On 27/02/2015 1:52 PM, Phil Allison wrote:

Hi,

came up against this strange affliction some time back so maybe now
is a good time to report it. Busker's Disease affects guitar leads,
making them behave intermittently.

You will not find any fault with a continuity tester or visual
inspection of the wiring at each end - but the damn lead is unusable
cos the signal keeps cutting out when plugged into an amp and
guitar.

So what is the cause ?

Unlike other musicians, buskers perform on footpaths and other open
spaces with concrete or tarred gravel surfaces. So, their jack plug
leads get dragged across those same surfaces, wearing off all the
plating on the edge of the tips - exactly where signal contact is
made when inserted into a jack socket.

Under magnification, tip edges look heavily cratered - like the moon.
The previous nickel or gold plating is all gone and bare brass
showing through, with tiny bits of gravel and dirt embedded in it.

A good rub with a kitchen scouring pad, followed by some WD40 on a
cloth will usually get them working - but this is only a temporary
fix. The plugs are ruined and must be replaced.

Of course, you may not be given the diseased lead to check, but an
amp or guitar that is mistakenly being blamed for an intermittent
fault.

Impossible for a tech to figure it out, if nobody tells them the
owner is a busker or does not bring the leads along too.


**Had a similar experience a few weeks back. Customer said "smoke came
out of the tweeter". A little bit of questioning and I requested that he
bring the speaker, both (mono) amplifiers, preamp and the pre - power
cable.

"Hopefully, it's just a resistor in the crossover. I read it on the 'net."

Yeah, right.

This is the speaker:

http://elac.ro/FS_607_rev-hifiworld.html

Look at the close-up photo of the tweeter. The ring around the edge is
the midrange driver. The yellowish thinkg in the centre is the ribbon
tweeter (looks more like Heil driver to me). It was smoked. Easy enough
to pull apart (those whacky Krauts make it pretty easy to strip down).
Beauty, I thought. I'll order a new diaphragm, replace it and everyone
will be happy. Cost of diaphragm? I figure $3 Bucks to manufacture.
$50.00, by the time it reaches me.

Nup. I had to buy the whole ****ing midrange/tweeter. $746.00 delivered.
The importer claims to have done me a huge favour on the cost. I could
not, in all conscience make a profit on the driver, so I passed it to
the client at cost.

I checked the preamp and power amps. No problems. The interconnects,
OTOH, were some wanky audiophile bull****. I was able to simulate an O/C
on either earth or active at various times. I presume it was causing
some instability in one of the power amps.

THEN, the customer told me that he had been running the system for many
months with no problems. The fault occurred after he had purchased some
new cables...........

Anyway, I fitted some Polyswitches to both tweeters. Just in case.

Oh yeah, I told him to send the cables back for a refund.

FWIW: The speakers sound fabulous.



--
Trevor Wilson
www.rageaudio.com.au

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