Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Yamaha Stagepas 300 failure mode

Just as well I'm not paying Yamaha 50 squid a pop for these blown amps.
Repaired one end of 2011 , it bounced back.
It is due to the short stub lead between amp and its immediate speaker, the
elbow connectors.
No name elbows on lead marked UPOFC Classic Pro Loudspeaker Cable. Took a
bit of grinding to cut the top off the elbow, quite thick monkey metal. The
ground connection out to the cable solder point is like a solder tag but
with a 2mm x 1mm x tag thickness lug opposite the solder extension ,that
locates into the moulded plastic insulator. The tag is not spot
welded/bolted to the elbow metal so any twisting of the cable is transfered
to the tag and the ring part can twist and touch the conductor stem to the
tip, as the cylinder insulation along this stem does not extend into this
solder tag, or perhaps as only touching ground contact, then localised
heating and the cylinder insulation melting back a bit. I've not explored
that far in, the top moulded insulation plastic does not look melted.
These elbows have a vague brassy/coppery tinge of plating or something just
on the tips , the main elbow body is Hex in plan and between it and the stem
is what looks like a hank bush swage-form.



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Default Yamaha Stagepas 300 failure mode

On 31/01/2012 11:05, N_Cook wrote:
Just as well I'm not paying Yamaha 50 squid a pop for these blown amps.
Repaired one end of 2011 , it bounced back.
It is due to the short stub lead between amp and its immediate speaker, the
elbow connectors.
No name elbows on lead marked UPOFC Classic Pro Loudspeaker Cable. Took a
bit of grinding to cut the top off the elbow, quite thick monkey metal. The
ground connection out to the cable solder point is like a solder tag but
with a 2mm x 1mm x tag thickness lug opposite the solder extension ,that
locates into the moulded plastic insulator. The tag is not spot
welded/bolted to the elbow metal so any twisting of the cable is transfered
to the tag and the ring part can twist and touch the conductor stem to the
tip, as the cylinder insulation along this stem does not extend into this
solder tag, or perhaps as only touching ground contact, then localised
heating and the cylinder insulation melting back a bit. I've not explored
that far in, the top moulded insulation plastic does not look melted.
These elbows have a vague brassy/coppery tinge of plating or something just
on the tips , the main elbow body is Hex in plan and between it and the stem
is what looks like a hank bush swage-form.



Several people have reported that their problems began when they started
using speaker cables other than those supplied with the units which
sadly are just not quite long enough.

Ron
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Default Yamaha Stagepas 300 failure mode


"Ron" wrote in message
...
On 31/01/2012 11:05, N_Cook wrote:
Just as well I'm not paying Yamaha 50 squid a pop for these blown amps.
Repaired one end of 2011 , it bounced back.
It is due to the short stub lead between amp and its immediate speaker,
the
elbow connectors.
No name elbows on lead marked UPOFC Classic Pro Loudspeaker Cable. Took a
bit of grinding to cut the top off the elbow, quite thick monkey metal.
The
ground connection out to the cable solder point is like a solder tag but
with a 2mm x 1mm x tag thickness lug opposite the solder extension ,that
locates into the moulded plastic insulator. The tag is not spot
welded/bolted to the elbow metal so any twisting of the cable is
transfered
to the tag and the ring part can twist and touch the conductor stem to
the
tip, as the cylinder insulation along this stem does not extend into this
solder tag, or perhaps as only touching ground contact, then localised
heating and the cylinder insulation melting back a bit. I've not explored
that far in, the top moulded insulation plastic does not look melted.
These elbows have a vague brassy/coppery tinge of plating or something
just
on the tips , the main elbow body is Hex in plan and between it and the
stem
is what looks like a hank bush swage-form.



Several people have reported that their problems began when they started
using speaker cables other than those supplied with the units which sadly
are just not quite long enough.

Ron



The thing is, Yamahas user manual specifically warns against using speaker
cables other than those supplied with the units, so they are covered.

e.g.

11 Only use attachments/accessories specified by the manufacturer.

and:

To avoid any possible malfunction, use only the speaker cables included with
the device




Cheers,


Gareth.


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Default Yamaha Stagepas 300 failure mode

Gareth Magennis wrote in message
...

"Ron" wrote in message
...
On 31/01/2012 11:05, N_Cook wrote:
Just as well I'm not paying Yamaha 50 squid a pop for these blown amps.
Repaired one end of 2011 , it bounced back.
It is due to the short stub lead between amp and its immediate speaker,
the
elbow connectors.
No name elbows on lead marked UPOFC Classic Pro Loudspeaker Cable. Took

a
bit of grinding to cut the top off the elbow, quite thick monkey metal.
The
ground connection out to the cable solder point is like a solder tag

but
with a 2mm x 1mm x tag thickness lug opposite the solder extension

,that
locates into the moulded plastic insulator. The tag is not spot
welded/bolted to the elbow metal so any twisting of the cable is
transfered
to the tag and the ring part can twist and touch the conductor stem to
the
tip, as the cylinder insulation along this stem does not extend into

this
solder tag, or perhaps as only touching ground contact, then localised
heating and the cylinder insulation melting back a bit. I've not

explored
that far in, the top moulded insulation plastic does not look melted.
These elbows have a vague brassy/coppery tinge of plating or something
just
on the tips , the main elbow body is Hex in plan and between it and the
stem
is what looks like a hank bush swage-form.



Several people have reported that their problems began when they started
using speaker cables other than those supplied with the units which

sadly
are just not quite long enough.

Ron



The thing is, Yamahas user manual specifically warns against using speaker
cables other than those supplied with the units, so they are covered.

e.g.

11 Only use attachments/accessories specified by the manufacturer.

and:

To avoid any possible malfunction, use only the speaker cables included

with
the device




Cheers,


Gareth.



The owner dropped in the outlier speaker and long cable and specifically
said it came with the amp, new. That has the cable sheathing pulling out of
the strain relief mouldings to both of the jacks. I'm waiting on the owner
getting back to me about the origins of the short lead


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Default Yamaha Stagepas 300 failure mode

Another identifier , perhaps, for these shoddy elbow jacks, the "hank shank"
section has 32 "teeth" around it




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Default Yamaha Stagepas 300 failure mode

Gareth Magennis wrote in message
...

"Ron" wrote in message
...
On 31/01/2012 11:05, N_Cook wrote:
Just as well I'm not paying Yamaha 50 squid a pop for these blown amps.
Repaired one end of 2011 , it bounced back.
It is due to the short stub lead between amp and its immediate speaker,
the
elbow connectors.
No name elbows on lead marked UPOFC Classic Pro Loudspeaker Cable. Took

a
bit of grinding to cut the top off the elbow, quite thick monkey metal.
The
ground connection out to the cable solder point is like a solder tag

but
with a 2mm x 1mm x tag thickness lug opposite the solder extension

,that
locates into the moulded plastic insulator. The tag is not spot
welded/bolted to the elbow metal so any twisting of the cable is
transfered
to the tag and the ring part can twist and touch the conductor stem to
the
tip, as the cylinder insulation along this stem does not extend into

this
solder tag, or perhaps as only touching ground contact, then localised
heating and the cylinder insulation melting back a bit. I've not

explored
that far in, the top moulded insulation plastic does not look melted.
These elbows have a vague brassy/coppery tinge of plating or something
just
on the tips , the main elbow body is Hex in plan and between it and the
stem
is what looks like a hank bush swage-form.



Several people have reported that their problems began when they started
using speaker cables other than those supplied with the units which

sadly
are just not quite long enough.

Ron



The thing is, Yamahas user manual specifically warns against using speaker
cables other than those supplied with the units, so they are covered.

e.g.

11 Only use attachments/accessories specified by the manufacturer.

and:

To avoid any possible malfunction, use only the speaker cables included

with
the device




Cheers,


Gareth.




The foot long lead is not original Yamaha. The general warning applies about
these non-moulded , ie user applicable solder-on tags with screw-on knurled
barrel over the cable entry. The soldering and choice of cable was fine, it
is a bad design of connector


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Default Yamaha Stagepas 300 failure mode


"N_Cook" wrote in message
...
Gareth Magennis wrote in message
...

"Ron" wrote in message
...
On 31/01/2012 11:05, N_Cook wrote:
Just as well I'm not paying Yamaha 50 squid a pop for these blown
amps.
Repaired one end of 2011 , it bounced back.
It is due to the short stub lead between amp and its immediate
speaker,
the
elbow connectors.
No name elbows on lead marked UPOFC Classic Pro Loudspeaker Cable.
Took

a
bit of grinding to cut the top off the elbow, quite thick monkey
metal.
The
ground connection out to the cable solder point is like a solder tag

but
with a 2mm x 1mm x tag thickness lug opposite the solder extension

,that
locates into the moulded plastic insulator. The tag is not spot
welded/bolted to the elbow metal so any twisting of the cable is
transfered
to the tag and the ring part can twist and touch the conductor stem to
the
tip, as the cylinder insulation along this stem does not extend into

this
solder tag, or perhaps as only touching ground contact, then localised
heating and the cylinder insulation melting back a bit. I've not

explored
that far in, the top moulded insulation plastic does not look melted.
These elbows have a vague brassy/coppery tinge of plating or something
just
on the tips , the main elbow body is Hex in plan and between it and
the
stem
is what looks like a hank bush swage-form.



Several people have reported that their problems began when they
started
using speaker cables other than those supplied with the units which

sadly
are just not quite long enough.

Ron



The thing is, Yamahas user manual specifically warns against using
speaker
cables other than those supplied with the units, so they are covered.

e.g.

11 Only use attachments/accessories specified by the manufacturer.

and:

To avoid any possible malfunction, use only the speaker cables included

with
the device




Cheers,


Gareth.




The foot long lead is not original Yamaha. The general warning applies
about
these non-moulded , ie user applicable solder-on tags with screw-on
knurled
barrel over the cable entry. The soldering and choice of cable was fine,
it
is a bad design of connector





So not really a Yamaha Stagepass 300 failure mode as the thread title states
then.



Cheers,


Gareth.


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Default Yamaha Stagepas 300 failure mode

Gareth Magennis wrote in message
...

"N_Cook" wrote in message
...
Gareth Magennis wrote in message
...

"Ron" wrote in message
...
On 31/01/2012 11:05, N_Cook wrote:
Just as well I'm not paying Yamaha 50 squid a pop for these blown
amps.
Repaired one end of 2011 , it bounced back.
It is due to the short stub lead between amp and its immediate
speaker,
the
elbow connectors.
No name elbows on lead marked UPOFC Classic Pro Loudspeaker Cable.
Took

a
bit of grinding to cut the top off the elbow, quite thick monkey
metal.
The
ground connection out to the cable solder point is like a solder tag

but
with a 2mm x 1mm x tag thickness lug opposite the solder extension

,that
locates into the moulded plastic insulator. The tag is not spot
welded/bolted to the elbow metal so any twisting of the cable is
transfered
to the tag and the ring part can twist and touch the conductor stem

to
the
tip, as the cylinder insulation along this stem does not extend into

this
solder tag, or perhaps as only touching ground contact, then

localised
heating and the cylinder insulation melting back a bit. I've not

explored
that far in, the top moulded insulation plastic does not look

melted.
These elbows have a vague brassy/coppery tinge of plating or

something
just
on the tips , the main elbow body is Hex in plan and between it and
the
stem
is what looks like a hank bush swage-form.



Several people have reported that their problems began when they
started
using speaker cables other than those supplied with the units which

sadly
are just not quite long enough.

Ron


The thing is, Yamahas user manual specifically warns against using
speaker
cables other than those supplied with the units, so they are covered.

e.g.

11 Only use attachments/accessories specified by the manufacturer.

and:

To avoid any possible malfunction, use only the speaker cables included

with
the device




Cheers,


Gareth.




The foot long lead is not original Yamaha. The general warning applies
about
these non-moulded , ie user applicable solder-on tags with screw-on
knurled
barrel over the cable entry. The soldering and choice of cable was fine,
it
is a bad design of connector





So not really a Yamaha Stagepass 300 failure mode as the thread title

states
then.



Cheers,


Gareth.




It seems its a fault of Yamaha supplying 2 "long" leads only. Or this owner
from new received only 2 "long" leads and no foot long lead. He got a shop
to make up a foot long lead, and a long-long lead, nothing wrong with the
job they did, unknowingly bad choice of elbows .
Both long leads are not long enough for normal purposes if used as amp and 2
separated speakers. Does Y expect people to coil up the long lead and drape
it around the "powered speaker" unit clamp or something?
This Stagepas is only used as a "powered speaker" and an outlier speaker
with a longer lead than Y supplied.

If Y supplied 3 appropriate leads all with moulded-on connectors then these
faults (including the other pitfall of metal elbows and the grounded handle
and the antiphase "left" channel o/p) would not emerge


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Default Yamaha Stagepas 300 failure mode


It seems its a fault of Yamaha supplying 2 "long" leads only. Or this
owner
from new received only 2 "long" leads and no foot long lead. He got a shop
to make up a foot long lead, and a long-long lead, nothing wrong with the
job they did, unknowingly bad choice of elbows .




Well it sounds to me that the "shop" actually made a BAD and ignorant choice
in the components they used, which ultimately cost the customer a lot of
money.

Doesn't sound like a good job to me at all. Particularly as they no doubt
charged him for the priveledge.



Cheers,



Gareth.







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Default Yamaha Stagepas 300 failure mode

Gareth Magennis wrote in message
...

It seems its a fault of Yamaha supplying 2 "long" leads only. Or this
owner
from new received only 2 "long" leads and no foot long lead. He got a

shop
to make up a foot long lead, and a long-long lead, nothing wrong with

the
job they did, unknowingly bad choice of elbows .




Well it sounds to me that the "shop" actually made a BAD and ignorant

choice
in the components they used, which ultimately cost the customer a lot of
money.

Doesn't sound like a good job to me at all. Particularly as they no doubt
charged him for the priveledge.



Cheers,



Gareth.









with seventh sense of hindsight




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"N_Cook" wrote in message
...
Gareth Magennis wrote in message
...

It seems its a fault of Yamaha supplying 2 "long" leads only. Or this
owner
from new received only 2 "long" leads and no foot long lead. He got a

shop
to make up a foot long lead, and a long-long lead, nothing wrong with

the
job they did, unknowingly bad choice of elbows .




Well it sounds to me that the "shop" actually made a BAD and ignorant

choice
in the components they used, which ultimately cost the customer a lot of
money.

Doesn't sound like a good job to me at all. Particularly as they no
doubt
charged him for the priveledge.



Cheers,



Gareth.





with seventh sense of hindsight





I would have to disagree.
I have done a lot of professional wiring in my time, and if you absolutely
HAVE to use jacks for a speaker connection (a terrible choice for all sorts
of reasons) then you make sure the two connectors cannot ever touch each
other, either by using a proper jack plug (Neutrik) or by sleeving the
soldered terminals in such a way that they will always insulate against the
kind of problems you describe.

The shop it seems chose a crap jack plug and did not sleeve it, and charged
the customer for this terrible piece of work, which cost him a lot of money.


I wouldn't be best pleased.



Cheers,


Gareth.

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Gareth Magennis wrote in message
...


"N_Cook" wrote in message
...
Gareth Magennis wrote in message
...

It seems its a fault of Yamaha supplying 2 "long" leads only. Or this
owner
from new received only 2 "long" leads and no foot long lead. He got a

shop
to make up a foot long lead, and a long-long lead, nothing wrong with

the
job they did, unknowingly bad choice of elbows .



Well it sounds to me that the "shop" actually made a BAD and ignorant

choice
in the components they used, which ultimately cost the customer a lot

of
money.

Doesn't sound like a good job to me at all. Particularly as they no
doubt
charged him for the priveledge.



Cheers,



Gareth.





with seventh sense of hindsight





I would have to disagree.
I have done a lot of professional wiring in my time, and if you absolutely
HAVE to use jacks for a speaker connection (a terrible choice for all

sorts
of reasons) then you make sure the two connectors cannot ever touch each
other, either by using a proper jack plug (Neutrik) or by sleeving the
soldered terminals in such a way that they will always insulate against

the
kind of problems you describe.

The shop it seems chose a crap jack plug and did not sleeve it, and

charged
the customer for this terrible piece of work, which cost him a lot of

money.


I wouldn't be best pleased.



Cheers,


Gareth.


The first time this amp turned up with a blown amp modulle, that was
probably due to non sleeved connector for the "L" channel, I agree there. I
sleeved the elbow and added spiral wrap to the handle to avoid that
happening again. The next time would be due to bad design of elbow, internal
shorting. These look robust jacks from the outside. More robust than those
usual right angle jacks on 100 or 150W combos , very low profile ones. They
can hardly handle 100W from the number of times I've noticed them warming
from compression of the insulation under the rivet-type central connector ,
if not so loose it is intermittant contact.
Any other makes other than Neutrik proven reliable for 150W upwards?


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Default Yamaha Stagepas 300 failure mode


"N_Cook" wrote in message
...
Gareth Magennis wrote in message
...


"N_Cook" wrote in message
...
Gareth Magennis wrote in message
...

It seems its a fault of Yamaha supplying 2 "long" leads only. Or
this
owner
from new received only 2 "long" leads and no foot long lead. He got
a
shop
to make up a foot long lead, and a long-long lead, nothing wrong
with
the
job they did, unknowingly bad choice of elbows .



Well it sounds to me that the "shop" actually made a BAD and ignorant
choice
in the components they used, which ultimately cost the customer a lot

of
money.

Doesn't sound like a good job to me at all. Particularly as they no
doubt
charged him for the priveledge.



Cheers,



Gareth.





with seventh sense of hindsight





I would have to disagree.
I have done a lot of professional wiring in my time, and if you
absolutely
HAVE to use jacks for a speaker connection (a terrible choice for all

sorts
of reasons) then you make sure the two connectors cannot ever touch each
other, either by using a proper jack plug (Neutrik) or by sleeving the
soldered terminals in such a way that they will always insulate against

the
kind of problems you describe.

The shop it seems chose a crap jack plug and did not sleeve it, and

charged
the customer for this terrible piece of work, which cost him a lot of

money.


I wouldn't be best pleased.



Cheers,


Gareth.


The first time this amp turned up with a blown amp modulle, that was
probably due to non sleeved connector for the "L" channel, I agree there.
I
sleeved the elbow and added spiral wrap to the handle to avoid that
happening again. The next time would be due to bad design of elbow,
internal
shorting. These look robust jacks from the outside. More robust than those
usual right angle jacks on 100 or 150W combos , very low profile ones.
They
can hardly handle 100W from the number of times I've noticed them warming
from compression of the insulation under the rivet-type central connector
,
if not so loose it is intermittant contact.
Any other makes other than Neutrik proven reliable for 150W upwards?




IMHO you should not be using jacks for anything over 150W. Far too Mickey
Mouse, and not designed for that purpose.

I will not use anything other than Neutriks for speaker cables - the cable
grip system is as imporant as the robustness of the jack itself, and
Neutriks (both jacks and XLR's) do not EVER break if wired correctly in the
first place.

Which is kind of what you need really, in a live situation, as failiure of
speaker cables in particular can destroy your amps as well as your
reputation.


Cheers,



Gareth.


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Gareth Magennis wrote in message
...

"N_Cook" wrote in message
...
Gareth Magennis wrote in message
...


"N_Cook" wrote in message
...
Gareth Magennis wrote in message
...



IMHO you should not be using jacks for anything over 150W. Far too Mickey
Mouse, and not designed for that purpose.

I will not use anything other than Neutriks for speaker cables - the cable
grip system is as imporant as the robustness of the jack itself, and
Neutriks (both jacks and XLR's) do not EVER break if wired correctly in

the
first place.

Which is kind of what you need really, in a live situation, as failiure of
speaker cables in particular can destroy your amps as well as your
reputation.


Cheers,



Gareth.



I have one of the original Yamaha 5m speaker leads here. Although moulded
on, I doubt the sleeve was really held even when new. Now ,although not
pulled out of the perforated relief part , you can see the white and red
conductor wires through the perforations , both connector ends, certainly no
sleeve anchoring now.


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Default Yamaha Stagepas 300 failure mode

On Jan 31, 9:09*am, "N_Cook" wrote:
Another identifier , perhaps, for these shoddy elbow jacks, the "hank shank"
section has 32 "teeth" around it


A couple of photos would really have helped to understand the
problem!!!!!!


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wrote in message
...
On Jan 31, 9:09 am, "N_Cook" wrote:
Another identifier , perhaps, for these shoddy elbow jacks, the "hank

shank"
section has 32 "teeth" around it


A couple of photos would really have helped to understand the
problem!!!!!!

++++++++

http://diverse.4mg.com/elbow_jack.jpg
Ground off top section is under D
Tip of D is ground off from the weld point to the left of B
A is the small projection that should locate in end of the white plastic at
B
G locates over small nib of that plastic on the other side
F insulator , still in the stem is not long enough at the other end, for to
stop D touching C
E is the "hank shank" form
Although the cable is anchored firmly at the crimp forks, the "solder tag"
can easily twist if the wires inside the sleeving twist, or looking at it
again , nothing much stopping the tag shifting axially if the whole cable is
tugged . Pulling on the cable dit not ellicit any problem , twisting of the
cable did though


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My Yamaha leads are both the same length and have straight jacks. I have had the cut-out problem (like so many others) and can't remember what leads I was using but ANY other leads I have are high quality ones. The problem seems to be down to the limiter deciding when things are too loud. What is bizarre, though, is that I have had individual channel and master volume levels set to about 10 o'colock (40% - well below the "peak" mark outside the knob) and have seen the red light flash with only two vocals going through the unit. Surely there is someone out there who could work out how to disable this silly limiter?
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wrote in message
...

My Yamaha leads are both the same length and have straight jacks. I have
had the cut-out problem (like so many others) and can't remember what leads
I was using but ANY other leads I have are high quality ones. The problem
seems to be down to the limiter deciding when things are too loud. What is
bizarre, though, is that I have had individual channel and master volume
levels set to about 10 o'colock (40% - well below the "peak" mark outside
the knob) and have seen the red light flash with only two vocals going
through the unit. Surely there is someone out there who could work out how
to disable this silly limiter?

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"Gareth Magennis" wrote in message ...



wrote in message
...

My Yamaha leads are both the same length and have straight jacks. I have
had the cut-out problem (like so many others) and can't remember what leads
I was using but ANY other leads I have are high quality ones. The problem
seems to be down to the limiter deciding when things are too loud. What is
bizarre, though, is that I have had individual channel and master volume
levels set to about 10 o'colock (40% - well below the "peak" mark outside
the knob) and have seen the red light flash with only two vocals going
through the unit. Surely there is someone out there who could work out how
to disable this silly limiter?

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wrote in message
...

My Yamaha leads are both the same length and have straight jacks. I have
had the cut-out problem (like so many others) and can't remember what leads
I was using but ANY other leads I have are high quality ones. The problem
seems to be down to the limiter deciding when things are too loud. What is
bizarre, though, is that I have had individual channel and master volume
levels set to about 10 o'colock (40% - well below the "peak" mark outside
the knob) and have seen the red light flash with only two vocals going
through the unit. Surely there is someone out there who could work out how
to disable this silly limiter?



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Default Yamaha Stagepas 300 failure mode

ffs, something really strange going on with Windows 8 here, every time I
press Return it posts an empty reply.


Cuh

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Default Yamaha Stagepas 300 failure mode

Hmm, seems to work if I delete the original text.


Anyway, the limiter might actually be doing its job and preventing the whole
thing blowing up, you don't want to disable it.



Gareth.

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Default Yamaha Stagepas 300 failure mode

Gareth Magennis wrote:

ffs, something really strange going on with Windows 8 here, every time I
press Return it posts an empty reply.


Cuh

This has been seen on other groups. The suspected mechanism is that
the original post is in MIME-encoded form, and the reply is in
plain text. So, if the replier's mail program just appends plain
text to the MIME-encoded message, some newsreaders will fail to see
that extra text as being significant, as there is no MIME description
of what format it is in. I'm using Knode, and all of your replies
showed up here, with your text in them. If you go back to one of
these "empty" replies and tell your reader to "view source" you will
probably see your message there. Curiously, I did this and the
message is NOT in MIME format, so don't know why it doesn't show
for you.

Jon
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Default Yamaha Stagepas 300 failure mode



"Jon Elson" wrote in message
...

Gareth Magennis wrote:

ffs, something really strange going on with Windows 8 here, every time I
press Return it posts an empty reply.


Cuh

This has been seen on other groups. The suspected mechanism is that
the original post is in MIME-encoded form, and the reply is in
plain text. So, if the replier's mail program just appends plain
text to the MIME-encoded message, some newsreaders will fail to see
that extra text as being significant, as there is no MIME description
of what format it is in. I'm using Knode, and all of your replies
showed up here, with your text in them. If you go back to one of
these "empty" replies and tell your reader to "view source" you will
probably see your message there. Curiously, I did this and the
message is NOT in MIME format, so don't know why it doesn't show
for you.

Jon



Thanks, Jon.

My Windows 8 has been buggy from the start, Live Mail particularly so,
always complaining it can't back up the database because it is in use by
something else (???)

Live Mail is what I use to post on Usenet - I guess its teething problems.


You know the only improvement I can see that Windows 8 has over XP is that
it boots up a lot quicker - seems to keep some kind of "snapshot" on file
somewhere, otherwise it seems to do exactly the same job I ask of it, but
with a whole load of bugs, and I can't find things any more.



Cheers,

Gareth.

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Default Yamaha Stagepas 300 failure mode

I have seen the following problems occuring on StagePas 300 :

People change cables w. "standard issue 10m cables, 6,3mm Jack ends" because they need longer cables. This won't ever work; Most industry standard cables having 6.3mm jacks are meant for guitars and other relevant instruments,Conductors inside are thin and coaxial having enormous capacitance and very large resistance.


You need to order your technician or build yourself a pair of REAL Loudspeaker (twin-lead and sufficient thickness for 150W power handling) cables having mono 6,3mm jacks end to end. You won't burn your amp that way.

also -

I have noticed a problem w. my set that showed after 15 mins of operation the following problem:

Sound cut off, replaced with low frequency hum (thus amplifier is still active), Limiter led (red on bar graph) stuck ON, Turning it off and after a few minutes back on solves the problem.

That problem was traced down to an 7915 voltage stabilizer on the main preamp/psu board, having an output of -8V instead of -15 on normal operation and after 15 minutes that voltage fell to 0 volts. Replacing the 7915 with another fixes the problem (solid -15V on output). My Stagepas 300 has an 7915 with plastic casing (too large heat resistanse to heatsink, I guess, and a semiconductor fatigue resulted to that problem). It looks that using a metallic 7915 is possible as the heatsink is electrically isolated from the rest of the circuit on my revision, if in doubt use some mica - plastic ring isolator there.

Cheers.


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Default Yamaha Stagepas 300 failure mode

On 21/04/2016 09:53, wrote:
I have seen the following problems occuring on StagePas 300 :

People change cables w. "standard issue 10m cables, 6,3mm Jack ends" because they need longer cables. This won't ever work; Most industry standard cables having 6.3mm jacks are meant for guitars and other relevant instruments,Conductors inside are thin and coaxial having enormous capacitance and very large resistance.


You need to order your technician or build yourself a pair of REAL Loudspeaker (twin-lead and sufficient thickness for 150W power handling) cables having mono 6,3mm jacks end to end. You won't burn your amp that way.

also -

I have noticed a problem w. my set that showed after 15 mins of operation the following problem:

Sound cut off, replaced with low frequency hum (thus amplifier is still active), Limiter led (red on bar graph) stuck ON, Turning it off and after a few minutes back on solves the problem.

That problem was traced down to an 7915 voltage stabilizer on the main preamp/psu board, having an output of -8V instead of -15 on normal operation and after 15 minutes that voltage fell to 0 volts. Replacing the 7915 with another fixes the problem (solid -15V on output). My Stagepas 300 has an 7915 with plastic casing (too large heat resistanse to heatsink, I guess, and a semiconductor fatigue resulted to that problem). It looks that using a metallic 7915 is possible as the heatsink is electrically isolated from the rest of the circuit on my revision, if in doubt use some mica - plastic ring isolator there.

Cheers.


The main speaker lead problem is one jack has to be reverse "polarised",
so must be insulated as any stray metal ,eg drummer's snares , will
short an amp to the nice shinning metal handle , conveniently placed
next to the output sockets.
One amp is invertyed relative to the other, to save on volume of rail
caps required on peak demands

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Default Yamaha Stagepas 300 failure mode

On Thursday, April 21, 2016 at 4:53:41 AM UTC-4, wrote:
I have seen the following problems occuring on StagePas 300 :

People change cables w. "standard issue 10m cables, 6,3mm Jack ends" because they need longer cables. This won't ever work; Most industry standard cables having 6.3mm jacks are meant for guitars and other relevant instruments,Conductors inside are thin and coaxial having enormous capacitance and very large resistance.


You need to order your technician or build yourself a pair of REAL Loudspeaker (twin-lead and sufficient thickness for 150W power handling) cables having mono 6,3mm jacks end to end. You won't burn your amp that way.

also -

I have noticed a problem w. my set that showed after 15 mins of operation the following problem:

Sound cut off, replaced with low frequency hum (thus amplifier is still active), Limiter led (red on bar graph) stuck ON, Turning it off and after a few minutes back on solves the problem.

That problem was traced down to an 7915 voltage stabilizer on the main preamp/psu board, having an output of -8V instead of -15 on normal operation and after 15 minutes that voltage fell to 0 volts. Replacing the 7915 with another fixes the problem (solid -15V on output). My Stagepas 300 has an 7915 with plastic casing (too large heat resistanse to heatsink, I guess, and a semiconductor fatigue resulted to that problem). It looks that using a metallic 7915 is possible as the heatsink is electrically isolated from the rest of the circuit on my revision, if in doubt use some mica - plastic ring isolator there.

Cheers.


Mak,
Did you replace the 7915 chip yourself or did you have it done in a shop. I don't trust myself to make this repair but the cutting out problem has made the Yamaha unit totally unreliable so I really need to try it. Any tips would be greatly appreciated.
Thanks J
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Default Yamaha Stagepas 300 failure mode

Where are you located? Perhaps others in the area can assist.

Dan
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