Repair of HiFi Amp - Transistor as a voltage regulator

[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]

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

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.

[riffmaker]

Thank you Benta, you're right that seems to be that reference !

I now have to find some on the internet... 

[6PTsocket]

Did anybody notice that the 30 volt output is labeled 29.2 volts on the same wire if you follow it onto the circuit board?

Sent from my SM-G900V using Tapatalk

[bson]

Also check C5.  If C5 is unable to hold a charge and effectively shorts, Q2 could be fried due to an excessive B-E voltage.

[alsetalokin4017]

My old Interstate (Racal Dana) F43 function generator uses those same Motorola transistors as final output. After an... er... untoward event      I was able to find NOS replacements at UTSource. They have always been good to me.