Atari ARII missing 12V - Manufacturing Fault?

Womble

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Here's a weird question for the ARII folk on here, had an ROTJ on the bench recently, and it came with it's original ARII (identical serial numbers). The board had logic faults that are now fixed, but the owner sent the ARII as he was getting 0V on the 12v rail and he took this to be a sign the ARII was faulty too.

The ARII is a A035435-02 which seems to be correct, the cabinet only uses the -5V output, leaving the +12v, the +22V and -22V unused, as the ROTJ cabinet doesn't use 12v anywhere.

But on this ARII the 12V rail would never have worked, as the power resistor R25 has been fitted in the wrong location, it should be connected to the other pad to the left of where it is currently.

IMG_3684small.jpg
With it fitted between those two pads there is an air gap in the circuit leaving C22, C23 and the 7812 isolated.


schematic.jpg

In this location the legs of R25 are actually connected together, so it is completely pointless.

IMG_3685annotated.jpg

The solder on R25 looks original. especially on the parts side ( the flash makes them look a bit newer on the solder side) but the most telling sign that this is original is the correct pad is is still filled with factory solder, even with the dimple from the wave solder bath. R25 looks identical to the power resistors on other ARIIs I have, where the legs are correctly spaced and installed to the right pads. So I don't think this was taken off and then put back in the wrong place, the legs aren't long enough, and they have the slight bend to aid placement still intact.

If this was an attempt to disable the 12V they could have achieved the same thing by leaving R25, C22, C23 and the 7812 out entirely, saving the cost.

When R25 is lifted and connected to the correct pad the 12V line lights up and the ARII will happily run my Star Wars cabinet, which needs all the voltages present on the A035435-02 variant.

What do you think? Manufacturing fault? Possible a dodgy batch used on a game where the lack of 12v didn't matter.
 
Certainly does look like a factory installation error to me as well. The resistor's legs even have the insertion machine bend in them to hold them up off the board.

I can't recall how many Atari games didn't require +12v but it certainly wouldn't surprise me if they got a batch in from assembly, realized the error, and then waited to use them in a game that didn't require it.
 
This is semi-common with Atari stuff. You often see parts missing, or incorrectly installed, when they're non-critical to the operation of the game.

Atari's QA was minimalist. They checked to see if the game worked, and that's about it. So things like this slipped through. I've seen an AR like that one myself, but you also see stuff like bypass caps missing on game boards, etc. If it wasn't bad enough to make the game not work right, it slipped by.
 
This is semi-common with Atari stuff. You often see parts missing, or incorrectly installed, when they're non-critical to the operation of the game.

Atari's QA was minimalist. They checked to see if the game worked, and that's about it. So things like this slipped through. I've seen an AR like that one myself, but you also see stuff like bypass caps missing on game boards, etc. If it wasn't bad enough to make the game not work right, it slipped by.
Yep, that's pretty minimal QA.

I have seen QA like that cause serious issues later when 3 simple jumpers were mis-placed one slot to the left, and caused a 480 V circuit breaker to trip when it shouldn't have by defeating the normal trip curves.

QA is more important than even the QA people think sometimes.
 
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