booster works only on bridge pickup

[CoolJohnny]

built a simple booster for my first perfboard project (have built many others successfully from already traced pc boards, PAIA, GEO, etc.).

learning a lot by just subsitituting parts values, etc. but the one thing that is weird is this; i'm using a fender american strat into a clean fender bassman to test the circuit. its a nice mild boost that doesn't distort but adds a bit of thump to the signal (like having the amp on 6 instead of 2).

but it only seems to boost when i select the bridge pickup. the other pickup positions (all of them) exhibit an extreme drop in volume so that the effect is that of a "volume limiter." anybody esle experience this? any ideas? thanks...

[petemoore]

No, or we doubt it. The booster should amp whatever the guitar puts into it...

[CoolJohnny]

i know...its friggin' weird, isn't it. its never happened before. i do have the strat wired for seven positions but the effect is the same with the switch on or off. strange. haven't tried it on any other guitars yet...maybe that will reveal something.

[DDD]

It seems your pickup selector switch needs service\repair.

[CoolJohnny]

that was my first thought. unscrewed it, check the points, dusted it with some canned air. still happens. weird man, weird...

[vanhansen]

Is this booster built in to your guitar or is it an outboard stand-alone stompbox?
Do positions 1 thru 6 sound thin and lose volume without the booster engaged?
Have you done any wiring mods other than the switch change to your Strat?