Marantz 2325 P700 Driver Mystery Diodes?

[deltalight]

I am currently restoring a Marantz 2325. The P700 Driver boards are different. One of the boards has two DO-41 glass diodes connected from the emitter resistors to J702 and J708. [see photo]

Can someone clue me in as to what these are for? Is this a factory protection mod or???

 

[wlhd1610]

Flyback oscillation protection diodes I believe.

I've seen them on quite a few 2325's ,usually both amp boards.
And yes they were a factory recommended modification.

Tom Williams(catrafter) wholeheartedly endorses their installation.

He should chime in shortly with the full skinny on them!

Bob

 

[catrafter]

The fly back diodes shunt back EMF around the output devices so that they aren't damaged. Speakers can be highly reactive loads.

Tom

 

[Wabajig]

Those diodes are not in my schematic. Does anyone have a part number, or know the value? Are they both the same?

 

[Autobahn]

http://audiokarma.org/forums/index.php?threads/flyback-diodes.731084/#post-9889525