Marantz PM-50 Amplifier Repair (Replacing the STK and Transistors)
I'm attempting to repair my very own 1990s vintage Marantz PM-50 amplifier that had some problems with the hybrid preamplifier overheating and subsequently damaging some of the power amp transistors. In retrospect, it may all have started with the loose connection on the STK (I first discovered it a bit into this video) that caused the components to fail due to intermittent current flow and voltage peaks.


I'm exchanging the faulty STK 3062 MK IV for a STK 3082 MK III that has a slightly higher voltage rating. After adjusting the idling current there's no problem whatsoever with that. It sounds great and runs way cooler than the old STK.

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