Our faithful, 20 year-old Yamaha R-50 recently failed to power on.
After checking things like the power cord and outlet, I carefully
removed the cover and found a blown slow-blow fuse close to the the
power transformer. I replaced this 250v 4a fuse and now the receiver
will power up (lights on the console are lit). However, I am still
getting no output to either the speakers or headphones, from either the
radio or aux (CD) sources. Is there anything else that a careful novice
like me can try or check, or is our receiver a lost cause?

Many thanks for any suggestions,
Greg

"Greg" wrote in message
ups.com...
Our faithful, 20 year-old Yamaha R-50 recently failed to power on.
After checking things like the power cord and outlet, I carefully
removed the cover and found a blown slow-blow fuse close to the the
power transformer. I replaced this 250v 4a fuse and now the receiver
will power up (lights on the console are lit). However, I am still
getting no output to either the speakers or headphones, from either the
radio or aux (CD) sources. Is there anything else that a careful novice
like me can try or check, or is our receiver a lost cause?

Many thanks for any suggestions,
Greg

Be careful with Google - since Yamaha also made an R-50 helicopter :-)

I never view equipment as a "lost cause" unless extensive damage has
occurred (e.g. lightning) to a large number of components.

The Yamaha R-50 service manual is available.
http://www.vintageaudiomanuals.com/-XYZ-.htm

My troubleshooting regime starts with the power system. Is it functioning
properly (proper voltages, etc.). Since you replaced the fuse and you are
getting power to some devices (lights) - this would lead to in the following
direction.

BTW all of this work if performed with the receiver unplugged from AC mains
!!

1. Check rectifier (bridge or full wave design). Verify voltages correct
(service manual helpful here).

2. Go to Power amplifier stage. I am not familiar with this model, but for
this era - 2N3055 NPN transistors were not uncommon. Take out of circuit
and test each -- as well as any ballast resistors.

That's a start.

gb

T'hanks very much, gb! I had no idea that Yamaha was so diversified!
Your suggestions are already over my head, but it is reassuring to hear
that "lost cause" may be premature. I'm thinking that my next step will
be to carry your suggestions with me when I take this unit into a
repair shop.


g. beat wrote:
"Greg" wrote in message
ups.com...
Our faithful, 20 year-old Yamaha R-50 recently failed to power on.
After checking things like the power cord and outlet, I carefully
removed the cover and found a blown slow-blow fuse close to the the
power transformer. I replaced this 250v 4a fuse and now the receiver
will power up (lights on the console are lit). However, I am still
getting no output to either the speakers or headphones, from either the
radio or aux (CD) sources. Is there anything else that a careful novice
like me can try or check, or is our receiver a lost cause?

Many thanks for any suggestions,
Greg

Be careful with Google - since Yamaha also made an R-50 helicopter :-)

I never view equipment as a "lost cause" unless extensive damage has
occurred (e.g. lightning) to a large number of components.

The Yamaha R-50 service manual is available.
http://www.vintageaudiomanuals.com/-XYZ-.htm

My troubleshooting regime starts with the power system. Is it functioning
properly (proper voltages, etc.). Since you replaced the fuse and you are
getting power to some devices (lights) - this would lead to in the following
direction.

BTW all of this work if performed with the receiver unplugged from AC mains
!!

1. Check rectifier (bridge or full wave design). Verify voltages correct
(service manual helpful here).

2. Go to Power amplifier stage. I am not familiar with this model, but for
this era - 2N3055 NPN transistors were not uncommon. Take out of circuit
and test each -- as well as any ballast resistors.

That's a start.

gb

Greg wrote:
Our faithful, 20 year-old Yamaha R-50 recently failed to power on.
After checking things like the power cord and outlet, I carefully
removed the cover and found a blown slow-blow fuse close to the the
power transformer. I replaced this 250v 4a fuse and now the receiver
will power up (lights on the console are lit). However, I am still
getting no output to either the speakers or headphones, from either
the radio or aux (CD) sources. Is there anything else that a careful
novice like me can try or check, or is our receiver a lost cause?

Many thanks for any suggestions,
Greg

The R-50 used an output IC which is no longer available from Yamaha or
generic parts distributors. I forget the STK or IG number on the chip. If
there's a DC output on one channel and the protect circuit is not firing the
relay, you're probably out of luck on this one.

Mark Z.

"Mark D. Zacharias" wrote in message
. com...
Greg wrote:
Our faithful, 20 year-old Yamaha R-50 recently failed to power on.
After checking things like the power cord and outlet, I carefully
removed the cover and found a blown slow-blow fuse close to the the
power transformer. I replaced this 250v 4a fuse and now the receiver
will power up (lights on the console are lit). However, I am still
getting no output to either the speakers or headphones, from either
the radio or aux (CD) sources. Is there anything else that a careful
novice like me can try or check, or is our receiver a lost cause?

Many thanks for any suggestions,
Greg

The R-50 used an output IC which is no longer available from Yamaha or
generic parts distributors. I forget the STK or IG number on the chip. If
there's a DC output on one channel and the protect circuit is not firing
the relay, you're probably out of luck on this one.

Mark Z.
Mark -

thanks for that - since I did not have a schematic. Loss of the IC is one
possible scenario - but not the only one - you really don't know --- no one
knows until actual diagnose. (can't start behaving like the medical
doctors - "He's dead - Jim"!)

gb

"g. beat " @spam protected wrote in message
...

thanks for that - since I did not have a schematic. Loss of the IC is one
possible scenario - but not the only one - you really don't know --- no
one
knows until actual diagnose. (can't start behaving like the medical
doctors - "He's dead - Jim"!)

gb


Well since you have a schematic now, I would grab my multimeter and start
checking output voltages of the tranformer(s). Some have multiple windings,
you may be getting 28v for panel lights etc. but no power to any of the
other circuits.

"Michael Ware" wrote in message
...

"g. beat " @spam protected wrote in message
...

thanks for that - since I did not have a schematic. Loss of the IC is
one
possible scenario - but not the only one - you really don't know --- no
one
knows until actual diagnose. (can't start behaving like the medical
doctors - "He's dead - Jim"!)

gb


Well since you have a schematic now, I would grab my multimeter and start
checking output voltages of the tranformer(s). Some have multiple
windings,
you may be getting 28v for panel lights etc. but no power to any of the
other circuits.



When the (no longer available) output IC is confirmed bad, I'll expect
acknowledgement. I've worked on enough of these to know, and that's my
prediction.


Mark Z.

"Mark D. Zacharias" wrote in message
news

"Michael Ware" wrote in message
...

"g. beat " @spam protected wrote in message
...

thanks for that - since I did not have a schematic. Loss of the IC is
one
possible scenario - but not the only one - you really don't know --- no
one
knows until actual diagnose. (can't start behaving like the medical
doctors - "He's dead - Jim"!)

gb


Well since you have a schematic now, I would grab my multimeter and start
checking output voltages of the tranformer(s). Some have multiple
windings,
you may be getting 28v for panel lights etc. but no power to any of the
other circuits.



When the (no longer available) output IC is confirmed bad, I'll expect
acknowledgement. I've worked on enough of these to know, and that's my
prediction.


Mark Z.

Ditto that.

I don't recall if this one had multiple windings at all, but I can't recall
ever having a transformer fail in one of these. Nearly every one was output
ICs. Been a while since we have seen any.

Besides, those old recivers with the single and two digit R- numbers, and
basically anything that used integrated outputs were some of the worst stuff
that Yamaha ever made. Not bad and even reasonably reliable if not pushed
hard or into a low impedance load, but they were never up to par with the
early units nor the stuff that followed. No reason to get teary-eyed about
retiring this one.

Leonard

"Mark D. Zacharias" writes:

"Michael Ware" wrote in message
...

"g. beat " @spam protected wrote in message
...

thanks for that - since I did not have a schematic. Loss of the IC is
one
possible scenario - but not the only one - you really don't know --- no
one
knows until actual diagnose. (can't start behaving like the medical
doctors - "He's dead - Jim"!)

gb


Well since you have a schematic now, I would grab my multimeter and start
checking output voltages of the tranformer(s). Some have multiple
windings,
you may be getting 28v for panel lights etc. but no power to any of the
other circuits.

When the (no longer available) output IC is confirmed bad, I'll expect
acknowledgement. I've worked on enough of these to know, and that's my
prediction.

I'm sure you will get all the accolades you can handle.

But, suppose he does find it to be bad? Is it so specialized that
something can't be subbed with some modification?

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

Sam Goldwasser wrote:
"Mark D. Zacharias" writes:

"Michael Ware" wrote in message
...

"g. beat " @spam protected wrote in message
...

thanks for that - since I did not have a schematic. Loss of the
IC is one
possible scenario - but not the only one - you really don't know
--- no one knows until actual diagnose. (can't start behaving
like the medical doctors - "He's dead - Jim"!)

gb


Well since you have a schematic now, I would grab my multimeter and
start checking output voltages of the tranformer(s). Some have
multiple windings,
you may be getting 28v for panel lights etc. but no power to any of
the other circuits.

When the (no longer available) output IC is confirmed bad, I'll
expect acknowledgement. I've worked on enough of these to know, and
that's my prediction.

I'm sure you will get all the accolades you can handle.

But, suppose he does find it to be bad? Is it so specialized that
something can't be subbed with some modification?

--- sam | Sci.Electronics.Repair FAQ:

A lot of effort for not much receiver....and it would require all the
documentation on the original chip, proposed subs, also engineering notes if
circuit capacitors or other components needed to be added or deleted. Then
of course there are mechanical mounting considerations.

Mark Z.

"Mark D. Zacharias" writes:

Sam Goldwasser wrote:
"Mark D. Zacharias" writes:

"Michael Ware" wrote in message
...

"g. beat " @spam protected wrote in message
...

thanks for that - since I did not have a schematic. Loss of the
IC is one
possible scenario - but not the only one - you really don't know
--- no one knows until actual diagnose. (can't start behaving
like the medical doctors - "He's dead - Jim"!)

gb


Well since you have a schematic now, I would grab my multimeter and
start checking output voltages of the tranformer(s). Some have
multiple windings,
you may be getting 28v for panel lights etc. but no power to any of
the other circuits.

When the (no longer available) output IC is confirmed bad, I'll
expect acknowledgement. I've worked on enough of these to know, and
that's my prediction.

I'm sure you will get all the accolades you can handle.

But, suppose he does find it to be bad? Is it so specialized that
something can't be subbed with some modification?

--- sam | Sci.Electronics.Repair FAQ:

A lot of effort for not much receiver....and it would require all the
documentation on the original chip, proposed subs, also engineering notes if
circuit capacitors or other components needed to be added or deleted. Then
of course there are mechanical mounting considerations.

Mark Z.

So he should save the knobs and heatsink, and give the remains a nice
burial.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

Yipes! I turned away from this thread for a couple days and now see
that it's grabbed your interest! Many thanks for all for your
suggestions. Everything you have suggested (except for the nice burial)
is well beyond my capabilities. I'm just resisting the patriotic
tendency to treat this receiver like a disposable consumer good. I'll
carry your suggestions with me to a repair shop and hope for the best.
Again, thanks to all for your assistance!

Greg


Sam Goldwasser wrote:
"Mark D. Zacharias" writes:

Sam Goldwasser wrote:
"Mark D. Zacharias" writes:

"Michael Ware" wrote in message
...

"g. beat " @spam protected wrote in message
...

thanks for that - since I did not have a schematic. Loss of the
IC is one
possible scenario - but not the only one - you really don't know
--- no one knows until actual diagnose. (can't start behaving
like the medical doctors - "He's dead - Jim"!)

gb


Well since you have a schematic now, I would grab my multimeter and
start checking output voltages of the tranformer(s). Some have
multiple windings,
you may be getting 28v for panel lights etc. but no power to any of
the other circuits.

When the (no longer available) output IC is confirmed bad, I'll
expect acknowledgement. I've worked on enough of these to know, and
that's my prediction.

I'm sure you will get all the accolades you can handle.

But, suppose he does find it to be bad? Is it so specialized that
something can't be subbed with some modification?

--- sam | Sci.Electronics.Repair FAQ:

A lot of effort for not much receiver....and it would require all the
documentation on the original chip, proposed subs, also engineering notes if
circuit capacitors or other components needed to be added or deleted. Then
of course there are mechanical mounting considerations.

Mark Z.

So he should save the knobs and heatsink, and give the remains a nice
burial.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

Mark D. Zacharias wrote:
Sam Goldwasser wrote:
"Mark D. Zacharias" writes:

"Michael Ware" wrote in message
...
"g. beat " @spam protected wrote in message
...
thanks for that - since I did not have a schematic. Loss of the
IC is one
possible scenario - but not the only one - you really don't know
--- no one knows until actual diagnose. (can't start behaving
like the medical doctors - "He's dead - Jim"!)

gb


Well since you have a schematic now, I would grab my multimeter and
start checking output voltages of the tranformer(s). Some have
multiple windings,
you may be getting 28v for panel lights etc. but no power to any of
the other circuits.
When the (no longer available) output IC is confirmed bad, I'll
expect acknowledgement. I've worked on enough of these to know, and
that's my prediction.
I'm sure you will get all the accolades you can handle.

But, suppose he does find it to be bad? Is it so specialized that
something can't be subbed with some modification?

--- sam | Sci.Electronics.Repair FAQ:

A lot of effort for not much receiver....and it would require all the
documentation on the original chip, proposed subs, also engineering notes if
circuit capacitors or other components needed to be added or deleted. Then
of course there are mechanical mounting considerations.

Still, if he was so inclined, really all he's looking for is signal
in/out and B+/-. Then it's a matter of scabbing a chip amp onto the
heat sync along with a small pc board containing its associated components.

Not original, but....

jak

Mark Z.

Greg wrote:

Our faithful, 20 year-old Yamaha R-50 recently failed to power on.
After checking things like the power cord and outlet, I carefully
removed the cover and found a blown slow-blow fuse close to the the
power transformer. I replaced this 250v 4a fuse and now the receiver
will power up (lights on the console are lit). However, I am still
getting no output to either the speakers or headphones, from either the
radio or aux (CD) sources. Is there anything else that a careful novice
like me can try or check, or is our receiver a lost cause?

Many thanks for any suggestions,
Greg

you most likely have bad Caps in the power supply..
a lot of receivers have power supplies that
sample the voltage at the main caps while they
are being charged via a resistor to allow for slow
start up to avoid inrush currents.
when the desired charge is reached, a relay will
bridge this trickle charging system to allow full power
and also start the receiver.
since your fuse was blown, it's possible (theory only) that
one of your caps or even a bridge rectifier has shorted and
is not allowing for the voltage to reach its peak, which btw
must be the reason why you didn't blow out the new fuse you put in ?
if this is the case, you should have a high wattage resistor getting
vary hot!, or maybe by this time has opened or unsoldered it self from
the board ?



--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

Jamie wrote:
snip

you most likely have bad Caps in the power supply..
a lot of receivers have power supplies that
sample the voltage at the main caps while they
are being charged via a resistor to allow for slow
start up to avoid inrush currents.
when the desired charge is reached, a relay will
bridge this trickle charging system to allow full power
and also start the receiver.
since your fuse was blown, it's possible (theory only) that
one of your caps or even a bridge rectifier has shorted and
is not allowing for the voltage to reach its peak, which btw
must be the reason why you didn't blow out the new fuse you put in ?
if this is the case, you should have a high wattage resistor getting
vary hot!, or maybe by this time has opened or unsoldered it self from
the board ?

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.

There is only a small chance that the OP's receiver can be repaired at all,
since the main output IC is no longer available, and is VERY likely the
fault. The only definitive way to know for certain is to troubleshoot with a
service manual and a knowledgeable technique. Since the OP has neither of
these, money spent getting a repair estimate is a low-percentage proposition
(free estimates are a thing of the past). Add to this the fact that it
wasn't one of Yamaha's best to start with, and there is near-unanimity on
the group, including the OP, that the receiver should just be replaced
instead. New and high-quality vintage gear abound.

Mark Z.

"Jamie" t wrote in message
...
Greg wrote:

Our faithful, 20 year-old Yamaha R-50 recently failed to power on.
After checking things like the power cord and outlet, I carefully
removed the cover and found a blown slow-blow fuse close to the the
power transformer. I replaced this 250v 4a fuse and now the receiver
will power up (lights on the console are lit). However, I am still
getting no output to either the speakers or headphones, from either the
radio or aux (CD) sources. Is there anything else that a careful novice
like me can try or check, or is our receiver a lost cause?

Many thanks for any suggestions,
Greg

you most likely have bad Caps in the power supply..
a lot of receivers have power supplies that
sample the voltage at the main caps while they
are being charged via a resistor to allow for slow
start up to avoid inrush currents.
when the desired charge is reached, a relay will
bridge this trickle charging system to allow full power
and also start the receiver.
since your fuse was blown, it's possible (theory only) that
one of your caps or even a bridge rectifier has shorted and
is not allowing for the voltage to reach its peak, which btw
must be the reason why you didn't blow out the new fuse you put in ?
if this is the case, you should have a high wattage resistor getting
vary hot!, or maybe by this time has opened or unsoldered it self from
the board ?

Have you ever worked on one of these? Trying to help is a good thing, but
posting speculation when you have no idea about the design and typical
failures in the specific unit is less than helpful. Sounds like you have no
idea what you are talking about or you did not pay attention to the post.
If the bridge was blown he would have never get it to do anything but blow
more fuses immediately.

The only thing typical in these units in the power supply might be some
dried up glue around the caps that eats up leads on parts and jumpers when
it absorbs moisture from the air. The OP has already received good advice
not to waste any resources on this one from people who have extensive
experience with them. Don't send him chasing his tail.

Leonard

"Jamie" t wrote in message
...
oh please, can't you do better than that ?

No need to. Mark already did. Too bad I missed his post before I
responded. It was much more precise than mine...half-baked
goobledygook...LOL. As usual, he nailed it.

Leonard

Mark D. Zacharias wrote:

Jamie wrote:
snip

you most likely have bad Caps in the power supply..
a lot of receivers have power supplies that
sample the voltage at the main caps while they
are being charged via a resistor to allow for slow
start up to avoid inrush currents.
when the desired charge is reached, a relay will
bridge this trickle charging system to allow full power
and also start the receiver.
since your fuse was blown, it's possible (theory only) that
one of your caps or even a bridge rectifier has shorted and
is not allowing for the voltage to reach its peak, which btw
must be the reason why you didn't blow out the new fuse you put in ?
if this is the case, you should have a high wattage resistor getting
vary hot!, or maybe by this time has opened or unsoldered it self from
the board ?


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.




--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

Leonard Caillouet wrote:

"Jamie" t wrote in message
...

Greg wrote:


Our faithful, 20 year-old Yamaha R-50 recently failed to power on.
After checking things like the power cord and outlet, I carefully
removed the cover and found a blown slow-blow fuse close to the the
power transformer. I replaced this 250v 4a fuse and now the receiver
will power up (lights on the console are lit). However, I am still
getting no output to either the speakers or headphones, from either the
radio or aux (CD) sources. Is there anything else that a careful novice
like me can try or check, or is our receiver a lost cause?

Many thanks for any suggestions,
Greg


you most likely have bad Caps in the power supply..
a lot of receivers have power supplies that
sample the voltage at the main caps while they
are being charged via a resistor to allow for slow
start up to avoid inrush currents.
when the desired charge is reached, a relay will
bridge this trickle charging system to allow full power
and also start the receiver.
since your fuse was blown, it's possible (theory only) that
one of your caps or even a bridge rectifier has shorted and
is not allowing for the voltage to reach its peak, which btw
must be the reason why you didn't blow out the new fuse you put in ?
if this is the case, you should have a high wattage resistor getting
vary hot!, or maybe by this time has opened or unsoldered it self from
the board ?


Have you ever worked on one of these? Trying to help is a good thing, but
posting speculation when you have no idea about the design and typical
failures in the specific unit is less than helpful. Sounds like you have no
idea what you are talking about or you did not pay attention to the post.
If the bridge was blown he would have never get it to do anything but blow
more fuses immediately.

The only thing typical in these units in the power supply might be some
dried up glue around the caps that eats up leads on parts and jumpers when
it absorbs moisture from the air. The OP has already received good advice
not to waste any resources on this one from people who have extensive
experience with them. Don't send him chasing his tail.

Leonard


oh please, can't you do better than that ?


--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

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.

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.

"Greg" wrote in message
oups.com...
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

Hope you are happy with your new purchase. We were trying to give you the
best advice that we could. I guess Mark and I both get a bit torqued with
some of the BS that people post. It is hard enough for people to know what
to make of the various advice that they get on usenet, but when guys with
specific experience with the units give specific advice and others post
generic info that may or may not be relevant, it makes it seem like a waste
of time to try to help people. Then when someone posts something that is
just plain inaccurate, it is likely to raise a flag.

Be well. Be in touch.

Leonard

Leonard Caillouet wrote:
"Greg" wrote in message
oups.com...
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

Hope you are happy with your new purchase. We were trying to give
you the best advice that we could. I guess Mark and I both get a bit
torqued with some of the BS that people post. It is hard enough for
people to know what to make of the various advice that they get on
usenet, but when guys with specific experience with the units give
specific advice and others post generic info that may or may not be
relevant, it makes it seem like a waste of time to try to help
people. Then when someone posts something that is just plain
inaccurate, it is likely to raise a flag.
Be well. Be in touch.

Leonard


What he said.


mz

Leonard Caillouet wrote:
"Greg" wrote in message
oups.com...
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

Hope you are happy with your new purchase. We were trying to give
you the best advice that we could. I guess Mark and I both get a bit
torqued with some of the BS that people post. It is hard enough for
people to know what to make of the various advice that they get on
usenet, but when guys with specific experience with the units give
specific advice and others post generic info that may or may not be
relevant, it makes it seem like a waste of time to try to help
people. Then when someone posts something that is just plain
inaccurate, it is likely to raise a flag.
Be well. Be in touch.

Leonard


Man, if he thought we were rough he really is a newbie around here! This was
one of the more polite threads of it's sort I've seen in a while!

Mark Z.