Output Sections
Top: output transistors and heatsink removed prior to
removing the board.

The left channel of this unit was
smoked!!!
A catastrophic failure took out much of the components and
burned the board.

* both output transistors
* one emitter resistor
* both driver transistors
* R768 and R771

I contemplated rebuilding this board. The trace side was still in
good shape. I ordered all the parts that needed replaced. But
when it came down to it... I could not do it. I could not put this
board back into the unit. So I relegated it to the parts bin.





I used another board that I pulled from another unit (below)
It is common for lower wattage units to be driven to
their limits. Lets face it, 30 watts does not allow for a
lot of head room. At moderate listening levels 30
watts is sufficient. Push them just a little harder and
the unit is giving all it has. Components start to heat
up. When I get a board that has failed I have to
question the condition of any componet that will run
hot when driven hard.

Driver Transistor:
I used my last set of new NEC 2SC959/2SA606 on the
left channel (long out of production). The right one
kept its originals. All other components replaced on
the left, were replaced on the right as well.

Emitters:
The emitters can take a lot of abuse under the
condition described above, and since there was one
known bad one I decided to replace all the emitters.
The replacements are a set of 5W wire-wound
resistors (3W originals).  These are a close match for
the original emitters (which are a type of wire wound
resistor as well... the core is different). It would be
nice if there was a source for the old style emitters.
But, I am afraid there is not. However, inductance is
not an issue for small values such as these (.24
ohms), so... no problem.

Resistors:
Any resistor that is directly in the current supply path
of the output transistors were replaced.
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