Space Duel 5V halves

Zinfer

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I have a good solid +5v from the ARII board. However when I plug in the header to the Space Duel PCB it instantly drops that to 2.65v. That is a killer. Bumping the ARII power isn't gonna help that. Coin lamps, PCB, Game Select, Spot Killer LED's lit. No coin up, no monitor activity.
The boards' never had an initial repair since i've owned it as purchased 'untested' a few years ago. I'll recheck for overly hot ic's.
 
Okey doke. Thanks. I saw there were some upgrades on that chip. Nice to see.
 
Do you have another Audio/Regulator II board you could toss in it? A bad 2N3055 can cause that issue.

Edward
 
I'll need to run to the storage unit. I think I have another but it wasn't rated for this cabinet. It was an ARII but an older release version. I guess that counts as a yes and no. An NPN transistor? mm. I've tested the ARII for a solid 5v outbound. As well as the 10 and I believe another -5v. Wouldn't a bad transistor from the audio regulator affect the taps of the audio regulator as far as voltage measurements?? I only lost the 5v after plugging into the Main PCB as I measured from the main pcb. Hrm. Come to think of it, I never measured back at the ARII after finding the 2.65 on the main pcb when I plugged in.


Do you have another Audio/Regulator II board you could toss in it? A bad 2N3055 can cause that issue.

Edward
 
Couple of possibilities:

You could have some really bad connectors and you're getting a two and a half volt drop by the time it gets to the board.

You have a faulty regulator that's failing under load.

The game board is shorted and drawing the voltage way down. Check the resistance between the +5v and Ground buses on the game board (without it being plugged into the harness). See what you get.

-Ian
 
I've ordered the 2n3055 to check out that issue. Also going after an AVG replacement. I measured CR1 and it's dropping to 2.70 before it ever leaves the ARII to get to the Main PCB.
.909 between GRD and +5v powered off, harness disconnected.

Couple of possibilities:

You could have some really bad connectors and you're getting a two and a half volt drop by the time it gets to the board.

You have a faulty regulator that's failing under load.

The game board is shorted and drawing the voltage way down. Check the resistance between the +5v and Ground buses on the game board (without it being plugged into the harness). See what you get.

-Ian
 
.909 between GRD and +5v powered off, harness disconnected.

.909 ohms?!?! You have a short. No way should the resistance be that low.

Time for some bench troubleshooting with a meter. Pull socketed chips and keep re-checking the resistance between +5 and ground. It's very possible something besides a chip is shorted too. Look for tantalum caps - those tend to fail shorted when they go.

-Ian
 
Alright. I'll take that on tonight and post what I find. Thanks for the tip.

.909 ohms?!?! You have a short. No way should the resistance be that low.

Time for some bench troubleshooting with a meter. Pull socketed chips and keep re-checking the resistance between +5 and ground. It's very possible something besides a chip is shorted too. Look for tantalum caps - those tend to fail shorted when they go.

-Ian
 
Placed an order for a couple of them. Should have it here this week. The big blue that's in there looks brand new but I'll go ahead and replace it to see if that fixes it. Thanks for the info.

I had the same problem with my Tempest. As soon as you connected the board the +5v would drop in half. The Big Blue was bad.
 
Okay, parts finally came in today. Replaced Big Blue - no change. Replaced 2n3055 transistor on ARII-No change. The replacement AVG arrived with bent pins and one broken. There was no foam around the feet to prevent this and it was packaged in a simple anti-static bag. So my attempt to replace the AVG was subverted. I called the retailer and they informed me that they would solder a new pin on the AVG at minimal charge if I sent it back in.
It'd been nice to rule out the avg.

.909 ohms?!?! You have a short. No way should the resistance be that low.

Time for some bench troubleshooting with a meter. Pull socketed chips and keep re-checking the resistance between +5 and ground. It's very possible something besides a chip is shorted too. Look for tantalum caps - those tend to fail shorted when they go.

-Ian
 
If I just pulled the avg to test for the +5 voltage drop would that have any negative affects on the rest of the pcb?
 
You don't have to swap parts, or plug the game board into the harness. You have already established that the resistance between the +5v and Ground is less than 1 ohm. That's almost a direct short. The fact that you're not blowing fuses is amazing in itself. Check the resistance between +5 and Ground, and then start removing parts, one at a time. Honestly, I don't think it's a chip. It's probably a capacitor, or some part that got bent.

-Ian
 
You don't have to swap parts, or plug the game board into the harness. You have already established that the resistance between the +5v and Ground is less than 1 ohm. That's almost a direct short. The fact that you're not blowing fuses is amazing in itself.

Yeah, I agree......and the fact that he's getting 2-2.5VDC....doesn't seem possible (with a dead short).

Edward
 
Yeah, I agree......and the fact that he's getting 2-2.5VDC....doesn't seem possible (with a dead short).

Edward

Yeah, I know. The only thing I can figure is that whatever is shorted is increasing in resistance when it gets hot. Either that, or the extra few ohms of resistance in the wiring and the edge connector (which is probably a bit crispy by now) is contributing...

But still. With that kind of short there should be some component on the board getting *really* hot.

-Ian
 
A heat check would be the simplest. I'll pull the board out and onto the bench again.
 
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