Help! Dedicated switch problem.

[bill]

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

I have a Judge Dredd with no response to any of the dedicated switches
- eg, coin switches, self test/volume control buttons. Replaced U 15,
16, and 17 - the two 3439s and the 74ls240. No improvement. Checked
continuity from the edge cnnectors to the chips and all looks good. I
know its the board and not a power supply issue or switch wiring
problem because I swapped with a STNG board and this works fine in the
JD. What else am I overlooking that would take out all 8 of these
switches? Thanks for any suggestions.

 

[bill]

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

Sorry - I meant to type 339s, not 3439s.

 

[Guest]

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

Bill,

You might want to re-check for an intermittent black wire on the coin
door.

--
PinTed


Bill wrote:
> I have a Judge Dredd with no response to any of the dedicated switches
> - eg, coin switches, self test/volume control buttons. Replaced U 15,
> 16, and 17 - the two 3439s and the 74ls240. No improvement. Checked
> continuity from the edge cnnectors to the chips and all looks good. I
> know its the board and not a power supply issue or switch wiring
> problem because I swapped with a STNG board and this works fine in the
> JD. What else am I overlooking that would take out all 8 of these
> switches? Thanks for any suggestions.

 

[Guest]

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

Broken wire, back of switches shorted to metal, screw or something stuck
behind coin door interface board, short in the door harness. That is what
I'd be thinking. LTG

"Bill" <sbmania@msn.com> wrote in message
news:1126104097.849493.308910@g14g2000cwa.googlegroups.com...
> I have a Judge Dredd with no response to any of the dedicated switches
> - eg, coin switches, self test/volume control buttons. Replaced U 15,
> 16, and 17 - the two 3439s and the 74ls240. No improvement. Checked
> continuity from the edge cnnectors to the chips and all looks good. I
> know its the board and not a power supply issue or switch wiring
> problem because I swapped with a STNG board and this works fine in the
> JD. What else am I overlooking that would take out all 8 of these
> switches? Thanks for any suggestions.
>

 

[Guest]

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

Lloyd Olson wrote:
> something stuck behind coin door interface board

Thanks Lloyd

Andrew

 

[Guest]

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

Check for a good ground. One side of dedicated switches (orange wire) comes
from MPU board and through switch. After the switch, it is grounded. If
you have no ground (wires, braid cut), then they won't work. Some arcades
would clip the wire(s) to prevent attendants from giving free games (service
credits)- we've had to fix a lot of these that have come through our shop.

You can also remove the connector at bottom of MPU board and ground the
corresponding pins to see if it works that way. If so, then you've got a
wiring problem- not MPU board problem.

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!



"Bill" <sbmania@msn.com> wrote in message
news:1126104097.849493.308910@g14g2000cwa.googlegroups.com...
> I have a Judge Dredd with no response to any of the dedicated switches
> - eg, coin switches, self test/volume control buttons. Replaced U 15,
> 16, and 17 - the two 3439s and the 74ls240. No improvement. Checked
> continuity from the edge cnnectors to the chips and all looks good. I
> know its the board and not a power supply issue or switch wiring
> problem because I swapped with a STNG board and this works fine in the
> JD. What else am I overlooking that would take out all 8 of these
> switches? Thanks for any suggestions.
>

 

[bill]

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

Thanks for info. Its definitely on board as grounding the pins does
not work and I have continuity from coin door all the way to board.
Also, a substituted STNG board fixed the problem. But having replaced
U15, 16 & 17, I don't see what other chips would cause the problem.
There was battery leakage on the board but I'm not finding any bad
traces so far. The problem would have to be common to all 8 dedicated
switches. Thanks!

 

[Guest]

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

It's not an IC if you've replaced them already. With battery corrosion,
no doubt you have an open trace on the board and as you've already said
it will be something common to all your dedicated switches. So start
checking voltages in places common to all the switches. Do you have
good 5v on pins 4,6,8,10 of LM339s U16 and U17? Over 5v on pins
5,7,9,11 dropping below 5v as you ground connections at J205 or
activate the various switches? 12v power at pin 3? Ground at pin 12? 5v
feeding all resistors R35-R41? Good connection from pins 1 and 19 of
U15 to U9 asic pin 50? Good 5v at pin 20 of U15? Good ground at pin 10
of U15? Check these out. If any are not what they should be,
investigate to find the open point between there and the working part
of the board.
Bill wrote:
> Thanks for info. Its definitely on board as grounding the pins does
> not work and I have continuity from coin door all the way to board.
> Also, a substituted STNG board fixed the problem. But having replaced
> U15, 16 & 17, I don't see what other chips would cause the problem.
> There was battery leakage on the board but I'm not finding any bad
> traces so far. The problem would have to be common to all 8 dedicated
> switches. Thanks!

 

[bill]

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

Ron-
Thank you kindly for your detailed check list of possible problem
areas. Using your reply, I quickly found that the 12v feed to pin 3 of
the 339s was missing. Although I couldn't find an open (it must be a
top trace hidden under the new chip socket) I just jumpered 12v from
the nearby u20 to pin 3 and all is now correct! Thank you for taking
the time to assist, and all others who offered suggestions as well!
This group is really helpful for people in need of assistance on
technical and other subjects. Thanks!