Ghosting on Bally displays

[Guest]

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

The two player displays have the most significant digit (MSD) ghosted
one digit to the left. The ghost probably is 1/3 the illumination of
the MSD. I have swapped U10/U11, disconnected 1 display at a time to
see if there was interference. I also removed the sound board
temporarily. Nothing corrects the problem. Everything else works fine
on the machine.

I have checked connectors and they appear OK also. Any thoughts?

Andy

 

[Guest]

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

You may have one display assembly actually
causing the problem.

Try swapping them around to narrow the search.

Unplugging them one at a time doesn't always
catch this.

--
Fred
TX
CARGPB#8
******************






<paflys@yahoo.com> wrote in message news:1125721030.981012.94750@g49g2000cwa.googlegroups.com...
> The two player displays have the most significant digit (MSD) ghosted
> one digit to the left. The ghost probably is 1/3 the illumination of
> the MSD. I have swapped U10/U11, disconnected 1 display at a time to
> see if there was interference. I also removed the sound board
> temporarily. Nothing corrects the problem. Everything else works fine
> on the machine.
>
> I have checked connectors and they appear OK also. Any thoughts?
>
> Andy
>

 

[Guest]

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

Tried swapping the displays, still have the ghosting. Also checked
high voltage section and it is OK at 170V.

Not sure where to look next. I guess I will pull MPU and check header
pins one more time.

 

[Guest]

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

<paflys@yahoo.com> wrote:
> Tried swapping the displays, still have the ghosting. Also checked
> high voltage section and it is OK at 170V.

170vdc is at the very low end of the adjustable range for TP2 (display
output voltage- adjustable by board-mounted pot near TP2). I would try
adjusting the pot to make the voltage about 185vdc and see if it changes
anything.

You can set the voltage to 175-195vdc, which is the "safe" acceptable range
for display power. The rule of thumb is that the higher the voltage is set,
the easier it is on the components, but harder on the displays. And
vice-versa. So something right in the middle (185vdc) is usually considered
good.

Your voltage at TP4 is fixed and should be about 240vdc.

USE CAUTION when measuring/adjusting voltage here- this voltage can kill.

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!

 

[Guest]

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

Tried adjusting the HV to 185V however the ghosting still appears.
This is a Rapid Fire with 2 7 digit score displays and 1 6 digit for
the credits/bases, etc.

The 6 digit has no ghosting. Only the 2 7 digit displays. This is the
first time I powered up this machine. I did try swapping U10/U11
(6821's) but no difference. Also tried unplugging each and also tried
swapping positions. Still have ghosting.

Both displays are Bally A2518-21. Any recommendations to check
strobing?

Thanks, Andy

John Robertson wrote:
> On 2005-09-05 13:49:38 -0700, paflys@yahoo.com said:
>
> > Tried swapping the displays, still have the ghosting. Also checked
> > high voltage section and it is OK at 170V.
> >
> > Not sure where to look next. I guess I will pull MPU and check header
> > pins one more time.
>
> This might be a 6821 with small issues, try swapping the two (mark
> first) on your MPU to see if the problem goes away. If it does then get
> a new 6821 for U10 (now living in U11 I think).
>
> This is could be a strobe issue, also if you have mixed Stern and Bally
> displays that can be a result...
> Was the game working fine, then this happened, or did you work on it or
> just buy it?
>
> John :-#)#
> --
> (Please post followups or tech enquires to the newsgroup) John's
> Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call
> (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
> www.flippers.com "Old pinballers never die, they
> just flip out."

 

[Guest]

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

On 2005-09-05 13:49:38 -0700, paflys@yahoo.com said:

> Tried swapping the displays, still have the ghosting. Also checked
> high voltage section and it is OK at 170V.
>
> Not sure where to look next. I guess I will pull MPU and check header
> pins one more time.

This might be a 6821 with small issues, try swapping the two (mark
first) on your MPU to see if the problem goes away. If it does then get
a new 6821 for U10 (now living in U11 I think).

This is could be a strobe issue, also if you have mixed Stern and Bally
displays that can be a result...
Was the game working fine, then this happened, or did you work on it or
just buy it?

John :-#)#
--
(Please post followups or tech enquires to the newsgroup) John's
Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com "Old pinballers never die, they
just flip out."

 

[Guest]

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

Dumb question. Did this game originally use 6 or 7 digit displays? I do
not remember. If 6's then that would explain the ghosting...

Check for continuity for the strobe lines from the displays to the
control logic - or at least to the buffer components on the
motherboard. Perhaps a pin is not making proper connection in the brown
Molex plug on the upper left of the MPU...

John :-#)#

On 2005-09-06 20:01:26 -0700, paflys@yahoo.com said:

> Tried adjusting the HV to 185V however the ghosting still appears.
> This is a Rapid Fire with 2 7 digit score displays and 1 6 digit for
> the credits/bases, etc.
>
> The 6 digit has no ghosting. Only the 2 7 digit displays. This is the
> first time I powered up this machine. I did try swapping U10/U11
> (6821's) but no difference. Also tried unplugging each and also tried
> swapping positions. Still have ghosting.
>
> Both displays are Bally A2518-21. Any recommendations to check
> strobing?
>
> Thanks, Andy
>
> John Robertson wrote:
>> On 2005-09-05 13:49:38 -0700, paflys@yahoo.com said:
>>
>>> Tried swapping the displays, still have the ghosting. Also checked
>>> high voltage section and it is OK at 170V.
>>>
>>> Not sure where to look next. I guess I will pull MPU and check header
>>> pins one more time.
>>
>> This might be a 6821 with small issues, try swapping the two (mark
>> first) on your MPU to see if the problem goes away. If it does then get
>> a new 6821 for U10 (now living in U11 I think).
>>
>> This is could be a strobe issue, also if you have mixed Stern and Bally
>> displays that can be a result...
>> Was the game working fine, then this happened, or did you work on it or
>> just buy it?
>>
>> John :-#)#
>> --
>> (Please post followups or tech enquires to the newsgroup) John's
>> Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call
>> (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
>> www.flippers.com "Old pinballers never die, they
>> just flip out."


--
(Please post followups or tech enquires to the newsgroup) John's
Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com "Old pinballers never die, they
just flip out."

 

[Guest]

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

Yes, I experienced this on a BLY Skateball. It
had 6 digit displays installed instead of the required
7 digit. (First BLY to have them, too.)

Indeed a head scratcher!

Fred
TX
CARGPB#8
==================================

John Robertson wrote:
> Dumb question. Did this game originally use 6 or 7 digit displays? I do
> not remember. If 6's then that would explain the ghosting...
>
> Check for continuity for the strobe lines from the displays to the
> control logic - or at least to the buffer components on the
> motherboard. Perhaps a pin is not making proper connection in the brown
> Molex plug on the upper left of the MPU...
>
> John :-#)#

 

[Guest]

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

BINGO!!!! I know the machine was suppose to have 7 digit displays but
assumed that the correct ones were installed. I just looked tonight
and I have 6 digit displays in all three locations.

Question now is where to locate affordable 7 digit displays, afterall
we are talking about a RapidFire!!

Sugegstions would be appreciated. Thanks again to all who replied.
Andy

Fred Kemper wrote:
> Yes, I experienced this on a BLY Skateball. It
> had 6 digit displays installed instead of the required
> 7 digit. (First BLY to have them, too.)
>
> Indeed a head scratcher!
>
> Fred
> TX
> CARGPB#8
> ==================================
>
> John Robertson wrote:
> > Dumb question. Did this game originally use 6 or 7 digit displays? I do
> > not remember. If 6's then that would explain the ghosting...
> >
> > Check for continuity for the strobe lines from the displays to the
> > control logic - or at least to the buffer components on the
> > motherboard. Perhaps a pin is not making proper connection in the brown
> > Molex plug on the upper left of the MPU...
> >
> > John :-#)#

 

[Guest]

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

Mayfair sells tested working ones not too expensively.

I got a set from ebay that were 7 digit glass in 6 digit circuit
boards. Needless to say, they don't work very well. I can either do
extensive rewiring on the board or try to get 7 digit boards with bad
glass and move the glass over.

I'm thinking that a custom part that changes the signals to enable use
of a 6 digit in a 7 digit machine (would sit on the upper left
connector from the CPU) and shifts the digits over one... hmmm..... I
have a lot of extra 6 digit displays but not many 7's (if any!) That's
what I get for buying so many projects with missing displays!