wanna help me figure out how to true-bypass a dean markley overlord?

[Luijo]

Nope, sorry to disagree with you, but if you examine your schem closely you clearly see a Q1 AND a Q2 (they are diff FETs, one is a 2SK30A and the other a 2N4383, but the numbres are not very clear). The connection you see between them ( A ) is there to show you they share a common connection for their control signal, nothing else, so they work at once. The opamps are 4558, dual opamps and all four stages are being used, two in the switching and two in the signal path. The first stage of the 4558 involved in the signal proccesing is just a buffer while the second stage provides the actual distortion, which is then smoothed out by the valve following it.
Mark's explanation of the roles of each "Q" is dead on right so if everything else is correct there must be a second FET hiding in there somewhere or the schem must be of a different pedal. The fact that so far the schem matches your pedal (though you admit not tracing it completely) just reinforces the fact that there must be another FET somewhere.

[methodofcontrol]

there is DEFINATELY only one FET on this board. it is a "K30A" as written on the FET itself. i see that the "second" FET is labled as a 2N4383.....but "Q1" is written next to both drawings. someone was obviously confused when drawing this up. in any case...there is only one FET. i have removed it. but the pedal still switches as it used to. it is not in a constant state of "on". any other suggestions? i will try to trace the pedal out to confirm the schematic next time i have an hour free. but i will certainly entertain any questions or advice in the meantime.

[Steve Conner]

There must be a second FET in there somewhere! :-0 As I understand it, one of them lets the clean signal pass to the output while the other one (the lower one squeezed into the schematic) shuts off the distortion stage by giving it lots of negative feedback. This lowers its gain drastically when the pedal is in clean mode, and stops it buzzing through onto the clean channel.

Anyway, either there's a second FET that you didn't remove, or else you accidentally solder bridged the gate terminal of the FET you did remove to one of the other terminals.

P.S. Cute trick, how they made the flip-flop from two op-amps.

[methodofcontrol]

ok... i got to the bottom of this.
to clarify...."yes" there is only ONE FET on the board. i'm certain of this. there's
only so many places a componant can hide on a 3"x2" circuit board.
to my own embarassment, i wasn't listening to the pedal after i removed the FET, i was only using a dummy plug and watching the LED come on and off w/ the switch. the fact is...removing the FET did put the circuit in a permanent "on" position. the green LED, however still turns on and off w/ the momentary switch.
i had it in my head that the FET also controlled the LED. so the fact that the LED still went on and off made me believe the circuit was doing the same. sorry guys. i will be wiring up my true bypass switch tonight or tomorrow. the tone controls suck on this pedal, i may be modding them as well. i'll post my questions/observations/progress. thanks again for the help.

[Mark Hammer]

First off, kudos to you for your humility. Looks good on you, man.

Second, glad you sussed it out. I'm still kinda mystified about how DM is able to accomplish switching with but a single FET but so be it.

You might want to tinker with the Duncan Tone Stack calculator - http://www.duncanamps.com/tsc/ - and figure out what sorts of mods you might want to do to the Overlord tonestack. Give us a sense of what kinds of tonal tricks you need it to do and perhaps we can suggest some mods and component values.

[chocopower]

Hello!!

I bought a Overload last week and IT HAVE TWO FET.

So.... if i a want to change it to true bypass..... Should i cut them???

[methodofcontrol]

simply removing the FET's does not make your pedal true-bypass. removing the FETs should make the switching mechanism obsolete, so your pedal will always be "on". this is the first step to true-bypass'ing a pedal. do you know how to wire up a 3PDT switch for true-bypass? if so...you should have all of the info you need. if not...i can show you how to do it.

[chocopower]

thanks!!

I´m try to do it my self.
If i have any problem.......i´ll post again.


best regards from spain!!!!!

[chocopower]

Hello again!!

I´m thinking in change some value in my Overlord tonestack for more mid definition and more controlable treble...
This is the tonestack. I need help to identify all the conponents to translate them to the Duncan´s Tonestack Calculator



C9: TREBLE CAP
C10: BASS CAP
C11: ¿?¿?¿?¿
C12: MID CAP

Is this correct?

If i up tha value of R16 i supouse it get down total gain.....¿?¿?¿

best regards fron Spain

[chocopower]

Hi again!

Comparing and Overlord and a Chandler tube drive.... i saw the Overlord have 2 JRC4558 chip and the Chandler just one.
I asume this make the Overlord more "High-gain"...
Are there any way to make switchable one of the chips in the Overlord?

Regards!!