[sdiy] Vox Continental key noise

Michael E Caloroso mec.forumreader at gmail.com
Sat May 1 06:28:26 CEST 2021


I don't think you can eliminate the noise.  Vox combo organs are cheap
designs, the contact noise is DC transients when the contacts mate.
In an isolated setting you may notice the contact noise, while in a
band setting it will be masked out by all the other instruments.

Don't expect these to be high fidelity.

MC

On 4/30/21, Nathan Trites <nathan at idmclassics.net> wrote:
> Hi all,
>
> I've got a continental v301e here where I'm getting a nasty contact noise
> on all keys, which varies in level (seemingly due to where the waveform
> falls). It's definitely not just dirty bus bars & j wires, which have been
> cleaned pretty aggressively. Most of the finger connections seem good, all
> electrolytics replaced, and a few of the (film?) caps replaced for being
> open.
>
> With all tone boards in, each bus has an offset of low double digit
> millivolts. With a single tone board in it still occurs with an offset in
> the single digit mV and it still happens. I've replaced coupling caps in a
> few and they still have noise.  I can see the spikes on the scope even
> without the preamp board installed. Would such a small offset cause popping
> like that on the switches?
>
> The continental is a fair bit older than gear I'm used to working on so I'm
> still getting my bearings on the construction and haven't checked this yet,
> but I suspect the ground from the draw bars or going to the tone boards
> needs to be looked at closer.  I do get some very low noise on the power
> supply (even with nothing installed) again in the 10s of mV range p-p.
>
> Schematics can be found here:
> http://www.theamericannight.com/voxproject/project.html
>
> Any guidance or advice would be appreciated! If anyone knows of a good
> transistor organ repair forum or list that would be very helpful too.
>
> Thanks,
>
> Nathan
>


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