Stargate boot problem
TWitort
just beeps rapidly with LED1 on the control board (A1) flickering.
The display just flashes a random collection of pixels. The only thing
I've checked is the +5V output of the power supply board and it's
fine. The problem points to the control board, but not sure where to
go from here. Any ideas? Any other troubleshooting I can do? The
manual doesn't mention this type of failure.
Thanks for any help!
-- TRW
Captain Neo
Did anyone unplug the DMD while the game was on? Had this happen on
my SMBMW and it fried some game specific chip by doing it. REplaced
the chip and all was well again.
Eric A.
If you did what Neo said, reseated the display ribbon cable, then you
blew the UG-8 chip on the control board. This is a programmed pal chip
and Steve Young has it or if you have a programmer contact me by
e-mail for some help.
You can also try to turn down the 5v pot and then back up again to 5
volts and if it boots it is another chip on the cpu board. That chip
is a 74hc123 Dual multivibrator.
Eric A.
313-268-0541
Gott Lieb?
Also, try booting the game w/o the DMD controller board connected to
the CPU board via the ribbon cable. Disconnect the ribbon cable with
the *power off*. It will boot blind, but this will allow you to
isolate the issue, if it is not power / ground related.
Jim
TWitort
No. I haven't had to open the backbox in years. Just started to fail
like
this several months ago. Then it would boot fine for a while, then
start
failing again. Currently it fails to boot almost all the time.
-- TRW
TWitort
I adjusted the 5V pot as suggested with no change in outcome.
-- TRW
TWitort
I'll try disconnecting the DMD display today and see what that does.
Not sure how/where to check the quality of the ground. I've got the
manual
with all the schematics.
thanks,
-- TRW
Gott Lieb?
Robertson's write up - http://www.flippers.com/gottlieb_ground_cures.html#System3.
Jim
TWitort
I disconnected the display controller board (A8) from the control
board
and powered up the game. I did not get the beeping and the continuous
rapid flashing of the control board LED.
Instead, the sound board and auxiliary sound board's LEDs light up
alternately every second or so (which I believe is correct). The
LED on the display controller slowly lights up for a few seconds then
goes off for a few seconds repeatedly. The control board's LED
rapidly
flashes 5 times every second with a brief pause between bursts.
(had to shoot video of it in slow-motion mode to make certain of the
number of blinks).
Powering down, reconnecting the display controller, then powering up
gives
the same results as before: controller board LED continuously
flashing very
rapidly, DMD controller LED on solid, sound board LED on solid, aux
sound
board LED off, continuous rapid beeping, static-like garbage on DMD.
I'd say
once every 20 power-ups it successfully boots and plays properly.
Does this point to a problem with the display controller board?
Possibly the
UG-8 chip? What's my next troubleshooting step?
Thanks for all the assistance. My son will be quite pleased if I can
get
the game working again!
-- TRW
Gott Lieb?
DMD controller. When doing this, leave the CPU to driver board ribbon
cable disconnected, just in case the one from the CPU to DMD is bad.
You don't need locked on lamps, flashers, or coils.
Jim
Gott Lieb?
Jim
Eric A.
>
> - Show quoted text -
I'd say that points directly to the 74hc123 Dual multivibrator.
TWitort
I swapped the ribbon cables and got the same result. So the cables
seem to be fine. I will be checking the grounds next.
-- TRW
Gott Lieb?
"The control board's LED rapidly
flashes 5 times every second with a brief pause between bursts.
(had to shoot video of it in slow-motion mode to make certain of the
number of blinks)".
I think Eric A. mat be onto something more so than the grounds.
Although securing the grounds better will only help with future
troubleshooting. You can then rule them out for good.
Jim
TRW777
Checked the grounds and they appear solid. I checked them by
attaching
one probe to the ground screw on the power supply plate then probed
the
ground pins on the various power connectors on the boards. They were
all consistently reading around 0.7 ohms. Is this the correct process
for
testing the grounds?
If the Dual Multivibrator needs to be replaced, it appears I'd need to
pull
the controller board, unsolder the existing chip, then solder in the
replacement? Is there any way to test the existing chip (preferably
in-place)
to make sure it's faulty before I go through the process of replacing
it?
Would a faulty multivibrator occasionally allow the game to work boot
up
and work correctly?
Thanks!
YenningComity
to go bad so even if you adjust it and nothing changes it still
doesn't rule it out.
The other is the Dual Multivibrator chip. Either one of those could be
causing the problem. If i were you I would order a new pot, chip, and
socket. Start with the pot and see if it fixes anything. If not then
move on to the multivib chip.
Pity clays guides are gone there was a very nice explanation of why
this happens. As for testing it in place I do not think there is a
way.
Last thing I can think of is to hit the reset button on the cpu board
when you are done. I have had some weird errors (no display int he
options menu) clear up by doing a reset.
Gott Lieb?
pins with your DMM probe *may* allow for continuity where there
actually wasn't.
You can test the 74HC123 using this method -
http://pinwiki.com/wiki/index.php?title=How_to..._%28solder,_desolder,_%22stitch%22,_test_transistors,_test_ICs,_etc%29#Testing_an_integrated_circuit.
When testing this way, remove all of the connectors. The less things
connected in circuit, the more accurate test. Keep in mind that the
test is not 100% foolproof, because other components tied to U11 could
potentially skew your results, if the other components have failed.
As YC suggested, change the 5v pot. I would do this regardless of
whether you are getting decent voltage currently. The failure rate on
the factory pots is extremely high.
Jim
TRW777
> You can test the grounds that way, although, pushing on the ground
> pins with your DMM probe *may* allow for continuity where there
> actually wasn't.
>
What is the best source for the replacement parts? I've gotten
stuff from Pinball Resource in the past, but I don't see either of
these things on the website.
-- TRW
Gott Lieb?
TRW777
It looks like I found the 74hc123n chip at a few different places.
I've
gotten parts from Mouser in the past and they have it in stock. The
500 ohm pot is a bit of a different animal. There are dozens of
variations
on this at Mouser and other places. Not sure which ones will fit and
are
compatible with the one I'm replacing. Any guidance on what pot to
get to replace the factory one?
Thanks!
Gott Lieb?
anywhere. Ed has the 1/2w variants on the bottom of this page -
http://www.greatplainselectronics.com/products.asp?cat=122
Jim
TRW777
> You may have to settle for a 1/2w variation. I don't see a 1w
>
> Jim
>
> On Jun 21, 3:37 am, TRW777 <t...@witort.com> wrote:
>
>
>
>
>
>
>
> > It looks like I found the 74hc123n chip at a few different places.
> > I've
> > gotten parts from Mouser in the past and they have it in stock. The
> > 500 ohm pot is a bit of a different animal. There are dozens of
> > variations
> > on this at Mouser and other places. Not sure which ones will fit and
> > are
> > compatible with the one I'm replacing. Any guidance on what pot to
> > get to replace the factory one?
>
> > Thanks!
Ordered the multivibrator and a socket for it. We'll see if that
solves the
problem. I'll get the replacement 500ohm pot later.
On a side note, I discovered that if you take the tip and ink tube out
of a Bic ball point pen (the old-fashioned Cristal version), the
narrow
end of the empty pen barrel make the perfect tool for compressing
the circuit board standoffs to remove boards from inside the backbox.
-- TRW
TRW777
Installed the new multivibrator chip and the behavior on power-up is
exactly the same. Measured the voltage at various board connectors
and I get consistent 5.0 V everywhere +/- about 0.1 V.
Any ideas on what I can try/test now? Will replacing the 500ohm pot
be of any benefit in this case when it seems to be putting out the
correct 5v output?
Thanks for any additional guidance.
rawleyd
>
> - Show quoted text -
system 3 guides halfway down the page.. keep it hush hush ;)
http://www.thepirates.net.au/arcade/index.php?directory=Pinball/PinRepair/Apr-11/Pinrepair/Pinrepair.com%20Repair%20Manuals%20Apr%202011/
TRW777
I've downloaded the PDF and am reading through it. If anyone has any
ideas
of where to focus, that would be great. I think I'll focus on the
ground remedies
found in that PDF, then the 500 ohm pot, then the U8 GAL chip.
Hopefully
it will start working with these fixes done.
- TRW