Why won't my MCR game boot?
I get this question alot, and i'm tired of typing the same thing over and over.
For an MCR game to boot, you need several things.
+5v. This should be measured at one of the caps on the corner of the ssio.
Vbatt- this should be +5v as well when the game is powered on. If not the game will not boot. Powered off, it should read the backup battery voltage minus around .5v. If vbatt is low or missing the pcb will not boot as it provides 5v to the cpu ram.
/Reset- this must start out logic low (.4v or less) and stay low for until the +5v is stable, and then go high (logic level of 2.7v or higher. On MCR games it will often be well over 5v). A lot of arcade games have the reset generator circuitry onboard the pcb. MCR games do not. /Reset is produced on the 90412 power supply. This is critical, as a perfectly good pcb will not boot if the 90412 is bad.
Other things needed for the game to fully work -
12v. 90412 have 2 sets of 12v on them. One is regulated and goes to the pcb, the other unregulated and goes to the sound amp. If either is missing, the game will not have sound.
So how do i test all of this stuff?

+5v - measure at one of the caps on the corners of the ssio. Red Square+, Black Square-
/Reset - Pin 26 of the z80 at A12 Purple Line+, Black Square-. Unless you power cycle, this should be around +5v. If it is logic low, you have a reset problem on the power supply. Also check that dipswitch 10 at b3 is off.
12v - any of the 3 tantalum caps circled in red. + is the tapered side. Or Yellow line+, Black Line- of the lm3900 at D3. (D3 pin 7-, pin 14+)
VBatt. This is harder to test. Black Square -, or black line on cpu image-. Blue line on cpu image +. You may need to unplug everything but the J1 power connector, and snip a few zip ties to get the pcb pulled out enough to be able to test this. (J1 pin 6 or 7-,pin 16+).

I get this question alot, and i'm tired of typing the same thing over and over.
For an MCR game to boot, you need several things.
+5v. This should be measured at one of the caps on the corner of the ssio.
Vbatt- this should be +5v as well when the game is powered on. If not the game will not boot. Powered off, it should read the backup battery voltage minus around .5v. If vbatt is low or missing the pcb will not boot as it provides 5v to the cpu ram.
/Reset- this must start out logic low (.4v or less) and stay low for until the +5v is stable, and then go high (logic level of 2.7v or higher. On MCR games it will often be well over 5v). A lot of arcade games have the reset generator circuitry onboard the pcb. MCR games do not. /Reset is produced on the 90412 power supply. This is critical, as a perfectly good pcb will not boot if the 90412 is bad.
Other things needed for the game to fully work -
12v. 90412 have 2 sets of 12v on them. One is regulated and goes to the pcb, the other unregulated and goes to the sound amp. If either is missing, the game will not have sound.
So how do i test all of this stuff?

+5v - measure at one of the caps on the corners of the ssio. Red Square+, Black Square-
/Reset - Pin 26 of the z80 at A12 Purple Line+, Black Square-. Unless you power cycle, this should be around +5v. If it is logic low, you have a reset problem on the power supply. Also check that dipswitch 10 at b3 is off.
12v - any of the 3 tantalum caps circled in red. + is the tapered side. Or Yellow line+, Black Line- of the lm3900 at D3. (D3 pin 7-, pin 14+)
VBatt. This is harder to test. Black Square -, or black line on cpu image-. Blue line on cpu image +. You may need to unplug everything but the J1 power connector, and snip a few zip ties to get the pcb pulled out enough to be able to test this. (J1 pin 6 or 7-,pin 16+).

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