Asteroids Deluxe brick Unreg 10.3 VDC low.

Zennmaster

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Hi All -

It's a weird and unimportant story, but my AD cabaret brick seems to have taken a hit. Before I did anything, the 10.3 (10.6) VDC unregulated pins at J5 were giving me 2.3 VDC. I installed the bridge rectifier from a Bob Roberts rebuild kit, and now I'm getting 8.5 VDC on those pins.

Could this have just been a bad BR, and I should try again, or is there something else I should be looking at?

Also, the same event that smoked my brick also seems to have hit my AR, so that's going to be the next item on the list, but it's currently unavailable for any further testing.

Thanks!

-Michael
 
Is the 8.3V with the AR attached, or with no load?

If it's with the AR attached, check with no load, and suspect the AR. Pull and test the 2N3055 and TIP32. If those check ok with a DMM, replace the LM305 (and maybe the 3055 anyway, as I've seen a couple that were ok on the DMM, but crapped out under load).

Also, don't use 3055's from Bob Roberts. He was selling bad counterfeits in his kits for a while, which a lot of people got burned from.
 
Is the 8.3V with the AR attached, or with no load?

If it's with the AR attached, check with no load, and suspect the AR. Pull and test the 2N3055 and TIP32. If those check ok with a DMM, replace the LM305 (and maybe the 3055 anyway, as I've seen a couple that were ok on the DMM, but crapped out under load).

Also, don't use 3055's from Bob Roberts. He was selling bad counterfeits in his kits for a while, which a lot of people got burned from.

Great to hear from you on this!

The 8.5 is without load, directly from the J5 connector.

The AR is going to be another can of worms, I'm sure, but I've got a box of 3055's waiting. :)
 
Next (and sort of the only big thing left), is to replace the big blue. I don't have any experience with these failing, but it's in the realm of possibility, if it's not a bad BR.

Also, check to make sure none of the slide on connectors on the fuse block have any signs of heat damage (burning, melting). They can corrode and go bad, in which case you can just snip them off, clean the fuse block connector, and crimp a new one on.

Also, make sure your meter is ok. We just went through this same thing in another thread, and it was the guy's meter. Sanity check it on a 9VDC battery, 12VDC car battery, and your 120VAC wall outlet.

Worst case it's the transformer, but I'd say that's the least likely.
 
Next (and sort of the only big thing left), is to replace the big blue. I don't have any experience with these failing, but it's in the realm of possibility, if it's not a bad BR.

Also, check to make sure none of the slide on connectors on the fuse block have any signs of heat damage (burning, melting). They can corrode and go bad, in which case you can just snip them off, clean the fuse block connector, and crimp a new one on.

Also, make sure your meter is ok. We just went through this same thing in another thread, and it was the guy's meter. Sanity check it on a 9VDC battery, 12VDC car battery, and your 120VAC wall outlet.

Worst case it's the transformer, but I'd say that's the least likely.

I'd actually really like it if it turned out to be my meter! :)

I'll probably replace the entire fuse block and connectors, since it appears to be original, and doesn't look especially beautiful.

I've got a spare Big Blue around somewhere. I'll try all this and report back.

Thanks again!
 
This is a long shot but I had a short or something on my coin door. I disconnected it and the voltages off the brick were great. Forget which pin the coin door runs off of on the molex connector but just disconnect the door molex and see if that changes your results.
 
This is a long shot but I had a short or something on my coin door. I disconnected it and the voltages off the brick were great. Forget which pin the coin door runs off of on the molex connector but just disconnect the door molex and see if that changes your results.

Good idea, and I will definitely be checking that out, but the weirdness I am seeing is with absolutely everything downstream of the brick disconnected.

Thanks!
 
Update:

After double-checking my meter, and seeing that everything was working in that department, I decided to take another look at what was coming off of the J5 connector. This time, the 10.3VDC unregulated was stable at 15.4VDC. I then checked the other voltages, and found that they were within 10% of where they were supposed to be, which I interpreted to be "About right". I was then in a position where everything seemed to be moving around, which got me to suspect the only real part left, the Big Blue. I had one on the shelf, so I installed it, and now I'm getting

15.18 VDC steady on the unregulated 10.3,
5.8 VAC steady on the 6.1 VAC,
36.2 VAC steady on the 36 VAC,
65.1 VACsteady on the 60 VAC.

This seemed pretty good, so I hooked the AR back on, and got zilch from the 10.3 VDC unregulated test point, and another zero on the 5V.

So, the next step will be a rebuild on the AR, and I'll let you know what happens.
 
Ohm out +5V to GND (with power off) ... seems you have a short. Might be in the ARII or in harness or on logic board.
 
The 10.3V test point corresponds to the input voltage for the AR. It should read the same 15.18V you measured on the brick.

If it isn't, the problem is either the harness, or maybe a broken input pin on the AR connector for the 10.3v line. Power is not getting into your AR, so you don't know if the AR is bad or not.

Look for broken wires, traces, or connectors. Tone everything out with your DMM.
 
Ok, some good news, some bad news:

After messing around a bit, I found I was seeing 5.58 VDC at the 10.3 test point on the AR.

Better than zero, but not what we are after.

Continuity tested out on the harness, all four pins on the J6 connector, which is 2 10.3 VDC and 2 ground.

Everything I know about electronics tells me a voltage drop from 15-ish to 5-ish is just weird in 3 feet of wire, so I pulled J5 off of the brick again, just to make sure I was still getting 15.18.

Of course, it was 5.58. Looks like I'm back to the brick. :(

I'm really at a loss now.
 
When you check the brick, try doing it upside down, with the cover off (carefully!). Make sure you're getting the same voltage at the '+' terminal of the BR, and the positive terminal of the big blue, as you are at the output pin on J5.

Also, if you do get it back to 15V again (and maybe you're already doing this), but the next step is to check things with the AR attached, but not the game board. Just to keep things as simple as possible, and step-by step, with no extra variables. You can also leave the monitor unplugged as well. You want to make sure you have the proper voltages at the input and output of the AR with no load, before you try it with a load.
 
When you check the brick, try doing it upside down, with the cover off (carefully!). Make sure you're getting the same voltage at the '+' terminal of the BR, and the positive terminal of the big blue, as you are at the output pin on J5.

Also, if you do get it back to 15V again (and maybe you're already doing this), but the next step is to check things with the AR attached, but not the game board. Just to keep things as simple as possible, and step-by step, with no extra variables. You can also leave the monitor unplugged as well. You want to make sure you have the proper voltages at the input and output of the AR with no load, before you try it with a load.

Will definitely do. Thanks as always for your help! I'm going to set this aside for tonight though, or else I might end up with some new data on the aerodynamics of an Atari power brick. ;)
 
Another update: The brick now seems to be somewhat stable in the 14-15v region on the unregulated rail. I was able to reattach the AR (and nothing else), and got the same voltage at the 10.3 test point (Progress!).

However, I was getting about 12.7v at the +5 test point :eek:. This scared me enough that I took a reading off the harness, at the 5v connection that would have gone into the PCB. Sure enough, 12.7. :001_scry:

Looking at the schematic, and back to what I think you (andrewb) were originally saying, it's time to look at the tip32 at Q2 and the 3055 at Q3.

Now, the big question: what kind of terrible nastiness should I be looking for if the PCB took over 12v on the 5V line?

I am under the impression that this is not a case of the sense circuit doing what's supposed to.
 
It's most likely a bad 2N3055 (or LM305), not the sense circuit. You can't really test the 3055 properly without removing it, as you'll get false readings otherwise, but just remove the two nuts (do not unsolder the screws if they are soldered to the PCB), suck the solder off of the two pins, grab it with a pliers, and it will pop right off. Then test it with a DMM, like any other transistor.

Not much you can do about it except replace it and see how bad the board is.

Also, check all of the diodes on on the 5V side, to make sure none are shorted.


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