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Repairing Atari's 1998 California Crusing arcade video game
By, William Stephens
(clicking any picture in this article will bring up an enlarged version)

CAUTION
The procedures outlined in this article are very dangerous for the clumsy and inept among us. If you think this applies to you then read but don't do, you might kill yourself.

When it first came in, this game worked with some exceptions.

First, the brake was set continuously, the force feedback mechanism on the steering wheel was not working and the monitor had tiger stripes and "funny" color banding... actually, not too bad overall.

The brake was fixed by replacing the brake potentiometer which had gone flakey due to the repeated use and vibration... it just wore out!

The monitor was fixed by re-capping the Wells-Gardner K7501 25" color monitor chassis, although the monitor is only 7 years old, it's old enough to need a cap-kit. Most electrolytic capacitors have a work life of between 2,000 and 8,000 hours, if you do some simple math you will see that these things exceed their rated lifes in less than a year of arcade operation. This game has seen the rounds and certainly has more than 2,000 hours of "on" time by now.

After installing the cap-kit, I re-aligned and adjusted the monitor for nominal operation. This eliminated the tiger striping and color shifts and once done, the monitor looked and performed as if it were brand new.

Now I'm down to the last problem... the steering. The reason that the force feedback for the steering did not work was because it was unplugged. Upon plugging the motor controller in, the wheel snapped sharply all the way left and held there with some force. No wonder why it was unplugged.

Obviously there is a motor controller problem, unfortunately, I have no schematic for this game so it looks as if I am going to have to reason this one out using my limited knowledge of motor control circuits.

I removed the motor controller circuit board from the game and took it over to the workbench to check some of the boards components. In examining the board I find that there are really not very many components, so I start with the easy to check ones and proceed to the more difficult later on. First the fuses check out OK as do the diodes. The resistors look OK as do the capacitors so being lazy and not wanting to unsolder more, I skip onto the only active component on the board, the TO-3 cased semiconductor nestled in the center of a great big heatsink. This has got to be something important.

It's an LM12CLK which turns out to be an 80 watt operational amplifier, here's a breif technical explaination from the datasheet I found on the Internet.

The LM12 is a power op amp capable of driving 25V at 10A while operating from 30V supplies. The monolithic IC can deliver 80W of sine wave power into a 4 ohm load with 0.01% distortion. Power bandwidth is 60 kHz. Further, a peak dissipation capability of 800W allows it to handle reactive loads such as transducers, actuators or small motors without derating.

This thing is the actual motor controller for sure, now all I have to do is see if it's working properly. I imagined that seeing that you can swing voltages both positive and negative using an operational amplifier, this must be it's purpose... take 48 volts and make it -24volts and +24volts to spin or thrust the force feedback motor left or right depending on a small signal from the main circuit board. I should see a small varying voltage at the inputs and up to +24/-24 volts on the output with the game running.

Under test, +24 volts was present at every lead of the amplifier... this is not right, it looks to be shorted out. I guess I found my culprit. Replacing the LM12CLK fixed the forced feedback steering problem, finally everything operates correctly.

--William Stephens


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