(Topic ID: 162536)

DE Star Wars - Power Supply, No 5V at CPU?


By Kordova

2 years ago



Topic Stats

  • 15 posts
  • 8 Pinsiders participating
  • Latest reply 2 years ago by ChrisHibler
  • Topic is favorited by 2 Pinsiders

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#1 2 years ago

Hello all, I'm having trouble with my DESW. It was working fine until Saturday. Trying to keep this brief, but want to be thorough.

Was working fine. Lifted the playfield to replace a bulb. Replaced bulb and lowered the playfield. No lighty-lighty when I turn on. Lifted the playfield (power still on), and the game went silent as I did so. Still had GI. Replaced bulb (bad LED) and the light powered on. Lowered the playfield and game fire back up. This was concerning to me as I assumed there was a short in the main harness running into backbox. It almost seem like the harness got squeezed between the playfield and cabinet when I raised the playfield, I had never noticed this before.

I started the game, shooter lane kicker not working (the coil which kicked the ball into the shooter lane, not the autolaunch itself). Game did a ball search and said 0 balls missing. Lifted playfield to see if I had somehow knocked the coil solders off or something. Game went silent again. Hasn't come back on since.

I've got all GI but no power to CPU or DMD. Speakers humming, so sound board getting some power. CPU test LEDs are blank. They flashed briefly yesterday on start up though, very quickly in succession, maybe half a second, and then off.

I checked all fuses and got continuity. I did find one bad fuse clip on the power supply board but it tested and seems like it's still got good contact. I'm getting +12 and -12 at the at the test points on the power supply board but only getting .7 on the 5v test point. Getting the same .7v at the 5v on the motherboard testpoint.

I'm not very good with this type of fix. Bad switch, bad coil, a quick solder here and there, I can do it. But this is above my pay grade.

At this point I am assuming bad power supply board. Perhaps I accidental shorted something with the playfield up and knocked it out, I don't know.

Thoughts, questions? I will try to be specific in any answers, but like I said, I'm not really very good with side of things.

#2 2 years ago

If you've got no +5, that's your problem.

Look at fuse clips and connectors, but odds are you have a bad cap on your power supply or more. There's a 100 mfd cap on the power supply that can go bad, and then you get no +5.

#3 2 years ago

Right away my first thought was that lifting the playfield put tension on the wiring harness, which maybe cause a short somewhere. Like johnwartjr said, you'll have to investigate getting the +5VDC back first. I would suggest that you also try to carefully try lifting the playfield with the backbox innards visible so you can see what might be pulling on what. It really seems like something happened during what you did, rather than coincidence.

#4 2 years ago

On the de power supplies there are 3 caps that all should all be replaced. They are right next (just below) the big heat sink and get cooked with time. Often one will leak and rot the board trace (like a battery). They are 100, 47 and 330 mfd caps. Note the 330 can be replaced with a 470 mfd (more common of a cap).

#5 2 years ago

you can get those caps at radio shack. should be a 10 min fix.

#6 2 years ago
Quoted from wayout440:

Right away my first thought was that lifting the playfield put tension on the wiring harness, which maybe cause a short somewhere. Like johnwartjr said, you'll have to investigate getting the +5VDC back first. I would suggest that you also try to carefully try lifting the playfield with the backbox innards visible so you can see what might be pulling on what. It really seems like something happened during what you did, rather than coincidence.

Thanks for the input, Wayout. This was my concern as well. I tried what you've suggested, lifting the playfield, while trying to see what what shorted. If revealed almost no tension whatsoever on the wiring. The harness appears to securely zip tied to the cabinet, all inside plastic coping. Virtually nothing moved. I have also "futzed" extensively with the wiring the that region attempting to identify any short to no avail. Further, this doesn't seem like it should have caused a full loss of 5V at the power supply. Though I am not ruling this out, I think my first step has to be to repair/replace the power supply first.

#7 2 years ago
Quoted from Kordova:

Thanks for the input, Wayout. This was my concern as well. I tried what you've suggested, lifting the playfield, while trying to see what what shorted. If revealed almost no tension whatsoever on the wiring. The harness appears to securely zip tied to the cabinet, all inside plastic coping. Virtually nothing moved. I have also "futzed" extensively with the wiring the that region attempting to identify any short to no avail. Further, this doesn't seem like it should have caused a full loss of 5V at the power supply. Though I am not ruling this out, I think my first step has to be to repair/replace the power supply first.

Well, at least you looked...could be coincidental. Vibration alone from lifting the playfield could have jostled something. Take care of getting the power supply running, then search again as thoroughly as possible again. That's really all you can do. If something is loose or shorting it might rear its ugly head later.

#8 2 years ago

Correlation is not causation. Forget that you lifted the playfield you're distracting yourself from the issue at hand.

#9 2 years ago
Quoted from johnwartjr:

If you've got no +5, that's your problem.
Look at fuse clips and connectors, but odds are you have a bad cap on your power supply or more. There's a 100 mfd cap on the power supply that can go bad, and then you get no +5.

I agree with john and others about the 5 volts.
Replace C2 (100uf 35v radial electrolytic capacitor) on the power supply. Make sure C2 did not leak out as well and damage the trace under C2.

#10 2 years ago

Post a hi resolution pic of the power supply showing the caps mentioned. They often leak but I'd say it was an extreme coincidence that they took that single moment to go tits up.
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

#11 2 years ago
Quoted from ChrisHibler:

Post a hi resolution pic of the power supply showing the caps mentioned. They often leak but I'd say it was an extreme coincidence that they took that single moment to go tits up.
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

These may not be high resolution enough as I'm only working on my cell phone right now. I don't see any apparent leakage or pregnant cap (maybe c8). The broke use clip is the lower left on F5.

I replaced the power supply with an XPin. Fired right up. Seems to be working perfectly. DMD even looks brighter than ever.

Seems to be the worlds biggest coincidence. I can't explain it.

Also, I found the issue with the shooter lane. The ball through switch was out due to a broken wire at the terminal connector. Re-crimp, and viola.

Thanks for the input guys.

image_(resized).jpeg
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#12 2 years ago

It looks like you might have something going on there with both C2 (which severs the 5V power path) and C7.
I can't see well enough, but look at the area between C2 and the big heat sink.
And look at the lower area of C7.
Both might be leaky.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#13 2 years ago
Quoted from ChrisHibler:

It looks like you might have something going on there with both C2 (which severs the 5V power path) and C7.
I can't see well enough, but look at the area between C2 and the big heat sink.
And look at the lower area of C7.
Both might be leaky.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

Sure enough, I see it. I already replaced the board, but will repair and see what happens. I need to work on my soldering anyway.

#14 2 years ago

C2 always cooks on these boards. It is wedged between the two heat syncs.

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