Atari ARII-02 help

dogbowl

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I shotgunned a Bob Roberts cap kit on a (previously) working ARII-02 board (on a Tempest).

On initially plugging it in and turning the game on, the spot killer turned on and the R5 on the ARII board started smoking.

The test points on the board all test okay except for -5. I read -14v from that one.

Does anyone have any pointers to help me track this down? (I'm new to atari boards so please speak slowly)

Thanks
 
Hi there, can you take a picture of the front and back of that AR board so we can see the condition of everything. A few pictures would be better. The closer the better. That way we can see if anything looks suspicious. Check your board for solder splash on your board connecting traces that should not be connected.
 
The transistor right next to r5 on the heat sink should have a insulator and a plastic screw securing it to the heat sink, is that present?

A few pictures of one of my A/RII-02 boards

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If R5 is smoking then you probably have a bad TIP32 @ Q2. I'd be surprised if the +5V was holding.

Make sure that you installed C31 and C24 correctly and they're not reversed. The 7905 @ Q9 should have an insulator between it and the heatsink, and should be using a nylon screw. It could be fried now.

I do work on these if you find you need help.
 
I shotgunned a Bob Roberts cap kit on a (previously) working ARII-02 board (on a Tempest).

On initially plugging it in and turning the game on, the spot killer turned on and the R5 on the ARII board started smoking.

The test points on the board all test okay except for -5. I read -14v from that one.

Does anyone have any pointers to help me track this down? (I'm new to atari boards so please speak slowly)

Thanks

Did you have the game connected, or not? The -5 tends to read wrong if you don't have any load on it (Bob Robert's talks about this somewhere on his website).

More importantly, the +5 needs the +5 return from the game board because it uses that to adjust the +5 and keep it stable (so, as the game draws more current and the +5 drops a little, The ARII board makes up for it by upping the voltage and keeping it stable at +5). The problem is that if you fire up the board without the game connected, it sees 0 on those return lines and keeps upping the voltage, eventually (mere seconds later) doing damage.

You can modify the board by shorting the +5 to the +5 return on the back of the connector, but then you have to make sure the +5 looks good by yourself, and the -5 still won't operate correctly without a load. I've done this on my Missile Command because I know my game board connectors are not good, but it's a tradeoff that you have to decide on yourself.

If you search around on the forums here you should find other posts (including some by me) on the same topic.
 
Q2 and Q9 both have insulators and plastic screws. (My 7812 at Q8 doesn't have a metal screw - for what thats worth)

I did test the voltages with the PCB connected (and unfortunately the red LED on the PCB is not lighting up). Takes about 30 seconds for the R5 to start smoking so I don't like to leave it on too long.

I see that -22V comes in and goes through C31 - Q9 - C24 to get turned into -5V. What steps should I take to test out the capacitors and transistors involved?

I've attached some closeups. To my eye, all the soldering looks good...
 

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We got this figured out.

The 2N3055 at Q3 was reversed. We flipped that back around and replaced the burnt R5 and everything came back to normal.

Thanks..
 
We got this figured out.

The 2N3055 at Q3 was reversed. We flipped that back around and replaced the burnt R5 and everything came back to normal.

Thanks..

How on Earth did you do that??? The TO-3 package is supposed to fit only one way. Unless you didn't bother to re-install the mounting screws.
 
We got this figured out.

The 2N3055 at Q3 was reversed. We flipped that back around and replaced the burnt R5 and everything came back to normal.

Thanks..

OK, you're gonna have to explain THAT one - how did you get it in backwards? That's a TO-3 metal can, and the two leads are NOT on the can center. To get that in backwards, you'd have to leave off the mounting screws, OR you'd have to bend the pins over and down in a really funny way.

Oh. You left off the screws, didn't you? Thinking you'd put them back on when you were done...am I right? You do need the screws - the can is one of the transistor leads (transistors have 3 leads - on this package, 2 are pins, the can itself is the third). Without the screws holding everything in place, I don't know if it will make sufficient contact.

I think when I last swapped one of these, I cleaned out the holes, bolted the new transistor down, then soldered it.
 
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