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Author Topic: Headphone distortion induced by unused headphone extension cable?  (Read 17538 times)

John Roberts {JR}

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Re: Headphone distortion induced by unused headphone extension cable?
« Reply #30 on: November 20, 2012, 08:16:35 PM »

Yup, it's always something.

@ Mark: You can remove SMD parts with a conventional iron (assuming it has a small enough tip), and you are careful. If you want to have fun you could try to play chopsticks with two irons, one for each end of the part, but I did lots of rework with just a basic single iron before investing in a hot air station. 

I have found that sometimes it is easier to add a touch of fresh solder to improve wetting (added flux from the new solder makes it easier to melt old solder), and try to lay the tip across the top of the part to melt solder on both pads at same time. You don't need to worry about overheating the part, since you should just discard them, but you do need to be careful about overheating the PCB and possibly lifting lands. Tweezers might help, but parts that small will often lift and stick to the iron from surface tension once free from the PCB.

Sounds like a good project to bust your SMD cherry on....

JR

@Steve... I ASSume the service guys get copied on ECNs like that. It was probably identified through a customer complaint (albeit years ago). Not always simple to connect the dots when dealing with lots of SKUs.  I know how that goes....good luck.
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Mark McFarlane

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Re: Headphone distortion induced by unused headphone extension cable?
« Reply #31 on: November 21, 2012, 04:05:16 PM »

Hey, I'm back and getting caught up from vacation. Indeed, there was an ECN (Engineering Change Notice) in 2009 that removed the output stage feedback capacitors since certain loads (like your excess unterminated cable) can cause a low-level noise with certain positions of the front panel knobs and certain impedance headphones connected in front. Fascinating....

Thanks Steve for researching this and for your thorough response and pic.  I'll try to pull the amp from the rack in the coming days and try removing the caps.  I'm in the middle of mixing a CD for a band out of Boston but this sounds like a good ear break activity.  If I get nervous I'll carry the unit back to the States over Christmas and send it in.  I'll be Stateside for about 3 weeks.
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Mark McFarlane

Steve Macatee

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Re: Headphone distortion induced by unused headphone extension cable?
« Reply #32 on: November 21, 2012, 09:42:39 PM »

... I ASSume the service guys get copied on ECNs like that. It was probably identified through a customer complaint (albeit years ago). Not always simple to connect the dots when dealing with lots of SKUs.  I know how that goes....good luck.

Yes. ECNs are easily found internally (if you have the serial number) and everyone in the building can access them. Rarely do our service communications initially know serial numbers - thus it's near impossible to know what ECNs apply at first. But there are a whole bunch of ECNs since we have many products and even the simplest change requires an ECN. Thus, you can easily start ignoring them or being lost in the large pile. Our most common change is vendors changing parts out for discontinued ones - and this trend is increasing in frequency all the time. Ugh.
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Stephen R Macatee   Direct phone: 425 551-1818
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Rane Corporation   www.rane.com   425 355-6000

Mark McFarlane

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Re: Headphone distortion induced by unused headphone extension cable?
« Reply #33 on: December 07, 2012, 02:37:00 PM »

...
I was able to duplicate your problem here today by adding these caps back in to a new HC6S and duplicating your set up. The solution is to remove these two caps on each of the 6 output stages. We can of course remove these for you here at the factory since these are surface mount parts. Alternately, if you're handy and you've got a soldering iron (and good eyes or a magnifying glass) or a small sharp pair of cutters, you can remove the parts yourself....

Thanks Steve and JR.  I finally got some down time this afternoon and unsoldered the caps. Seems to have worked like a charm, no more distortion in my quick tests.

It took two pairs of stacked reading glasses and a magnifying glass.  Wow those surface mounts caps are small ! I'd hate to try to put them back on :)

Thanks again.

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Mark McFarlane

ProSoundWeb Community

Re: Headphone distortion induced by unused headphone extension cable?
« Reply #33 on: December 07, 2012, 02:37:00 PM »


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