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N_Cook N_Cook is offline
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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