Yamaha RV-X450
 

The amp won't come out of standby unless the power cord is unplugged
for about 20 seconds.

Once you do this it will come on and perform ok.

It can be turned on and off with no problem and will stay running
indefinitely

When turned off for about 5 mins then won't come out of standby again.

I have just got a copy of the service manual looks like it may be the
power good signal.

Anyone seen this before?

Yamaha RV-X450
 

Check for electrolytic capacitors, especially in the power supply that are
out of specs. You would be best off to use an ESR meter to find these. Once
the bad ones are found, you can replace them.

--

JANA
_____


"jw51" wrote in message
...
The amp won't come out of standby unless the power cord is unplugged
for about 20 seconds.

Once you do this it will come on and perform ok.

It can be turned on and off with no problem and will stay running
indefinitely

When turned off for about 5 mins then won't come out of standby again.

I have just got a copy of the service manual looks like it may be the
power good signal.

Anyone seen this before?

Yamaha RV-X450
 

jw51 wrote in message
...
The amp won't come out of standby unless the power cord is unplugged
for about 20 seconds.

Once you do this it will come on and perform ok.

It can be turned on and off with no problem and will stay running
indefinitely

When turned off for about 5 mins then won't come out of standby again.

I have just got a copy of the service manual looks like it may be the
power good signal.

Anyone seen this before?


Such delayed effects are usually due to chemical effects within electrolytic
capacitors, not necessarily the big ones. Check/monitor voltages over the
ones around the protection circuitry, they may form a battery-like
chemistry, so producing an offset, incorrectly interpreted as wonky power
rails .


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Yamaha RV-X450
 

"jw51" wrote in message
...
The amp won't come out of standby unless the power cord is unplugged
for about 20 seconds.

Once you do this it will come on and perform ok.

It can be turned on and off with no problem and will stay running
indefinitely

When turned off for about 5 mins then won't come out of standby again.

I have just got a copy of the service manual looks like it may be the
power good signal.

Anyone seen this before?


This could be a tough one. The generic replies about capacitors probably
aren't going to help much.

I would look at the reset line for the micro - it could be drifting low and
there have been a few problems involving the reset on these.
The reset comes from the subtrans board, and loops through the Main (2)
board up to the Function (2) board, which if I read the print correctly is
the top "connect" board towards the rear of the unit, easily accessible for
voltage measurements etc.

If the reset is dropping do not assume the fault is on the subtrans board,
it would more likely be getting loaded down, possibly by a lead-free solder
"whisker" issue or the like.


Mark Z.

Yamaha RV-X450
 

On Feb 20, 7:05*pm, "N Cook" wrote:
jw51 wrote in message

...

The amp won't come out of standby unless the power cord is unplugged
for about 20 seconds.

Once you do this it will come on and perform ok.

It can be turned on and off with no problem and will stay running
indefinitely

When turned off for about 5 mins then won't come out of standby again.

I have just got a copy of the service manual looks like it may be the
power good signal.

Anyone seen this before?

Such delayed effects are usually due to chemical effects within electrolytic
capacitors, not necessarily the big ones. Check/monitor voltages over the
ones around the protection circuitry, they may form a battery-like
chemistry, so producing an offset, incorrectly interpreted as wonky power
rails .

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list onhttp://home..graffiti.net/diverse:graffiti.net/

Found the problem the power good signal was low instead of high.
Caused by low current in opto IC401 led, traced to C405 which is in
series with the 240V AC.
Difficult to diagnose as the area is at mains potential and there are
no voltages marked on the diagram.
The part of the circuit that regulates the standby 10 Volts through
opto IC403 was working ok.

Yamaha RV-X450
 

"jw51" wrote in message
...
On Feb 20, 7:05 pm, "N Cook" wrote:
jw51 wrote in message

...

The amp won't come out of standby unless the power cord is unplugged
for about 20 seconds.

Once you do this it will come on and perform ok.

It can be turned on and off with no problem and will stay running
indefinitely

When turned off for about 5 mins then won't come out of standby again.

I have just got a copy of the service manual looks like it may be the
power good signal.

Anyone seen this before?

Such delayed effects are usually due to chemical effects within
electrolytic
capacitors, not necessarily the big ones. Check/monitor voltages over the
ones around the protection circuitry, they may form a battery-like
chemistry, so producing an offset, incorrectly interpreted as wonky power
rails .

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list
onhttp://home.graffiti.net/diverse:graffiti.net/

Found the problem the power good signal was low instead of high.
Caused by low current in opto IC401 led, traced to C405 which is in
series with the 240V AC.
Difficult to diagnose as the area is at mains potential and there are
no voltages marked on the diagram.
The part of the circuit that regulates the standby 10 Volts through
opto IC403 was working ok.


"Power good" was the reset from Q402, yes?

Mark Z.

Yamaha RV-X450
 

Not from Q402 but from Q403 signal named PDET.

Mark D. Zacharias wrote:

"jw51" wrote in message
...
On Feb 20, 7:05 pm, "N Cook" wrote:
jw51 wrote in message

...

The amp won't come out of standby unless the power cord is unplugged
for about 20 seconds.

Once you do this it will come on and perform ok.

It can be turned on and off with no problem and will stay running
indefinitely

When turned off for about 5 mins then won't come out of standby again.

I have just got a copy of the service manual looks like it may be the
power good signal.

Anyone seen this before?

Such delayed effects are usually due to chemical effects within
electrolytic
capacitors, not necessarily the big ones. Check/monitor voltages over the
ones around the protection circuitry, they may form a battery-like
chemistry, so producing an offset, incorrectly interpreted as wonky power
rails .

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list
onhttp://home.graffiti.net/diverse:graffiti.net/

Found the problem the power good signal was low instead of high.
Caused by low current in opto IC401 led, traced to C405 which is in
series with the 240V AC.
Difficult to diagnose as the area is at mains potential and there are
no voltages marked on the diagram.
The part of the circuit that regulates the standby 10 Volts through
opto IC403 was working ok.


"Power good" was the reset from Q402, yes?

Mark Z.

Yamaha RV-X450
 

"jw51" wrote in message
...
Not from Q402 but from Q403 signal named PDET.

Mark D. Zacharias wrote:

"jw51" wrote in message
...
On Feb 20, 7:05 pm, "N Cook" wrote:
jw51 wrote in message

...

The amp won't come out of standby unless the power cord is unplugged
for about 20 seconds.

Once you do this it will come on and perform ok.

It can be turned on and off with no problem and will stay running
indefinitely

When turned off for about 5 mins then won't come out of standby
again.

I have just got a copy of the service manual looks like it may be the
power good signal.

Anyone seen this before?

Such delayed effects are usually due to chemical effects within
electrolytic
capacitors, not necessarily the big ones. Check/monitor voltages over
the
ones around the protection circuitry, they may form a battery-like
chemistry, so producing an offset, incorrectly interpreted as wonky
power
rails .

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list
onhttp://home.graffiti.net/diverse:graffiti.net/

Found the problem the power good signal was low instead of high.
Caused by low current in opto IC401 led, traced to C405 which is in
series with the 240V AC.
Difficult to diagnose as the area is at mains potential and there are
no voltages marked on the diagram.
The part of the circuit that regulates the standby 10 Volts through
opto IC403 was working ok.


"Power good" was the reset from Q402, yes?

Mark Z.


Shoulda seen that. Thanks for the update.

Mark Z.