GregS wrote:
In article ,
(GregS) wrote:
Wondering if anyone is familiar with this series. I was
testing it out and the bias circuitry is not
functioning. There is shown on the schematic a bias transistor
along with one diode and pot.
There is no bias transistor on the two stages, just looks
like one diode. I intend on adding a diode or two to get it going.

There is a place on the boards for the transistor, but it was never
there.


Just to clarify. You can see the holes in the board for the
transistor, but the copper
is solid on the back plane. I don't figure how it could have worked
right
from the factory. The diode under the driver heatsink seems normal,
about 6 volt drop. I might need at least 4 diodes in addition to the
one.
H709 is MISSING.

http://zekfrivolous.com/misc/marantz2275.JPG

greg

If both channels are missing that transistor, and one of them works
properly, then it probably was meant to be like that. You can see in the
schematic that there is still a path from the base of H713 to the base of
H714. If anything, H709 would lessen the voltage between the two points and
decrease the bias even more. What is the reference number of the diode which
you say has a 6 volt drop?

--
David Farber
David Farber's Service Center
L.A., CA