fourth flash bis sixth flash
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Fourth Flash Completed:
The Fakers Guide: a fourth flash means the U10 PIA (6821) is good.No fourth flash means U10 (6821 PIA) or its socket are bad. Or battery corrosion had broken a trace going to U10.Or the chip leading to U10 is bad, which is U20 (4502).
Techno Guide: The U9 CPU chip now tests the first 6821 PIAchip. There are two of these chips on the MPU board, which areidentical and interchangable. The test for both is the same.
To determine if a PIA chip is good, the U9 CPU does the following:
Also check and make sure that the MPU connector J1 and the lamp driver connector J1 are not mixed up! These two connectors are about 4 inches apart, and are keyed the same. If only three MPU LED flashesare seen, this problem can also sometimes show the score displays with an '8' or a '9' in the hundreds place.
Also I recently fixed a game (Bobby Orr Power Play)where sometimes it would not get the fourth MPU flash,but sometimes it would get all seven. If it did boot, the score displays wouldflicker and only show some of the six digits.The problem was a trace going to U10 on the component side of the MPUright near the battery that was intermittent from corrosion.After I cleaned up the corrosion (sanded and neutralized) and repairedthe broken trace (it was obviously open after sanding), the MPU booted andthe game worked correctly.
Fifth Flash Completed:
The Fakers Guide: a fifth flash means the U11 PIA (6821) is good.No fifth flash means U11 (6821 PIA) or itssocket are bad. Note the flipper enable relaywill usually click on/off at about the fifth flash.The lack of a fifth flash could also be a bad resistorconnecting to U11 like R134. Another issue could be a bad score display,which can cause the MPU board to stop during the 5th LED diagnostics.Disconnecting all the score displays (power off), then reconnectingthem one at a time (power off) and rebooting can help identify a bad displaythat is dragging down the fifth MPU LED flash.
Techno Guide: Same test is performed on U11 as was performedon U10. See above.
Sixth Flash Completed*:
The Fakers Guide: a sixth flash means the PIA at U11 (6821) andthe U12 timer (5550 chip is good. No sixth flash means either PIA U11 (6821) or its socket is bad, or the U12 (555) timer is bad.Lack of the 6th flash (five flashes only) can also mean a problems withthe zero-crossing detector. Often this isthe MPU board's R113 resistor (2k ohm, near the J4connector) is open. This resistor takes the 43 volt DC coil power tothe zero-crossing detector circuitry and normally runs hot. Hence itmay eventually go open, so check it if only 5 flashes from the LED are seen.Thanks to Ray J. for this tip.
Techno Guide: The U9 CPU chip monitors PIA2, port CA1 (U11). Iftransitions from high to low are detected, the CPU decides the DisplayInterrupt Generator is working. If U12, a 555 timer, or any associated circuitcomponent fails, the CPU will not flash the LED the sixth time.
* Note on Baby Pacman and Granny and the Gators, this flash stepis skipped and not tested.
Fourth Flash Completed:
The Fakers Guide: a fourth flash means the U10 PIA (6821) is good.No fourth flash means U10 (6821 PIA) or its socket are bad. Or battery corrosion had broken a trace going to U10.Or the chip leading to U10 is bad, which is U20 (4502).
Techno Guide: The U9 CPU chip now tests the first 6821 PIAchip. There are two of these chips on the MPU board, which areidentical and interchangable. The test for both is the same.
To determine if a PIA chip is good, the U9 CPU does the following:
- The CPU accesses, by means of input RS0, RS1, CS0, CS1 and CS2each of the two full byte registers used to store the port initializationinformation. If does this, one register at a time. After it completesthe first register, it repeats for the second. It goes through 256tests similar to that used to check each byte in U7 (second flash). Ifeach time the CPU writes a word into the register, it can read the sameword back, it continues to test until completion.
- The CPU accesses, by means of input RS0, RS1, CS0, CS1 and CS2,each of two full byte registers used as data output registers whenPA0 to PA7 and PB0 to PB7 are used as outputs. It does thesame type of test on each register as described just above. Again ifno faults are found, the test is continued until completion.
- The CPU then accesses, by means of input RS0, RS1, CS0, CS1 and CS2, the two ports CA2 and CB2. The port is initialized as an output. The portis then written into to see if it can store a "1" and then a "0".
Also check and make sure that the MPU connector J1 and the lamp driver connector J1 are not mixed up! These two connectors are about 4 inches apart, and are keyed the same. If only three MPU LED flashesare seen, this problem can also sometimes show the score displays with an '8' or a '9' in the hundreds place.
Also I recently fixed a game (Bobby Orr Power Play)where sometimes it would not get the fourth MPU flash,but sometimes it would get all seven. If it did boot, the score displays wouldflicker and only show some of the six digits.The problem was a trace going to U10 on the component side of the MPUright near the battery that was intermittent from corrosion.After I cleaned up the corrosion (sanded and neutralized) and repairedthe broken trace (it was obviously open after sanding), the MPU booted andthe game worked correctly.
Fifth Flash Completed:
The Fakers Guide: a fifth flash means the U11 PIA (6821) is good.No fifth flash means U11 (6821 PIA) or itssocket are bad. Note the flipper enable relaywill usually click on/off at about the fifth flash.The lack of a fifth flash could also be a bad resistorconnecting to U11 like R134. Another issue could be a bad score display,which can cause the MPU board to stop during the 5th LED diagnostics.Disconnecting all the score displays (power off), then reconnectingthem one at a time (power off) and rebooting can help identify a bad displaythat is dragging down the fifth MPU LED flash.
Techno Guide: Same test is performed on U11 as was performedon U10. See above.
Sixth Flash Completed*:
The Fakers Guide: a sixth flash means the PIA at U11 (6821) andthe U12 timer (5550 chip is good. No sixth flash means either PIA U11 (6821) or its socket is bad, or the U12 (555) timer is bad.Lack of the 6th flash (five flashes only) can also mean a problems withthe zero-crossing detector. Often this isthe MPU board's R113 resistor (2k ohm, near the J4connector) is open. This resistor takes the 43 volt DC coil power tothe zero-crossing detector circuitry and normally runs hot. Hence itmay eventually go open, so check it if only 5 flashes from the LED are seen.Thanks to Ray J. for this tip.
Techno Guide: The U9 CPU chip monitors PIA2, port CA1 (U11). Iftransitions from high to low are detected, the CPU decides the DisplayInterrupt Generator is working. If U12, a 555 timer, or any associated circuitcomponent fails, the CPU will not flash the LED the sixth time.
* Note on Baby Pacman and Granny and the Gators, this flash stepis skipped and not tested.
Alive and kicking