Asteroids Voltage Drop

texasmame

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The AR is fine - 6.6v to 4.2v range and it's adjustable.

The 5v regulator on the PCB tests fine.

The 5v testing at the test points on the AR is fine there. When the edge connector is placed on then it's tried again, the voltage drops to about 1.3v at both the test points on the PCB and the AR.

Tried the sense mod on the AR J7 (tied pins 1 to 2 and 4 to 6) - no difference.

Ran a 5V from the test point on the AR to the test point on the PCB, same for the ground - same voltage drop to about 1.3v. Cut the lines for the 5v on the edge connector and left the direct connections - same drop.

So, doesn't seem to be the edge connector on the PCB, at least at the 5v and ground sections. They've been cleaned well and the edge connector itself and there's no evidence of burning at all. Even running 5v and ground directly test point to test point ONLY (no edge connector at all) - still get the voltage drop once the game gets turned on.

Of course can't get in to test mode, P1 and P2 buttons are dead as well.

Anyone local have another PCB for testing or any suggestions?
 
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Some suggestions that it's the voltage reg on the AR board. If the reg was shot, wouldn't you not be able to adjust the 5v with the pot?
 
This is a problem with your AR board. The game's CPU want start because the voltage is too low. I had the same problem with my Asteroids. I changed both transistors and the electrolytic cap. on the AR1. You should be able to adjust the voltage closer to 7 V with out the main PCB attached.
 
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It's not the regulator... I bet the 2N3055 is blown. That would cause the voltage to drop when a real load was put on it.


That was it, sir. Thank you!

Just for information's sake, this was a very early board. It had a part with the markings of "SJ6880 8013" in place of the 2N3055. The 2N part was a suitable replacement.
 
That was it, sir. Thank you!

Just for information's sake, this was a very early board. It had a part with the markings of "SJ6880 8013" in place of the 2N3055. The 2N part was a suitable replacement.

Excellent. Yeah, the 2N3055 is kind of like a generic power tranny. There are plenty of other NPN trannies that could do the same job here.
 
I was quite surprised to find that Radio Shack actually still has 2N3055 (and they carry very few electronics components nowadays). And they were only a couple bucks each.

Yup, that's where I got this one. :) They also had some 555 chips!
 
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