weird problem

[merlyner]

i built a clone of the rangemaster, modified to switch between input caps as well as pulldown resistors, and it doesn't boost the sound but reduces it and when i turn the pot clockwise the sound decreses more untill there is no sound.  What the hell! can anybody help me?

[Jason Stout]

A small value pull down resistance will pull down the signal as well.....

[zener]

Is that pot wired like a volume control? It could have been wired backwards, I mean you could have swapped the points of lug1 and 3 that's why sound is decreased as you turn it clockwise. Try turning the pot counter clockwise. If the sound get boosted, then my suspicion is correct. If not, then it is something else.

The same thing is true even with a pot wired as variable resistor (lug2 is shorted with either lug1 or lug3 per schem).

Also, pulldown resistors should be 1M or higher.

[merlyner]

the pulldown resistors are 1m and the pot is wired correctly.

[merlyner]

help please!

[Eric H]

i built a clone of the rangemaster, modified to switch between input caps as well as pulldown resistors, and it doesn't boost the sound but reduces it and when i turn the pot clockwise the sound decreses more untill there is no sound.  What the hell! can anybody help me?

Did it boost --before-- you modified it?

[merlyner]

i don't know, i didn't try it without it being modified

[Jason Stout]

merlyner wrote:

i built a clone of the rangemaster, modified to switch between input caps as well as pulldown resistors, and it doesn't boost the sound but reduces it and when i turn the pot clockwise the sound decreses more untill there is no sound. What the hell! can anybody help me?

Eric H wrote:

Did it boost --before-- you modified it?

How is the switching being done? ie How is it wired?
What are you trying to switch between?
What values are the capacitors?
What values are the pulldown resistors?

merlyner wrote:  

when i turn the pot clockwise the sound decreses more untill there is no sound.

The pot is wired backward, (I do this all the time) swap the wires on the outside lugs of the pot.

[Mike Burgundy]

okay, I don't see how a pot wired like a volume control could decrease volume when rotated CW, so at least there's *some* wiring error in there.
It's not a hard circuit. First rebuild the original, get that working, and mod from there. Make sure you get transistor pinout right (take heed: for some trannies different brands have different  pinouts. On most (all I know, anyway) germanium the marked pin (metal cans) is not the emitter but the collector)
Don't be phased when something doesn't work straight away, it's usually quite simple mistakes that we all make (everyday, too   ) :cry:

[Eric H]

First rebuild the original, get that working, and mod from there.

Exactly --sometimes I'm too cryptic. Great post, Mike.

-Eric

[merlyner]

thanks so much guys i am gonna go try it.

[merlyner]

well, i tryed the tranny pinout reversed and it sounded alot better but still not like i thought it would sound.  maybe my amp has to be cranked (it's 12 at night, rents sleepin).