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Re: [Amps] Equalising resistors with HV diodes

To: peter.chadwick@Zarlink.Com, amps@contesting.com
Subject: Re: [Amps] Equalising resistors with HV diodes
From: Traian <yo9fzs@office.deck.ro>
Date: Tue, 21 Sep 2004 10:23:31 +0300
List-post: <mailto:amps@contesting.com>
Hi Peter,

You are right, but unfortunately it is more than the reliability problem.
It seems that counterfeit semiconductors are a big problem these days.

Six years ago we were selling and servicing  some good taiwanese made
computer monitors. The company field service engineer asked me to
use only spares HOT (Horizontal Output Transistor) supplied by them
and no others.
He made  warning about many counterfeit or low quality ones that
were on the market.
The company have sent us as many spares as we had need, all at their
expense, so they had no other interest than good business for making
that ask.

>From five years now, we are selling and servicing monitors produced
by a very serious and well known manufacturer.
The reliability is very good and during these years I received only one
warning about a small batch of lower quality HOT which also
did not affect us. That particular type of transistor is made by a very
reputable manufacturer. So, I think that it may happen elsewhere...

But the info from the source below is some scaring:

http://sound.westhost.com/counterfeit.htm

I was in need for a 2SC2922 for a TS950SD final amp supply.
A supplier here was selling 2SC2922 made by two different manufacturers.
The ratio of their prices was more than 3:1 (!).
The 2SC2922 is mentioned on that web page. I guess that I was lucky,
as at that moment only the expensive ones were on stock.
This may saved me a pair of expensive 50V finals...


73,
Traian



peter.chadwick@Zarlink.Com wrote:

>
>
> Experience also suggests that for best reliability, buy diodes from
> reputable manufacturers - some of the far Eastern ones are distinctly dodgy
> froma reliability viewpoint.
>
> 73
>
> Peter G3RZP
>
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