Electronics > Beginners
Repair of HiFi Amp - Transistor as a voltage regulator
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riffmaker:
Hi All,

I am currently repairing an audio amplifier (Harman Kardon TA600), I discovered that one transistor was dead on the power supply board (I attach the diagram from harman, I highlighted in red the transistor that is not working anymore). The only information written in the user manual for this component is : 43029387 NPN power silicon. I tested each of the pin with a voltmeter before removing it, and it was 0V a the emitter

I desoldered the component and I unfortunately broke a pin, but I attach you a picture

Does anyone knows how I could replace it ? Which modern reference of transistor could fit ?

Thank you
Pierre
dzseki:
Depending on the available space BD139 or BD239 would do. But the pinout of the transistor should be verified!
jackthomson41:

--- Quote from: riffmaker on February 22, 2019, 12:19:26 pm ---Hi All,

I am currently repairing an audio amplifier (Harman Kardon TA600), I discovered that one transistor was dead on the power supply board (I attach the diagram from harman, I highlighted in red the transistor that is not working anymore). The only information written in the user manual for this component is : 43029387 NPN power silicon. I tested each of the pin with a voltmeter before removing it, and it was 0V a the emitter

I desoldered the component and I unfortunately broke a pin, but I attach you a picture

Does anyone knows how I could replace it ? Which modern reference of transistor could fit ?

Thank you
Pierre

--- End quote ---
yeah BD139, BD140 or BD137, they all can work and which one you select compare its pinout with yours.
riffmaker:
Thank you for your answers !

Unfortunately, I checked with the original pinout, that doesn't fit... (I need the base pin at the center)

I found this reference : ZTX692B (datasheet attached)
Do you think that it could work ?
Benta:
That looks a lot like a Motorola MPSU06 (NPN) or MPSU56 (PNP). Common in amps from the 80s. If you're lucky, you might find NOS parts somewhere.
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