Pole Position Issue surprise surprise surprise!!

andykmv

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Location
Kilmore, Vic, Australia
(oh no not another one!)
Boardset:
namco PPII set, in a namco cab

Possible Dependencies:
Original power supply used only for monitor ISO (original PS PCB missing)
Switch Mode supply used (PChou 5v15A switcher, or 5v24A ATX PSU)
Voltage measured at board connector slightly under 4.7v (yeah i know it is too low so i have to look at an alternate PSU setup to deliver correct voltage at board power connectors)

Issue Scenario:
game boots up ok. and is rock solid.
get track select display, stable for a few seconds, starts rolling vertically.
select track ok (just hard whilst rolling)
game starts, and is rock solid.

The Question:
Other than the obvious power supply issue, has anyone seen this type of symptom and have some suggestions as to what else to look at for a reason for the display rolling ONLY during track selection ?

thanks!
 
Namco PPII

Anyone out there with a NAmco pole position that can take some pictures of the power supply PCBs and power supply brick ?

or are they the same PCB as the atari pole position power supply pcbs ?
 
Anyone out there with a NAmco pole position that can take some pictures of the power supply PCBs and power supply brick ?

or are they the same PCB as the atari pole position power supply pcbs ?


I use to have a Namco PP2 boardset.

The big difference is that the Audio section is on the main PCB
and NOT on ARII boards.

So you can actually replace the entire power brick with a good switcher
and only need to provide +5V. +12 V, and GRND to go to the main PCB.
(... but get PS with enough Amps because PP is a pig .
You can probably use a good PC Power supply (350-450W) )


Good luck.

Steph
 
The Question:
Other than the obvious power supply issue, has anyone seen this type of symptom and have some suggestions as to what else to look at for a reason for the display rolling ONLY during track selection ?

Sure! It's the monitor.

If the B+ supply is weak, then when the game goes to a uniformly light colored screen (the track select screen), the beam current goes up and the B+ drops, then the sync circuit drifts and it rolls. As soon as you're back to a screen with a large dark section (the track), the B+ supply stabilizes and you're back in business.

What kind of monitor is it? Check and adjust the B+ to ensure that it's correct. You might want to just try adjusting the vhold while it's rolling, see if you can get the control nice and centered in the range. That way, even as stuff drifts it won't go out of whack.

-Ian
 
So you can actually replace the entire power brick with a good switcher and only need to provide +5V. +12 V, and GRND to go to the main PCB. (... but get PS with enough Amps because PP is a pig . You can probably use a good PC Power supply (350-450W) )
...

thanks steph! done the atx 550w thing, does not have 5v adjust so need to rethink the number of connectors to minimise voltage drops
 
Sure! It's the monitor.

If the B+ supply is weak, then when the game goes to a uniformly light colored screen (the track select screen), the beam current goes up and the B+ drops, then the sync circuit drifts and it rolls. As soon as you're back to a screen with a large dark section (the track), the B+ supply stabilizes and you're back in business.

What kind of monitor is it? Check and adjust the B+ to ensure that it's correct. You might want to just try adjusting the vhold while it's rolling, see if you can get the control nice and centered in the range. That way, even as stuff drifts it won't go out of whack.

-Ian

kinda makes sense as the track select is mostly black, whereas the the opening screens are mostly fawn and the game screens have a lot of blue/green/white/red!

the owner of the boards (not mine) tried the vsize while rolling and i watched, not sure if he tried the vhold or not.
not sure what make/model the screen is.

a few things to try out and check - many thanks!
 
whats the 5 volts at the power supply itself? If you have 5.0 or 5.1 there, direct wire your ground and +5 to the test points on the pcbs.

if you only have 4.7 volts at the power supply itself, you need a new/better one
 
whats the 5 volts at the power supply itself? If you have 5.0 or 5.1 there, direct wire your ground and +5 to the test points on the pcbs.

if you only have 4.7 volts at the power supply itself, you need a new/better one

4.7 at the connectors on the PCB, so it is still not quite enough with this particular ATX power supply i am using.

looks like i'll be setting up a pair of peter chou style switch mode power supplies to replace the old single switcher, rather than replace with ATX power supply unit, so i can crank up the 5v rail to 5.25 v at the psu, for an expected 4.9 at the game pcb.

i havent tried direct wiring to the test points as we need to keep the matenlok connections for easy board swap out during repair of three of the same boardsets, although i may just test it with some clip leads for a temporary test!

thanks for the response!
 
whats the 5 volts at the power supply itself? If you have 5.0 or 5.1 there, direct wire your ground and +5 to the test points on the pcbs.

if you only have 4.7 volts at the power supply itself, you need a new/better one

As long as you have the current to back it up (i.e. a good hefty supply), the 4.7v isn't a problem. I've got my friend's pole position running off an AT computer power supply, direct wired to test point lugs, and the voltage at the board is only like 4.75. The thing has been rock solid for months.

The key is to be sure that you don't get voltage drops from one end of the board to the other... With the original ARII supplies in the game, I was reading a voltage drop of a little over half a volt between two test points on opposite ends of the board.

A computer power supply works great for these games.

-Ian
 
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