me at brs...@yahoo.com if you need any help. norm in
missouri

Grand Prix - great EM game when the ball rips through the spinner and
the playfield lights run up.  The reset problem could be two problems.
I believe on the score reel switch stack there's '0 index' AND a run
score motor switch.  They should stay in sync (open/close).  Also, look
at the A,B,C,D drop targets and make sure their switch is closed when
target is in the up position.  Really need the schematics to see the
other switches that factor into the score motor running.  Keep at it -
you'll get it soon.

billg

you need to pull the main board out and inspect all contacts. Keep the
coin door plug unplugged also when testing(you have to put a jumper in
to complete a/c circuit.)
I also think you can disconnect the playfield from main to help trouble
shoot. I think also you can have the main board all by itsself powered
up and reset it that way also to help isolate the problem.

DONT GIVE UP! You will figure it out. I would start with only the main
board by itsself (with jumper for a/c) and trip the "player reset"
relay to test. I t should reset and motor should stop.

Grojohn

A/c jumper  should be top two plugs (blue and red I think) on coin
connector

All right,

Thanks for the answers Norm, Billg, Grojohn, Dale, Nick and everyone
else! Your help is really appreciated! :)

Today the manual and schematics finally arrived at my friends place in
Boston, US. He will scan them and e-mail me the crucial parts so I have
something to work with. First thing I got was the reset sequence which is:

---------

    1. Credit unit reset coil is energized by switch on reset relay,
thru score motor index cam switch A, credit button, zero switch on
credit unit, and switch on game-over relay or coin unit last position
break switch.

    2. End-of-stroke switch on credit unit reset coil will energize coin
relay.

    3. Switches on coin relay will run score motor, trip game-over
relay, and energize reset relay.

    4. Switches on reset relay will open circuits to playfield switches
and outhole relay, run score motor, energize reset coils on coin
unit-ball count unit-player unit and game-over relay, pulse no. 1, no. 2
and no. 3 reset relays, and reset left & right bonus units to zero.

    5. Switches on no. 1, no. 2 and no. 3 reset relays, will pulse the
(20) scoring drum units until they reach zero.

    6. When reset delay drops out, outhole relay is energized thru zero
switch on left bonus unit, switch on alternator relay, outhole switch,
delay relay and index cam switch ‘C’

    7. Switches on outhole relay will run score motor, pulse both bonus
unit S.U. Coils, and pulse ball release coil to propel ball toward plunger.

----------

So today I had something to work with. First, i unplugged everything
from the main board (backbox, coin door, playfield, power-switch and
chimes). Then powered up and manually tripped the Reset Relay. What
happened was:

     * Score motor starts running
     * Game over latch fires and holds
     * The coin unit and ball unit (steppers) fire their reset coil
     * The motor stops and the reset relay is de-energized.

So far so good, this should indicate that the problem is not with the
main board, right? It also fits with the reset sequence from the manual.
I also tried tripping the coin relay, which is one step before the reset
relay in the sequence, and same thing happens.

Then I connected the playfield. Still everything fits with the sequence
in the manual, bonus steppers are reset and the motor stops by itself,
BUT, one thing that doesn' happen is the point where the reset relay
de-energizes and the outhole relay is energized, causing a new ball to
be pushed to the plunger (6) Tripping the outhole relay manually does
exactly as the manual says (7), so somewhere between the reset relay
de-energizing, and the outhole relay firering there is an error.

I will name this "The Outhole Problem" for now :) Maybe this happens
because the backbox is not connected? I'm not to sure where the "switch
on alternator relay" is. Is it on the Altenator Unit (main board), or on
the Alternating Relay (playfield)? And the "outhole switch"? All I can
see is an Outhole Relay. I guess the " index cam switch ‘C’." is on the
score motor, but it's hard to tell where as I don't have the manual
pages for that part yet.

Anyways, I momentarily gave up after checking the obvious stuff, and
connect the backbox. Now I got the old problem with the reset relays
firering in the backbox, causing all score wheels to 000000, but no
motor stop. So, the old problem, "Score Reels From Hell", is probably in
the back box? I try to force the reset relay to de-energize and that
stops the motor, but also leaves a wheel coil in the back box energized.

I will try to clean every single one of those darn score wheels tomorrow
and see if that makes any difference. But one thing puzzles me. One of
the reset switches on each and every score wheel is always "connected",
or, at least it beeps when I put my multimeter to it. This is the top
switch in the picture at http://williamsgrandprix.blogspot.com/ Is this
correct? This is also present on the Alternator Unit on the main board,
which switches a switch on and of with every fire of the coil. Though
the switch beeps in both positions. A short somewhere, or expected behavior?

Thanks to anyone who bothered to read this far! If you have any idea why
all of this is happening, please let me know with a reply or a comment
at my project page at http://williamsgrandprix.blogspot.com/

Tor Arne

I did it! :) Thanks to you guys! And some nice schematics I got hold of
last night ;)

"The Outhole Problem" was due to the simple fact that I didn't manually
trip the outhole switch  :)

I also decided to go through the whole backbox and clean and
adjust/check every single one of those damn score reels. After 10/20 I
plugged it in and it worked! :) Score motor stops and Outhole relay is
triggered and the whole reset sequence completes! Hurray!

Now is testing all the targets and game rules.

I will be back :)

Tor Arne