Hello,
I am attempting to repair a Olympus BX40 microscope in Honduras with a BMET working here at the hospital. It has broken several times in the past, and the technician has repaired it by replacing resistors and MOSFETs. Right now, the burnt component is a resistor labeled "R10" on the board. It is in series with the gate of a MOSFET, and has a value of 0.33 ohms. It has burned three times now, but with several weeks or months between each burning.
Any idea what is going on here? It seems like too much power is being pushed through this resistor and into the gate of the MOSFET, since the resistor and connected MOSFETs are the components that burn. I'm not sure if this is a design flaw or a result of the length of service time and other conditions the machine has been subjected to. Would it make any sense to increase the power rating and/or resistance of the resistor? I've built MOSFET circuits before where there is no resistor in series with the gate, but in this case it seems like too much power is being pushed through the gate, so some sort of resistor seems necessary. Any ideas would help.
Justin
