Tech: Coil stuck on

[Guest]

Archived from groups: rec.games.pinball (More info?)

Ok here's the story. I have a "Fire" pin that the upper left
slingshot did not work. I checked the coil and it had the proper
voltage and it would work when I grounded it out. I have continuity
from the driver board to the coil but neither the coil or the sling
switches work in test mode. Well I jumped the slingshot switches with a
piece of wire and must have shorted something out because now in
addition to the original problem the left lower slingshot coil is stuck
on. I replaced the coils to both slingshots and the guide said to
replace the corresponding tip 122 transistors in the driver board,
which was done.But the lower left slingshot coil is still stuck on and
the original problem of the upper slingshot not working is still there.
Any suggestions on a fix for one or both of these problems would be
appreciated. Thanks in advance

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

First off, it was unnecessary to replace the coil since it worked when
you grounded the coil. Did you also check the wiring by grounding the
tab on the driver transistor?

You very often have to replace the pre-driver transistor as well when
you replace the Tip122, find and replace this one also (hopefully you
did not fry the tip122 you just put in).

If you sent coil voltage through your switch matrix you will have some
more troubleshooting to do first. Pull the solenoid fuse out so the
coil does not lock on and see if you can get any switches to work in
test mode. You might have some PIAs fried that will need to be
replaced, do you have the schematics? You will have to trace the
signals back to find the associated chips that may also be bad at this
point.

It might be worth it to stop and send the board out to someone to have
it fixed, the marvin guides are good but if you are not experienced,
you could continue to make the problems worse.

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

Both of these coils are part of the "special" solenoids section on the
driver board- 6 or 8 coils that are directly driven by switch input-
typically slingshots and pop bumpers in most games.

At first, I would have suspected a bad switch or signal to/through the
switch, but with the thing not firing in test, and the subsequent problem
with the other sling, it sounds like you've got a low-level circuit board
problem on the driver board.

Don't waste your time and money replacing solenoids- the advice you got for
that is nonsense. Replacing a solenoid for a problem/symptom like this is
like replacing the engine in your car because you're out of gas. It won't
make any difference.

Most likely your problem is in the low-level logic circuitry on the solenoid
driver board- bad 7408/7402 gate or PIA chip (or both). At this point, I
would enlist the help of a qualified circuit board repair person to properly
diagnose and repair this- it sounds very low-level to me- not something as
simple as a bad coil, switch, broken wire, or bad driver transistor.

Ray J.
--
Action Pinball & Amusement, LLC
Salt Lake City, Utah USA
Web: www.actionpinball.com

We're serious about pinball. Anything else is just for fun!



<fwfd394@aol.com> wrote in message
news:1127229270.020309.23180@g43g2000cwa.googlegroups.com...
>
> Ok here's the story. I have a "Fire" pin that the upper left
> slingshot did not work. I checked the coil and it had the proper
> voltage and it would work when I grounded it out. I have continuity
> from the driver board to the coil but neither the coil or the sling
> switches work in test mode. Well I jumped the slingshot switches with a
> piece of wire and must have shorted something out because now in
> addition to the original problem the left lower slingshot coil is stuck
> on. I replaced the coils to both slingshots and the guide said to
> replace the corresponding tip 122 transistors in the driver board,
> which was done.But the lower left slingshot coil is still stuck on and
> the original problem of the upper slingshot not working is still there.
> Any suggestions on a fix for one or both of these problems would be
> appreciated. Thanks in advance
>