Re: Tech: System 11 display PS question


Just to add a bit more to this.
The displays can work with voltages as low as 150V but were never expected
to. They expect a minimum of 170 volt differential and a maximum of 200
volt differential across the display. The Williams boards were originally
designed to provide 190volts. They used a +100 supply and a -100 supply.
At the entry into the display board, they dropped the positive voltage by
another 10 volts thru the use of a zener diode - this make the differential
= 190V..

Your two 87 volt zeners would put the power to the display board at 174
volts. The display board zener would then drop it to 164 volts. This is
below the minimum voltage level - but barely. Might work... might not.

The use of two 91 vot zeners would put the power to the display at 182
volts. The display board zener would then drop it to 172 votls -- barely
above the minimum voltage level.

HOWEVER, the high voltage supply wasn't real accurate. Tolerance of the
supply could be off by as much as plus or minus 5%... possible more
depending on voltage drops thru sloppy connectors, etc. These tolerances
can take the supply out of that 170V to 200V window.

For the sake of the precious display driver IC's - lower voltage = good (so
would lower current but can't do nothing about that). Lower voltage to the
display it self may be good.... and might not be as well. Depends on
condition of your display.

And, another thing to remember -- the lower you have your voltage -- the
more voltage the MJE15030/MJE15031 transistors have to drop. They perform
this voltage drop by dissipating it as power.... AKA heat. But remember
these transistors are far cheaper than the 6118 and 7180 display drivers.

-- Ed



"Fred Kemper" <pbgarage@xxxxxxxxxx> wrote in message
news:de376c018or@xxxxxxxxxxxxxxxxxxxxx
> WMS switched to the 91volt in later revisions. They
> also swapped values on zeners on the later WPC
> games, and didn't always publish that info, either. All
> of this in an attempt to prolong service life of the
> displays.
>
> The Marvin site is only presenting info that has
> been discovered elsewhere. Nothing new.
>
> A gas plasma display as used in pinball, can "light"
> at as low as ~150vdc (Would be nice.), but most
> will require more. A new display tube _should_ be
> 'burned in' for several hours at ~190vdc to obtain
> the maximum expected service life.
>
> An "aged" display may require a little more juice
> to see all of the segments. 200vdc will do that!
>
> --
> Fred
> TX
> CARGPB#8
> ******************
>
>
>
> <redwing196@xxxxxxx> wrote in message
> news:1124402803.354424.54280@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> I must be missing something here. Why does Marvin's site recommend
>> switching to 91 volt zeners to lengthen the life of the displays? And
>> why would 87 volt zeners be that much of a difference?
>>
>> Jim
>>
>
>


.

Relevant Pages

  • Capacitor question
    ... Simply put can a 35 volt 470 uf capacitor be used in place of a 25 ... My BF display is resetting.I am getting the cpu boot screen. ... Display Driver Voltage is up to 4.95 but still resetting. ...
    (rec.games.pinball)
  • Re: haunted house NO DISPLAYS help!!
    ... Are you checking the transformer voltage with a digital or analog volt ... Even though your displays were tested as good, try firing up the game ... displays including the status display and the bonus count display). ...
    (rec.games.pinball)
  • Re: DX7 dead
    ... Gareth Magennis wrote: ... display just stays blank, and nothing will operate. ... Are all / most of the DX7 boards supplied with 5 volt DC power? ... voltage DC end), I guess. ...
    (rec.music.makers.synth)
  • Re: DX7 dead
    ... Gareth Magennis wrote: ... display just stays blank, and nothing will operate. ... Are all / most of the DX7 boards supplied with 5 volt DC power? ... voltage DC end), I guess. ...
    (rec.music.makers.synth)
  • Re: Tech: System 11 display over voltage?
    ... The problem is that I'm changing some of the 6118's on the display ... to change the zeners on the power driver board anyway to get the ... voltage down don't I? ...
    (rec.games.pinball)