In article ,
Bob Landry wrote:
Just deleted rec.audio.misc. since it seems to be populated by folks who can't
seem to find *.*.politics. This groups seems to have folks who are actually
interested in and knowledgeable about audio. I'm in the "interested" group, but
not in the "knowledgeable" group.
I have a Dynaco SAT-4 that I bought used off eBay, along with a Carver power
amp. I seem to have recently lost the right channel; moving the balance knob all
the way to the right has no effect. I'm running the Carver into 2 Polk speakers,
where I've used all 4 terminals on each, running two lines into each of the 4
outputs on the Carver. I've checked and rechecked the connections, and they're
all done the way the Polk instructions describe.
Is there any way to tell whether the problem is with the Dynaco or the Carver
without taking it to a shop? The drop off occurs with the CD player and the FM
tuner, also a Dynaco, so I think it's safe to say that the problem is with the
electronics and not the speakers, right?
The fact that it affects both the CD player and the FM tuner indicates
that the problem isn't in either of those components, or in the cables
connecting them to the Dynaco. It's "downstream"... at the Dynaco or
later... but you haven't eliminated the speakers as the possible
problem (although it's
Swap the left and right channel cable connections where they come out
of the Dynaco (with the power off everywhere, of course) and see what
the effect is.
If the problem moves to the opposite channel, then it's either in the
Dynaco, or in the Dynaco-end connectors of the cable. Distinguish
these two cases by trying a different cable... problem goes away (you
had a bad cable) or problem remains (bad Dynaco).
On the other hand, if the problem stays the same, then it's either in
the cable itself, in the connectors at the Carver end of the cable, in
the Carver, or somewhere downstream (e.g. speaker cables or speakers).
Swap the Dynaco-to-Carver cable with a known-good one to rule out a
cable problem, then figure out whether the problem is in the Carver or
the speakers.
You might have blown a fuse in the Carver, due to (e.g.) running
low-impedance speakers in parallel (creating an impedance below that
allowed by the Carver, or to having a loose strand of speaker wire
drift to where it wasn't wanted and create a momentary short circuit.
I'm not familiar with the Dynaco SAT-4 - I know of the PAS-4
(firebottle-based audio preamplifier/control center) and the PAT-4
(first-generation solid-state successor to the PAS-4). If those are
what you're referring to, I'd suggest that age may have caught up with
the device.
If a PAS-4 you might have a failed tube.
In either model, you could have an open/dirty/defective
balance-control pot, or volume-control pot, or switch. Operating the
input-selector, and tape-monitor switches a few times might restore
function if it's a dirty switch. A medium-term remedy for dirty
controls is a good squirt of a suitable control/contact cleaner into
the control (with power off!) while operating the switch or control
through its full range of motion. A longer-term cure may require
replacing the bad control.
Older Dynaco components can also suffer from dried-out electrolytic
capacitors... there are some in the signal path which can "go open"
and cut off the signal entirely.
--
Dave Platt AE6EO
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