Meathead Deluxe clone with Filter bypass - questions

[bamslam69]

Hiya everyone.
I picked this pedal up yesterday in a "not working" condition.
A Jupiter Effects Meathead Clone with Filter Bypass switch. It looks cool IMO

The guy I got it off accidentally plugged the wrong polarity supply into it (mixed up cables apparently).

The photos are in the next post, as is a layout I've managed to find somewhere on the google.
It seems to work, and fuzz, but the led is dead...  I'll get onto that.
I'll check all the transistors today (need to get a new battery for my multimeter that has a transistor tester built in.)

Q1 = 2n3904
Q2= ME4003?

I'm not sure of the footswitch board, there's a N7000 transistor and a 1N914 diode. Hopefully someone could enlighten me on what that's supposed to do? Also if there's anything else I should check as far as reverse-polarity cookups go?

Thanks in advance

[bamslam69]

[bamslam69]

[andy-h-h]

Are you sure about this?   I thought meatheads were NPN silicon???   The photos of the box above seem to point in that direction too.   The layout above is positive ground.   

There's a decent chance the power supply might be running through a capacitance multiplier if an extra transistor is involved, or maybe a millennium bypass switching for the LED.   

[bamslam69]

Nope I'm definitely not sure about this! haha
But the layout seems to match the pedal - I'll go through with a magnifier and see if I can get the right cap values.

I'm just trying to work things out before I go pulling it apart for no reason.

[idy]

Yes, looks like the stompswitch is DPDT, so the MOSFET and diode are proabably milenium/rat bypass for the LED. Look it up. Its a way to get "true bypass" and an LED from a two pole switch.

Very unlikely that a charge pump is being used, where is there an IC? And why would one be used for a NPN circuit?

Checking the Transistors sounds like a good idea. Not sure what other components could have been burned out.

[idy]

Guess you should test the electrolytic capacitors. I see on schematics a 100uf. Is that on the stomp switch board?

[bamslam69]

Nah, all that's on the stomp switchboard is 3 resistors, the Mosfet and diode.

And thanks heaps for pointing out the rat bypass. I'll start my googling.

Edit: problem solved. Replaced both diode and mosfet. Light works, all transistors seem fine.
And the pedal screams nicely!!!
Thanks once again!

[willienillie]

says "MB" on the switch board

[bamslam69]

says "MB" on the switch board

At the time it meant nothing to me.

[andy-h-h]

Good to see the system working    

[duck_arse]

says "MB" on the switch board

At the time it meant nothing to me.

ohh, Vienna.

[bamslam69]

says "MB" on the switch board

At the time it meant nothing to me.

ohh, Vienna.

Geez I had to look that up too!
Damn you Duck! Hahahaha

[duck_arse]

says "MB" on the switch board

At the time it meant nothing to me.

ohh, Vienna.

Geez I had to look that up too!
Damn you Duck! Hahahaha

sorry. I think I've ripped that one off bluebunny.

[bluebunny]

sorry. I think I've ripped that one off bluebunny.

Maybe, dunno.  It's a favourite of a pal of mine, so much so that it's become automatic.

me: I just got an update from those d!ckw@ds in Vienna.

him: It means nothing to me.

me: What??  Oh... <facepalm>

Another mate will automatically regurgitate the "don't call me Shirley" line...   
___

Anyway, back to the grown-up discussion...