I have a non-working Turboexpress system that I got cheap off eBay. The first time I checked, the fuse blew fast and some of the old electrolytic caps had gone bad. Common issues with Turboexpress.
After replacing the electrolytic caps and putting a new fuse in, I was able to get it powered without blowing the fuse. But it still doesn't work right. When I checked the power draw, a working Turboexpress should be drawing between 300 and 400mA. The one I am trying to fix only gets 20mA so I suspect the issue may be in the power circuit. Maybe a shorted MLCC or a failed regulator chip? Many of the SMD chips don't have any marking to tell me what kind of transistor, 3 pin ICs, or such, and all of the SMD caps don't have any marking.
There are guides for caps repair, no back-light, and no sound issues but there seems to be no guide or schematic for power circuit. And my Google-fu is failing me. The best I've gotten is Turbografx-16 schematic and service manual but the power circuit is quite different as Turboexpress needed to generate negative 29 volts for the LCD and the inverter for the CCFL to light up LCD. Turbografx-16 only needs 5v to power the entire system.
So does anyone know if there are schematic for Turboexpress? Even if it's just the power supply from DC in to 5v DC + negative 29v DC + CCFL power.
PS I also searched for PC Engine GT, they are the same as Turboexpress but for Japanese market. They would have virtually identical power circuit.
After replacing the electrolytic caps and putting a new fuse in, I was able to get it powered without blowing the fuse. But it still doesn't work right. When I checked the power draw, a working Turboexpress should be drawing between 300 and 400mA. The one I am trying to fix only gets 20mA so I suspect the issue may be in the power circuit. Maybe a shorted MLCC or a failed regulator chip? Many of the SMD chips don't have any marking to tell me what kind of transistor, 3 pin ICs, or such, and all of the SMD caps don't have any marking.
There are guides for caps repair, no back-light, and no sound issues but there seems to be no guide or schematic for power circuit. And my Google-fu is failing me. The best I've gotten is Turbografx-16 schematic and service manual but the power circuit is quite different as Turboexpress needed to generate negative 29 volts for the LCD and the inverter for the CCFL to light up LCD. Turbografx-16 only needs 5v to power the entire system.
So does anyone know if there are schematic for Turboexpress? Even if it's just the power supply from DC in to 5v DC + negative 29v DC + CCFL power.
PS I also searched for PC Engine GT, they are the same as Turboexpress but for Japanese market. They would have virtually identical power circuit.
