It's fascinating to see how this discussion has developed - reassuring
to see a number of people respond with support and suggestions for my
question - a little disconcerting to see a few cases of "my answer is
bigger than yours." I'm sure you all have more pressing demands on your
time than my little question. To set your collective minds at ease, I
purchased a new Sony receiver over the weekend and am giving the old
Yamaha a respectful burial.

Thanks to all!
Greg

Mark D. Zacharias wrote:
Jamie wrote:


Half-baked gobbledygook.

1. A shorted rectifier or main filter cap would blow the fuse every
time, not just the first time.
2. The receiver in question has a DC and current detect circuit, not
a simple R/C delay for the relay.
never said it was a simple RC circuit, i think i said something on
the effects of sampling the voltage?, this implies its looking for a
desired level. and many upper end units use separate source from the
main bridge and caps to operate this little circuit!. it is very
possible for a bridge or cap to have a short with the trickle charge
R being on the AC side of the transformer into the bridge. this would
protect the fuse from being blown out again since the monitoring of
voltage never reaches its level via the low current charge Network
that is being used. if problems arise while in operation then it
would make sense for the fuse to be defective since the PSU would
have this low current R bypassed and over current would have been
seen.. defects could also lead to Audio output being shorted
which i also connected to the supply during charge up. this form of
protection is able to monitor both PSU and attached devices.
so it's very common to find fuses blown during operation and not
blow after you replace them,. this generally means the PSU has not
met its desired peak level of charge before the by pass
contactors/electronic switch are connected.


No, you never exactly said it was a simple RC circuit - but that is what is
required for a simple time delay prior to the relay activating. There is no
such circuit in the Yamaha. All it's "looking" for is an absence of a DC
offset at the output of the amplifier, and possibly excess current flow,
though I'm doubtful that feature existed on this low-end model. I have the
service manual at work, but I'm not even going to look it up because it's
really irrelevant to the point.

and this:

if problems arise while in operation then it
would make sense for the fuse to be defective since the PSU would
have this low current R bypassed and over current would have been
seen.. defects could also lead to Audio output being shorted
which i also connected to the supply during charge up. this form of
protection is able to monitor both PSU and attached devices.
so it's very common to find fuses blown during operation and not
blow after you replace them,. this generally means the PSU has not
met its desired peak level of charge before the by pass
contactors/electronic switch are connected.

is either PURE gobbledygook, or you simply have problems expressing what you
are really trying to say. I'm not trying to be insulting here, by the way,
but you have posted generic advice without labeling it as such, and that
advice:

1. Is faulty in general terms.
2. Does not apply to the specific model the original poster had, while at
least 2 or 3 other replies were from knowledgeable techs who have actual
experience on this model.


Newer models, mainly over-engineered surround models, do have more
sophisticated protection and diagnostic features, but that's not even what
you were _trying_ to talk about.
I'd like to point out again that this is a lower-end, older receiver, around
1980 vintage or so.


Mark Z.