Millennium bypass help

[Barcode80]

okay, so i have this green russian big muff that i converted to true bypass and built a buff n blend into and it works great! only problem is, the latch on the stock switch broke a while back turning it into a momentary switch. turns out, the bass player friend i have who i am odding the pedal for loves it, so he doesn't want me to change the switch, but he wants an LED. enter the millennium, right? well i'm stumped.

i made the exact board on RG's site, soldered the parts in, using a bs170, the C-B junction of a 2n3904 as the low leakage diode, 4148 for the other. 2.2k current resistor for the LED, and parts are oriented exactly how the site says (though i accidentally printed the board backwards, but i just flipped the layout). i searched and searched but couldn't find a post about how to wire the switch, so i wired it according to how the millennium and switch are wired in the lpb project on tonepad. bypass works, effect works, blend works... LED does not. LED has been tested out of the circuit. so i'm wondering where to start debugging this 5 part circuit?

[R.G.]

The Millenium does not need the rest of the effect to work. Power just the Millenium board, and leave the Millenium control line open. The LED should come on. If it does not, check that the pinout on your specific manufacturer's BS170 matches what the board wants; get the datasheet and check pin by pin.

If that matches, solder one end of a 1M resistor to the control line. Touch the unsoldered end to +9V. Does the LED come on? If yes, the 1N4148's are inserted wrong or faulty, or do not have high enough leakage. Check that the band/cathode end is attached to +9V and that the anode end actually connects to the BS170 gate. Still doesn't work with the 1M resistor supplying input? If so, add one or two more 1N4148's in parallel with the one that's in there now. Work now? If yes, you got "modern" 1N4148's, which have lower leakage than old style gold-doped-junction 1N4148s. Leave the extra 1N4148's in there.

If the LED does not come on, remove the 2N3904. Work now? If yes, the 3904 was backwards, wrong junction or shorted. Check the gate for shorted to ground while the 2N3904 is out. The 3904 is a protective diode, not needed for basic operation.

If it still doesn't work, you may have a dead BS170, possibly killed by static electricity.

The Millenium Bypass is a simple circuit, but it's by a couple orders of magnitude the most sensitive circuit that is used in effects circuits. The currents which cause its switching are so small that they are hard to measure correctly in labs, and can't be measured with home methods at all.

[Barcode80]

sweet, thanks for all the tips. i'll try them all. i just realized i made a post over a year ago where you showed me how to wire it too... 

[Barcode80]

okay, now it comes on and i can't get it to switch off.

[Barcode80]

nevermind, thanks for all the help! i got it working. had to change out the bs170, flip a diode, and put in that parallel diode like you said. works like a charm!