Fix: Atari A035220-02 steering board

KenLayton

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Just came across a problem with the steering board # A035220-02 typically used in the Atari "Super Sprint" and other Atari games.

Symptom: No steering control, as if the steering board was not even connected.

Cause: Broken foil trace at the connector at pin 4.

Solution: Ran a jumper wire from the foil trace and wrapped it around connector pin 4 to restore the connection.

See the attached pictures and schematic.

Other general information: These boards typically have a 100 ohm to 150 ohm @ a quarter watt resistor installed. They use a # K-2126 Optocoupler unit.
 

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Sorry for the thread resurrection, but firstly a big shout out to Ken for documenting these optic boards. I haven't seen much info about them. Here's a repair log from my recent fix.

Symptom: No steering control, as if the steering board was not even connected.

Cause: Unknown.

Solution: Unknown.

I know, helpful right? On my recently acquired Championship Sprint, the Player2 (red) wheel appeared dead.

1. I first made double and triple sure the 4-pin was oriented on the optic board properly.
2. Next, I tested continuity on the 'bad' optic board from the pins to the solder points. AOK.
3. As luck would have it I had another CP completely parted out, so I swapped in another optic board. That didn't work.
4. I then swapped P1 and P2 boards and P2 STILL didn't work, while P1 STILL did.
5. This made me think there was something wrong with the harness or connection to the CPU board, so luckily I had another harness and used it. NO DIFFERENCE.
6. Now I'm concerned that the two +5's coming from the CPU board aren't hot, so I measure those. Both AOK.
7. This is where it gets strange. I took the harness completely off the CP so it would be easier to work with, turned the game on, and manually went back and forth with the encoder hub around the optic board. THAT WORKED.
8. Reinstalled the harness onto the CP and tested - AOK.

I really don't know how it became a problem, or how it was fixed. I'm thinking I scraped enough oxidation off the harness when measuring voltage that it finally made a decent connection? It sounds like a "loose nut behind the control panel" problem which I have no problem admitting - but I double and triple checked wiring and orientation. I'm just glad to have P2 working now.
 
One problem I've found for a "No steering" symptom as if the board is not connected is this:

Look closely at the steering/trackball board. Notice that BOTH of the LED (light emitter) sections are wired in SERIES with each other. That means if one of the LEDs inside the opto coupler unit dies, it kills power to the other LED. Hence the unit appears dead. The phototransistors inside the coupler unit then have no light at all getting to either of the phototransistors. So no light = no movement.

This also applies to Atari # A035220-01 version boards which were typically used in Centipede trackball units.
 
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I had one of these go bad when I cleaned it. fairly certain the traces were still good. I was able to source some replacements on the cheap instead.
 
Some of those steering/trackball boards were shipped with type OPB2208 optical couplers installed. Others were shipped with K2126 couplers installed.
 
I can confirm that optocoupler # OPB2208 is directly interchangeable with type # K2126. So you can use either type on the A035220-02 and -01 boards.
 
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The value of the resistor is the only difference from what I remember. On one board it was 100 ohms and the other was 150 ohms. Really doesn't affect operation.
 
I can confirm that optocoupler # OPB2208 is directly interchangeable with type # K2126. So you can use either type on the A035220-02 and -01 boards.

I'm curious if anyone has a source for either of these parts?
 
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