Yamaha Stagepas 300 failure mode

[N_Cook]

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.

 

[N_Cook]

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

 

[N_Cook]

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

 

[N_Cook]

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

 

[N_Cook]

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

 

[N_Cook]

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

 

[N_Cook]

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?

 

[N_Cook]

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.

 

[N_Cook]

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 isbizarre, 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?