Tempest diag screen

Zinfer

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I know I should just look this up but just to confirm - is this high pitched noise and 1 coming from the settings that turn on or off a phantom middle coin mech? Disregard the M - I've already replaced the ALU's and that is now fixed.

IMG_1387.jpg
 
You will get a high pitched sound when switches are pressed. Looks like the center coin mech input is stuck. Since it's not used or wired that would mean the input or output on the board is shorted to ground.

Check pin 13 of the ls244 @ R9 to see if it's high or low. Should be high.
Then check pin 7 same chip should be high as well.

If 13 is high, and 7 is low then the ls244 is most likely bad.

You can also check the pull up resistors R71 470 ohm for +5 and R65 1kohm for +5 maybe it's a cold solder joint.

You can always inject a +5v signal on pin 7 to see if it clears.
 
Thanks alot Talon. This probably happened when the ALU's blew. I'll check it out.
 
You will get a high pitched sound when switches are pressed. Looks like the center coin mech input is stuck. Since it's not used or wired that would mean the input or output on the board is shorted to ground.

Check pin 13 of the ls244 @ R9 to see if it's high or low. Should be high.
Then check pin 7 same chip should be high as well.

If 13 is high, and 7 is low then the ls244 is most likely bad.

You can also check the pull up resistors R71 470 ohm for +5 and R65 1kohm for +5 maybe it's a cold solder joint.

You can always inject a +5v signal on pin 7 to see if it clears.

7 Measures both High and Low, 13 measures low. So looks like I'll be ordering me some 74LS244's. I crossed 7 and it does clear for about 1 second, then it returns to the same state. I checked over the resistors both visually and took readings, all seemed fine there.
 
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Well it looks like to me pin 1 is on the bottom right of the chip as your looking at the board from the rear of the cabinet. I counted 7 to the left and measured, got both high and low. Up to pin 13 moving from left to right now, both high and low. Pin one is on the bottom right corner right?

74244pinout.gif
 
Yea darnit Sam. After I posted that I went and looked it up so as to not look like a dope. Then I went and edited my post. Now you went and ruined it. :eek:
 
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