5v on Tempest .6v at board

manadams

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Problem:

5v measures .6v at board with no led lit, no blinking start buttons or screen image.

What's been done and checked:

All voltages on power brick test good
All voltages on ar-II test good with board disconnected, ar-II was rebuilt 4 months ago with Bob Roberts kit.
Board interconnect continuity checked and pins re-flowed
all new caps on boards
no wires grounding out on coin door or underneath control panel

My next guess other than something shorted on the board is something on the ar-II failed that wasn't replaced in the rebuild kit. Does Q1, the 5v volt linear voltage regulator fail often?
 
The AR is the first thing to suspect.

If you rebuilt it with a Bob Roberts kit, check to see if the 2N3055 (the big bottlecap transistor in the middle of the heatsink) says 'Toshiba' on it, in red.

If so, it may be bad. Apparently Bob had a bunch of bad counterfeit 3055's, which have been failing for a lot of people. I've seen a couple myself on AR's that folks have sent in for repair.

If it's not that, then yes, it's possible the LM305 regulator on the AR is bad. It's not common, but I have seen a few ARs that have read ok with no load, but fail under load (and even ones that are ok at a light load, but fail at full load, which is why it's important to load test them.)

If you have any other Atari game that uses an AR-II-02 or AR-II-04, you can try swapping them, to confirm it's actually the AR. (Tempest is documented as needing a -02, but it actually only needs a -04, so either will work.)

You can also test to see if the board has any dead shorts, by measuring the resistance between +5V and ground. It probably varies from board to board, but I just grabbed a random good board off the shelf, and it measured about 400 ohms.
 
Last edited:
The AR is the first thing to suspect.

If you rebuilt it with a Bob Roberts kit, check to see if the 2N3055 (the big bottlecap transistor in the middle of the heatsink) says 'Toshiba' on it, in red.

If so, it may be bad. Apparently Bob had a bunch of bad counterfeit 3055's, which have been failing for a lot of people. I've seen a couple myself on AR's that folks have sent in for repair.

If it's not that, then yes, it's possible the LM305 regulator on the AR is bad. It's not common, but I have seen a few ARs that have read ok with no load, but fail under load (and even ones that are ok at a light load, but fail at full load, which is why it's important to load test them.)

If you have any other Atari game that uses an AR-II-02 or AR-II-04, you can try swapping them, to confirm it's actually the AR. (Tempest is documented as needing a -02, but it actually only needs a -04, so either will work.)

You can also test to see if the board has any dead shorts, by measuring the resistance between +5V and ground. It probably varies from board to board, but I just grabbed a random good board off the shelf, and it measured about 400 ohms.

I will try all of that, thanks for your help.
 
Glad you got it fixed. I was going to say I have found a couple of original 2N3055's recently that have tested good with no load but drop to a volt or 2 when hooked up to a board.
 
The AR is the first thing to suspect.

If you rebuilt it with a Bob Roberts kit, check to see if the 2N3055 (the big bottlecap transistor in the middle of the heatsink) says 'Toshiba' on it, in red.

If so, it may be bad. Apparently Bob had a bunch of bad counterfeit 3055's, which have been failing for a lot of people. I've seen a couple myself on AR's that folks have sent in for repair.

If it's not that, then yes, it's possible the LM305 regulator on the AR is bad. It's not common, but I have seen a few ARs that have read ok with no load, but fail under load (and even ones that are ok at a light load, but fail at full load, which is why it's important to load test them.)

If you have any other Atari game that uses an AR-II-02 or AR-II-04, you can try swapping them, to confirm it's actually the AR. (Tempest is documented as needing a -02, but it actually only needs a -04, so either will work.)

You can also test to see if the board has any dead shorts, by measuring the resistance between +5V and ground. It probably varies from board to board, but I just grabbed a random good board off the shelf, and it measured about 400 ohms.

Pretty awesome!
 
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