Crown D60 Amplifier Problem

[Glenn A. Davis]

I just received a basket case Crown D60 amplifier that had several of the
output transistors replaced. It has been years since I looked at one of
these and do not remember the transistor types. I would appreciate if some
one will send me information on suitable replacements and if possible a
schematic. Also the serial number is18679 if this helps. From some of the
components it appears that it is circa 1977 or 78.

This amplifier appears to have a quasi-complementary output stage using dual
supplies and NPN transistors in the power stage. Channel 2 have what appear
to be relabeled power transistors from Motorola labeled 4152. Channel 1 has
two different transistors which are MJ802 and 2N3055. The MJ802 appears to
have about twice the gain of the 2N3055 which is probably one of the reasons
the output stage repair was abandoned. On a curve tracer the MJ802 has
similar gain to the relabeled ones, however they are different. In addition
the driver transistors are both NPN and have slightly different I-V curves.
I suppose that one of these overheated during the original failure.

If any one has any information that would help me, please let me know.

Thanks,

Glenn A. Davis
FAX: 612-368-1168

[Stephen Sank]

You can use either 2N3773 or MJ15003 for the output xstors. You could
also use 2SD424. Pretty much anything with enough V & I will work if
it's not something bizarre.

[Jack Schidt]

Start by contacting Crown, in Elkhart Indiana, for a schematic. You are
shooting in the dark.

JS.

Glenn A. Davis wrote in message <7bcfei$1p...@enews1.newsguy.com>...

[DAVID KATZ]

I have an old (ca. 1975) D-60 manual, with schematics & parts list, I'd send
you for $5. The output transistors are listed as "2N3055 selected" for
s#<13000, then superseded by Motorola CPN4152, with a few R and C changes
for stability. Drivers are 2N6175. The "Principles of Operation" section
implies that the drivers are barely biased into class AB by R111/211, while
the output Qs are off until >100mA output is needed.
Dave