Hello everyone, I need some help from a Data East/Sega pro
(This is a Data East machine with Sega badges on the cabinet, internal is all Data East boards)
I have a Sega Frankenstein project game and I already fixed all electric problems except for one: Frankensteins head does not work.
I know that most of the times the problem is either the servo motor, or the servo board (head motion board) beneath the playfield. But that does not seem the issue here. (I think)
These are my findings so far:
-Servo board only gets the +5 volts and ground, so no clock, data or enable.
-Wiring between cpu and servo board is fine, measured continuity.
-On cpu connector cn3 I measure:
*Cpu cn3-1 = 0.067V NOT GOOD= should be enable +5 volts
*Cpu cn3-8 = 0.066V NOT GOOD= should be data +5 volts
*Cpu cn3-9 = 0.071V NOT GOOD= should be clock +5 volts
-It is not like the servo board is pulling the voltages down or something, when I disconnect the connector I still get the same voltages.
-Connectors cn1 and cn2 have the same components running to them as cn3, but they both have +5 volts on all pins and cn3 does not.
-It does not matter if I put servo test on ON or OFF, the signal stays low (0) and only flashes high (1) for a brief moment. (all while staying low (0) at the same time)
-If I put the servo test on ON or OFF, the voltage on the cn3 connector rises slightly (to max 1 volt) before dropping again.
-Connector cn2 has the enable signal, which is always high (1) and I believe correct.
-The ef6821 that is closest to cn3 has 5 volts input where it should be.
Anyone that can guide me in the right direction?
I'm guessing the problem is either the ef6821 on location 11B, or a component that is an input for it.
I do have an oscilloscope and voltagemeter but don't know where to look further.
Also posted this in the Frankenstein club, but thought I might get more answers here.