Asteroids Deluxe brick Unreg 10.3 VDC low.

What was causing the AR to put out low voltage before? Did you find a cause, or did it just start working again?

I think the problem was with the brick. The test point was either showing zero (no continuity, as you pointed out), or it was mirroring the brick voltage (proper continuity, just the wrong value). As far as I can tell, the AR was doing what it is supposed to.

I'll pull the 3055 and report back.

As always, thank you VERY much!
 
Sorry, I misspoke and meant the brick, not the AR. The brick was putting out low voltage. That's a little concerning, to not find a cause for.
 
Sorry, I misspoke and meant the brick, not the AR. The brick was putting out low voltage. That's a little concerning, to not find a cause for.

In that case, it seems that yes, it just started working again. And I agree, it's "Non-Optimal". :)

On the other hand, I'm kind of okay if it continues to go "normal-or-less", and not "Line current everywhere".
 
Update: I've pretty much run out of things to test. I had to wait for the slow boat to bring me some LM305s, and since I haven't found a method to test these, I just went ahead and replaced it. I also pulled and tested both IN4002s. Both diodes tested fine, and when I hooked the AR back up to the brick, no change.

To summarize: I'm getting about 13.5VDC at the 10.3 unreg test point (normal), and I'm also getting the same reading at the 5VDC test point. It sure looks to me like there just isn't any voltage regulation going on.

I'll be the first to admit that I am no expert, but it really seems like I've tested or replaced just about everything in the circuit. I haven't attacked the caps or resistors yet, cold these fail in such a way that it would cause this problem?

Thanks again!
 
Dumb question, but did you pull the 3055 to test it? You will get false readings if you try to test it in-circuit. (It's also possible you're being tricked by some other component, if you measured those in-circuit as well. You'll think it's ok, but maybe it's just looking that way, because of something else in the circuit.)

If you think you've checked everything, and it's still not working, you're basically in the 'question all of your assumptions' mode of troubleshooting.

I suppose a shorted cap maybe could mess things up, but I can't say I've seen one, and you should be able to test that with your DMM pretty easily. Ideally, you should have a cap meter, and lift one leg of each cap to test it. Also, a cracked resistor could maybe do the same. I sometimes will push on each resistor (and the glass caps too, if you have them), to make sure they're solid. If they're cracked, they'll usually break apart.

Also, I don't know if I mentioned this before, but test the pins in the connectors for continuity. I've had a couple where the pins broke inside the housing, near the base, so they didn't pull out, but they weren't making contact.

If all else fails, send it in. I'll figure it out for ya, for the price of shipping.
 
Dumb question, but did you pull the 3055 to test it? You will get false readings if you try to test it in-circuit. (It's also possible you're being tricked by some other component, if you measured those in-circuit as well. You'll think it's ok, but maybe it's just looking that way, because of something else in the circuit.)

Definitely not a dumb question! I haven't been doing this kind of work very long, but I have certainly learned that whatever time and effort I think I may be saving by testing in situ I will lose again with a hefty interest charge. :)

I did indeed pull the 3055 to test, although I can't be completely certain I tested it correctly. :)

I'll poke at the glass caps and resistors and see if anything crumbles.

I'll also pull and test R25 and R26, per VectorCollector's suggestion.

One of the main points of frustration is the way this board failed. It was fine, then I swapped in someone else's PCB to test it, and everything blew up. Since it was a pretty catastrophic failure, I guess I was thinking it would leave a big smoking hole somewhere instead of this little insidious sneaky stuff.

If all else fails, send it in. I'll figure it out for ya, for the price of shipping.
I appreciate that! Right now I'm feeling like this is a personal challenge, so I'll give it a bit more before I cry "uncle". Also, I sort of feel like I need you to know that I actually do occasionally succeed at fixing something! :D:D:D
 
I appreciate the dialogue here. I was searching for threads related to brick voltage and I'm feeling better. I'm getting 15.0 VDC out of my brick and I was thinking that was too high. The AC voltages are all pretty close to spec. Based on nobody raising any eyebrows, I'm thinking the 15V output is OK.

Now I'm troubleshooting the AR. I'm getting 5V, but nothing on the 10.3. I'm measuring these right off the J7.

This is an Atari brick feeding an AR-II/01 in my Dig Dug.
 
10.3 is the input to the AR (which is the 15V from your brick), which gets regulated down to 5V by the AR. So it actually doesn't make sense that you'd have 5V but not 10.3 (which is normally 13-15V, though 15 is about the highest I'd expect).
 
Sorry, let me clarify.

Brick is putting out 15.0VDC, 36VAC, 6.56VAC, and 63.8VAC. It seems like the brick is OK.

The AR2 is putting out +5V on pins 5 and 6. However, pin 7 is showing nada. Pin 7 should be 10.3V. Methinks the AR2 is FUBAR. Testing the AR with the main board disconnected. Is the Sense circuit messing with my testing?

(The initial symptom is that the main board doesn't appear to power up.)
 
Following guide provided by Melchman:

http://melchman.net/arcade/Pr0n/tour/ARII/index.html

About 45% of the way down the page, there is a section titled J7+5 and SENSE. The pinout on that diagram shows +10.3VDC on pin 7.

But, since you asked, I double checked my schematic and it looks like pin 7 is supposed to be empty. Furthermore, I checked my wiring harness and there is no pin or wire in the connector.

My quest for 10.3 volts was unwarranted!
 
Hence why I asked. You should ping him and ask where he got his info, as I'm not aware of an AR having 10.3V on that pin. But maybe there is an early PCB rev that has it, as Atari did have many layout versions of the AR-II PCBs (in addition to the -0x numerical types, which all used the same PCBs, and just populated them differently). I would be very interested to see an AR with 10.3V on that pin.

Also, most boards (at least the Atari ones I repair) typically work up to 5.4-5.5V, however I have seen a couple that are particularly voltage sensitive. You probably just have one chip somewhere that is on its way out, or just finicky, and you need to keep the voltage tight as a result. You always want to set the voltage so you have 5.00-5.05V anyway, measured on the game PCB, using the 5V and GND test points.
 
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