Russian BMP. Tone control acts like a volume?

[BillyJ]

Anyone had this problem?
Guess I will begin debugging tonight but thought I would ask about the schematic.
Which one do I use from schematics? or is there a diffeent one for the russian?
I iwll go through the geo steps of debugging but anyone want to guess what the problem is? or can tell me how to test just the tone pot?
I know it is in the FAQs... Just had to ask though...my bad.
I am still pretty bad at debugging..

[idlefaction]

you mean the green one?  i've had a look in a few of them, the circuit is the same as the 'triangle' bmp schem at aron's schematics page.  something i've noticed about them is that the tracks on the PCB are really really weak, so maybe one is broken - have a look for hairline cracks in the tracks around the tone section.  it's pretty hard tracing where that is tho cos all the wires are the same colour!!!

looking at the part of the tone circuit where the input gets split to a cap and a resistor, if that cap went bad or had a track broken then the signal would indeed see the same filter all the time and act like a volume control - but it would only turn the volume down to about 1/3 volume with it all the way to the 'bass' side.

good luck  

[BillyJ]

Hmm...Actually this one is black with kinda yellowish lettering.
It said sovtek with some russian writing undrneath that...
Is this a different beast? Wonder if the same schematci applies?
This one one turns completely off.
I will fudge with it as soon as I can.
Will get back here and ask more if I get stumped or just to tell what it was.
Thanks!

[jimbob]

I have the same one. Im looking for mods for it. I really like this pedal, i just think it needs a little harder edge.. The sustain is great though.

[BillyJ]

Yep that was it.  Jeez I left this on a shelf forever and went back to it and sure enough it didn't turn down all the way. I could have sworn it did before.
Thanks for the tip. I wasn't sure which cap you were talking about. I changed out two a .0047 and a .1 or .01 (I forget) but it works great now.
Many thanks for the help.  

[idlefaction]

heh yay!  makes me happy.   :lol:  :lol:  :lol:

jimbob, if you're still out there, try swapping the first set of diodes for LEDs, or maybe just one of the diodes.  sounds kinda 'crunchy-er'  

[eliktronik]

If you need someone to translate Russian for ya, let me know...