Trouble Shooting The First Stage Differential Amplifier

Spenser

AK Subscriber
Subscriber
For this discussion, please refer to pages 39-43 of the below-linked

TECHNICAL GUIDE FOR SERVICE
TROUBLE SHOOTING METHOD
O.C.L. MAIN AMPLIFIER CIRCUITS
PIONEER
SERVICE DEPARTMENT INTERNATIONAL DIVISION

(Note: O.C.L acronym means -- love this -- Output Capacitor-Less.)
Three questions:

1. Is this a good practice for "...trouble shooting the the first stage differential amplifier..." that can be used with most, direct coupled push pull integrated power amplifiers? Right now I am thinking of it as pertains to a Pioneer SX-939 with a suspect, "long tailed pair."

2. Is it necessary to disconnect the output transistors?

3. What happens if you don't?

Thanks!
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http://www.kallhovde.com/pioneer/ocl-amp-techguide.pdf


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This is a good example of the training Pioneer, sansui and many others provided for their dealers who signed up as a warranty repair station.

The technical content is excellent and applies to mamy models beyond Pioneer.

Lastly, to the question of removing the final stage devices, they carry the large currents. As the document states, by removing the final stafe devices, the amp will atill operate but up to about 1 watt output.

Cheers,

David
 
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