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TECH : Q*Bert Power Supply Problems

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Anonymous
a b ) Power supply
July 31, 2005 6:11:43 PM

Archived from groups: rec.games.video.arcade.collecting (More info?)

I have a Q*Bert with the original power supply and a switching power
supply that was working when I got it.

One time I plugged it in, heard the knocker, and nothing. Now when its
plugged in it gets nothing.

I have been checking voltages all over the place, and am getting the
expected AC voltages on the safety switches and the cable assembly going
into the bottom panel assembly (power brick).

No voltage is getting to the monitor or the switching power supply.

I am getting voltage on the service outlet on the bottom panel assembly.

Since I have a switching power supply and no power getting to it, the
various boards are not getting any of the power that would be coming
from that power supply. I have tested that power supply outside of the
q*bert game and it is working.

I have replaced all of the fuses on the power brick except the 2 amp and
the 4 amp which I will try later today. This had no effect and none
of them seemed burned out anyway, however I did notice that the fuse at
location F4 which should have been a 10 amp fuse was actually a 30 amp
fuse (big thanks to whomever did that!) I've replaced it with the 10
amp fuse, clearly one "power-on" too late.

I had posted this problem before and got suggestions about the
power-supply board. I've done some checking of parts on there and did
find a bad transisor and zener diode, and replaced those parts. However
no power is getting there at all still, so I think there is a problem
prior to that which must be addressed. Maybe something wrong with the
power brick in the bottom of the machine...


Any ideas on where (on the machine only, please!) I should stick my
multimeter probes looking for problems, and what I should be looking
for? What's involved in testing one of these outside of a machine and
rebuilding it? Any techs in the phoenix area who might be able to look
at this (paid of course)?


Thanks for any help,

Shawn
Anonymous
a b ) Power supply
July 31, 2005 7:00:24 PM

Archived from groups: rec.games.video.arcade.collecting (More info?)

One problem I have found on several Qberts, is that the power supply
will go and cause one of the fuses in the bottom to go (forgot which
one) Which will also make the monitor dead. I would check all the fues
at the bottom with a meter to be sure they are good, even if they look
ok. If they are good, check to be sure you have power to the power
supply board. If you want to send me your PS, I can repair it (im in
Chicago). I have a dedicated Qbert to test it in also.

Troy
Anonymous
a b ) Power supply
July 31, 2005 10:21:09 PM

Archived from groups: rec.games.video.arcade.collecting (More info?)

I would check every fuse there, even on the original power supply with
a DMM. Don't trust just looking at them. Especially that 10 Amp F4.

Try lightly pushing on the filter board and see if that does anything
while you have the game turned on.

Plug something into the outlet on the bottom panel assembly and see if
you can power something, like a light.

Make sure that the interlock switches are set so that the game will
come on, like Matt said.

Those wiring harness connectors that Gottlieb used have a habit of
going bad also, when you least expect it. And they seem to use a lot
of them.

My thoughts anyway, good luck!!
-Tim
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Anonymous
a b ) Power supply
August 1, 2005 1:57:35 AM

Archived from groups: rec.games.video.arcade.collecting (More info?)

Thanks for the suggestions, I'll be checking them out Friday night when
I am back in town.

Just as a follow up, I tested all of the fuses with a multimeter and
they seemed fine, but I tried replacing them all anyway...no luck...

Also both of the interlock switches were pulled out, I even took the
covers off of them and tested voltage there... seemed correct...

I'll check out the other stuff in a few days and let you know how it
goes, thanks again!



Shawn Pauling wrote:
>
> I have a Q*Bert with the original power supply and a switching power
> supply that was working when I got it.
>
> One time I plugged it in, heard the knocker, and nothing. Now when its
> plugged in it gets nothing.
>
> I have been checking voltages all over the place, and am getting the
> expected AC voltages on the safety switches and the cable assembly going
> into the bottom panel assembly (power brick).
>
> No voltage is getting to the monitor or the switching power supply.
>
> I am getting voltage on the service outlet on the bottom panel assembly.
>
> Since I have a switching power supply and no power getting to it, the
> various boards are not getting any of the power that would be coming
> from that power supply. I have tested that power supply outside of the
> q*bert game and it is working.
>
> I have replaced all of the fuses on the power brick except the 2 amp and
> the 4 amp which I will try later today. This had no effect and none of
> them seemed burned out anyway, however I did notice that the fuse at
> location F4 which should have been a 10 amp fuse was actually a 30 amp
> fuse (big thanks to whomever did that!) I've replaced it with the 10
> amp fuse, clearly one "power-on" too late.
>
> I had posted this problem before and got suggestions about the
> power-supply board. I've done some checking of parts on there and did
> find a bad transisor and zener diode, and replaced those parts. However
> no power is getting there at all still, so I think there is a problem
> prior to that which must be addressed. Maybe something wrong with the
> power brick in the bottom of the machine...
>
>
> Any ideas on where (on the machine only, please!) I should stick my
> multimeter probes looking for problems, and what I should be looking
> for? What's involved in testing one of these outside of a machine and
> rebuilding it? Any techs in the phoenix area who might be able to look
> at this (paid of course)?
>
>
> Thanks for any help,
>
> Shawn
Anonymous
a b ) Power supply
August 1, 2005 2:56:11 AM

Archived from groups: rec.games.video.arcade.collecting (More info?)

If all the 120 VAC wiring is original, let's assume that we've got a problem
with one of the interlock switches. There are two of them, one on the back
door, and another inside the coin door. Pull both of these all the way out.
(You may try exercising these switches, too, pulling them in and out about a
dozen times to break loose any oxidation on internal switch contacts.)

Now make sure that the main power switch is on, too.

According to the schematic, the 120 VAC service outlet is connected directly
to the incoming power line, with no switches to get in the way. That's why
you're getting voltage on it.

The monitor gets its 120 VAC through an isolation winding on the main
transformer in the bottom of the cabinet, and the marquee lamp gets its
power from that same tap. That's why neither the monitor nor the marquee is
lighting up.

There might also be some intermittent connection on connector A12 (J2/P2).
Try pulling that off and plugging it back in, looking for any dirty contacts
or bad solder joints.

F1 is the main fuse to worry about. It's supposed to be a 4-amp, slow-blow
fuse. It is in series between the line filter and the main power switch.
If it's open, the main transformer won't get any power. If it's okay, see
if you're getting 110 VAC at the input of the transformer itself -- "115V"
and "COMMON".

Another way to isolate the trouble is to pull out the power plug, and
connect your ohmmeter across the two main terminals. If both interlock
switches and the main power switch are on and okay, you should read only
about 20 ohms or so (give or take) on the meter. If the meter reads
infinity, check all the switches and fuse F1.
!