Sooo, what would cause D3 to unsolder itself off the MPU?

[RILaw]

Picked up this S+ project recently, had a 65-3 code (After I replaced a bad CC and coin optic I'm at this stage).  Found one of the large diodes chilling on the bottom of the machine.  So I soldered it back in (D3) and still had a 65-3.... turn key, 65-1, press reset, 65-0 and smell of burning....D3 unsoldered itself again     So I just looked closely at the cpu pcb to see if a quarter or anything was shorting anything...Nothing.  Checked wires etc.....  Soooo, any ideas??

Thanks

[Crash0]

Is D3 anywhere near the transformer?  If so, may want to check output on it, see what kind of voltage it's putting to the board.

[RILaw]

Is D3 anywhere near the transformer?  If so, may want to check output on it, see what kind of voltage it's putting to the board.

No, its the one big diode by itself near the top of the pcb, not one in that group of large diodes.

[LINDAM]

It sounds like your D3 is part of the power supply bridge and may be bad. have you check it to see if it's still a diode?

[RILaw]

It sounds like your D3 is part of the power supply bridge and may be bad. have you check it to see if it's still a diode?

Sorry, yes, tests good on DMM.  Thanks

[LINDAM]

By looking at one of my S+ PCB's, it looks to be the regulator for the +5 Volt supply for the board. Should be a 1N6373.

[Crash0]

maybe try testing transistors, they often regulate voltage
Lol what he said^