tayda purple plexi - tone pot affecting volume

[pete74]

Hi guys... recently built a tayda purple plexi clone and love how it sounds (here it comes.....) BUT, the tone control, when all the way down, completely kills all volume.  That being said, when it's all the way up, it seems to be adding gain as well.

Here's the info they provide to the builder: http://www.taydakits.com/instructions/purple-plexi-800/pages/designators-and-components--21

Sadly, they don't provide any schematic for this unit.   Any thoughts on where a relative noob should look when approaching this?

[antonis]

Any thoughts on where a relative noob should look when approaching this?

Sadly, on any relevat schematic.. 

[GibsonGM]

assure yourself that you did it right.

That includes looking at what value the pot is!     LOL! 

[antonis]

So, let us see..

http://4.bp.blogspot.com/-dTQiHUh7GpQ/TxDAQBZ9mrI/AAAAAAAAAgQ/23s3-GSbJiI/s1600/pedafl.png

The ratio of R6//Freq pot / R7 is about 1.4 when pot is all the way down, so you have an about 60% signal attenuation..
(ignoring C7 impedance at low frequencies.. )

This isn't enough for completely killing volume, so something happens either on R7 value/connection or on what Sir Mike said...

[Mark Hammer]

This looks like a job for the SWTC...whose primary purpose is to be able to filter out highs without changing the volume setting.
The taper of the  tone control might change a little, but the net effect on tone would be the same.

[pete74]

So, let us see..

http://4.bp.blogspot.com/-dTQiHUh7GpQ/TxDAQBZ9mrI/AAAAAAAAAgQ/23s3-GSbJiI/s1600/pedafl.png

The ratio of R6//Freq pot / R7 is about 1.4 when pot is all the way down, so you have an about 60% signal attenuation..
(ignoring C7 impedance at low frequencies.. )

This isn't enough for completely killing volume, so something happens either on R7 value/connection or on what Sir Mike said...

The pots I'm using are mounted on the PCB...   as for R7 value, what SHOULD it be?  The link you shared was interesting as it's slightly different (R6, R7, C1,C2 & C6 + diodes) than what was provided from Tayda to me.   R7 is one of the differences...     

[pete74]

SIGH... or maybe, stupid me didn't catch a bad solder joint on R7....   Thanks all.

[antonis]

something happens either on R7 value/connection or on what Sir Mike said...

(Obviously, you owe me another gained bet list beer, Sir Mike..) 

@pete74: Most of the time is something "stupid" like that.. 

[GibsonGM]

assure yourself that you did it right.



That includes looking at what value the pot is!     LOL! 





Unfortunately I modified my previous post by copying out and saving...