I'm repairing a Tektronix 468 oscilloscope and believe I have an intermittent 5V bridge rectifier.
After the scope is off for days or hours and then powered up, I sometimes have the voltage at the output of the rectifier and sometimes I don't, but I always have the correct rectifier input. Whenever the 5V power supply is working, it always fails within several minutes. If I spray the rectifier with freeze mist or put a screwdriver blade on the rectifier (like a heat sink, I guess) the power supply will start working again (less than a minute later). When I try to wiggle the rectifier or tap it or the PCB, it doesn't affect the power supply.
The power supply uses a linear regulator with an op-amp controlling a series output transistor.
Has anyone ever seen a rectifier fail like this or should I keep looking? My experience with rectifiers has been they either work or don't. Am I missing anything? This circuit board isn't easy to get out so I can only see the component side now.
Thanks!
After the scope is off for days or hours and then powered up, I sometimes have the voltage at the output of the rectifier and sometimes I don't, but I always have the correct rectifier input. Whenever the 5V power supply is working, it always fails within several minutes. If I spray the rectifier with freeze mist or put a screwdriver blade on the rectifier (like a heat sink, I guess) the power supply will start working again (less than a minute later). When I try to wiggle the rectifier or tap it or the PCB, it doesn't affect the power supply.
The power supply uses a linear regulator with an op-amp controlling a series output transistor.
Has anyone ever seen a rectifier fail like this or should I keep looking? My experience with rectifiers has been they either work or don't. Am I missing anything? This circuit board isn't easy to get out so I can only see the component side now.
Thanks!