Hello,
I have a Pioneer SX-1250 reciever from the 1970s which a local thrift
store had been about to trash. It looks great aside from a few
scratches and is pretty clean. However, the right channel is weak- it
comes in much quieter than the left. Also, the unit emits a quiet but
audible buzzing noise-not from the speakers, but from the unit itself.
Any idea what this might be? And would it be expensive to fix? I
understand these were first-class units in their day, and I would
consider repairing it if the cost were not too exorbitant

"Bill Johnston" wrote ...
I have a Pioneer SX-1250 reciever from the 1970s which a local thrift
store had been about to trash. It looks great aside from a few
scratches and is pretty clean. However, the right channel is weak- it
comes in much quieter than the left.

On all inputs? Have you tried at least exercising (and better yet:
cleaning) all the switches and pots?

Also, the unit emits a quiet but audible buzzing noise-not from the
speakers, but from the unit itself. Any idea what this might be?

If there is no hum coming out of the speakers, and the case/
components (particularly the power transformer) is not getting
particularly warm, it is likely normal mechanical hum from the
power transformer. Not all that unusual.

Or possibly the outer cabinet being moved by the magnetic
field around the transformer. Does the hum go away with the
covers off?

And would it be expensive to fix?

Do you work on equipment yourself? If you have to send it to
a repair shop I would guess that cost will range between "not
worth it" (i.e. finding a new transformer so many years after
the production run) and "unfixable at any price" (i.e. they can't
find a replacement transformer and are unwilling to do the
extra steps of removing and remediating the transformer).

Unless you value this thing at many hundreds of dollars, I'd
guess that you will find the repair estimate "exorbitant".
www.classicaudio.com says they are worth $209.50-621.00

If you want to do it yourself, you could carefully remove the
power transformer and quiet it down by tightening the bolts
which hold the laminations together. If that doesn't fix it, you
could dip it in lacquer/shelac (whatever it is they use for
transformers these days).

I understand these were first-class units in their day, and I would
consider repairing it if the cost were not too exorbitant

Only you can make that judgement call. "First class" in 1970
is likely average or below today. It has lots of bells and
whistles, but the specs seem unremarkable by today's standards.

On 2 Mar 2006 18:53:32 -0800, "Bill Johnston"
wrote:

Hello,
I have a Pioneer SX-1250 reciever from the 1970s which a local thrift
store had been about to trash. It looks great aside from a few
scratches and is pretty clean. However, the right channel is weak- it
comes in much quieter than the left. Also, the unit emits a quiet but
audible buzzing noise-not from the speakers, but from the unit itself.
Any idea what this might be? And would it be expensive to fix? I
understand these were first-class units in their day, and I would
consider repairing it if the cost were not too exorbitant


If the problem doesn't turn out to be a dirty switch, Pioneer used
Sanyo electrolytic capacitors in that unit which had a tendency to dry
out after a few years. An esr meter will readily spot the culprits.
This is a very nice receiver which had a very good tuner and
prodigious power output. chuck