Ensoniq ESQ-1 Not powering on

Hey Guys,

Long Story Short;

Bought a broken ESQ-1 Metal Version 240v (Australia)
Previous owner reported blown fuses pre and post battery replacement
Got it home and no blown fuses, no signs of life
When Mainboard is disconnected from power board screen goes into self-test mode
Voltages on mainboard average except +5V Digital which is +1.8v under load or 11.7v from Power Board

at this point my limited experience with synths has stopped me from being able to diagnose the issue but presumably something is pulling more power than it should be? possible Mainboard issue? Synth gods are mad at me?

who knows


UPDATE so R1 and R2 on the power circuit that directly lead to the mainboard are burnt
i replaced them but the same issue persists. does anyone have any voltage measurements i an use to test the tracing?

These are difficult to fix for an experienced tech without a working unit let alone a novice. You need to isolate whether the problem is on the display board or the mainboard. I’d be looking out for a working one then use that to figure out the rest. All the schematics are online, search around.