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Re: [RFI] Low pass filter opinions

To: RFI RFI <rfi@contesting.com>
Subject: Re: [RFI] Low pass filter opinions
From: dalej <dj2001x@comcast.net>
Date: Thu, 13 Jan 2011 17:08:53 -0600
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
I won't bet, but yes, I did actually take the cover off of this Behringer box 
and what I found was like you said, a long PCB with the XLR and TRS receptacles 
mounted on a long PCB.  Pin 1 on each connector went to a long trace on the 
board to a point where a green wire was attached, that green wire went to a 
chassis stud with star washers which also held another green wire from the 
mains ground point. I have a Mackie mixer VLZ 1201 pro or something like that, 
which has also a long PCB where the connectors are mounted, I had the cover off 
of it too, but I should take another look to see where that pin one ground is 
going.  This Mackie mixer of mine was mfg in the USA.  I understand the new 
one's are made in China.   And yes, I've heard the same about Behringer.  They 
set the trend for low priced audio gear.  

Would it be best for me to run a separate wire from each XLR pin 1 to the 
nearest point on the chassis, which might require drilling holes?  Or perhaps 
one hole drilled in the chassis at the opposite end of the PCB with another 
wire to a stud there.  I'm not planning to sell this as it has no second hand 
value so drilling holes is not a big deal as long as it's not in the front 
panel.  

This RFI stuff is quite frustrating when you got it, but when you find and fix 
it it suddenly becomes quite satisfying, hi.

73
Dale, k9vuj


 
On 13, Jan 2011, at 15:56, Jim Brown wrote:

> On 1/13/2011 3:43 AM, dalej wrote:
>> I have a Behringer MX882 used in a splitter configuration so that I can feed 
>> three rigs with one microphone.  Anyway this morning I used my Fluke 77 and 
>> checked the input pin one to chassis and it showed zero ohms all looks good 
>> so far.
> 
> Unfortunately that tells you nothing. I'd bet a six pack of some really 
> good Belgian ale that the Behringer has pin 1 problems.  You can't 
> measure this with an ohmmeter (because the resistance of a circuit board 
> trace is usually below the threshold of what a meter can measure), 
> you've got to take it apart and look at it, or you can use one of the 
> test methods outlined on my website.
> 
> BTW -- Behringer has a REALLY bad reputation in the audio world for 
> lousy quality, lousy support, and lousy business practices.  They are 
> well known for stealing designs from other mfrs, were convicted in a 
> German court of doing so, and settled out of court on several other 
> suits. In one case I know of (a Mackie mixer) they copied the cabinet, 
> the external design and layout, mistakes on the printed circuit board, 
> including pin 1 problems, and bought so many of the OEM faders that they 
> were out of stock at the mfr when Mackie tried to buy them! And it was 
> an OEM part for Mackie! (For the non-engineers among us, an OEM part is 
> one that is not in the catalog, but is a unique part built to spec for a 
> customer to fit into their products.)
> 
> 73, Jim K9YC
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