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Old 09-03-2020, 07:06 PM   #9
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Default Re: HiPro HP-P3017F3 rev:03 [Dell H057N] - capacitor repair

Originally Posted by PeteS in CA View Post
In the case of desktop PSUs such as the one discussed in this thread, fan speed is usually adjusted using a thermistor and opamp to control the DC voltage to the fan.
This HiPro uses a "simple" thermistor + transistor circuit as a fan controller. I haven't began to trace it yet, but I did find the fan "driver" transistor... and it's (sigh) the usual TO-92 package. Probably going to run very hot when the fan is set to run between 5-7V. At least the fan is only rated for ~160 mA @ 12V. The more powerful fans tend to cook TO-92 transistors when they are used as a series linear regulator.
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