Maestro BG2 Wah pedal identifying parts

[jimitrader]

Maestro BG2 Wah pedal identifying parts
Maestro BG2 Wah pedal schematic



partial list of parts listed in pic below..some of these parts are hard to see the value code?

anyone want to share a few better pics of your pedals guts?

[jimitrader]

i am thinking the cap in bottom right corner = .047

cap just above inductor = 6 +/-

between 5.6k resistor and 1 uf top left corner = .01

[jimitrader]

here is the update what do you guys think?


Mine has sept 14 1967 stamped on board ..i am thinking transition year with bg1 parts in bg2 case bg2 board - also has the white inducter ? someone took mine apart before me and i am trying to recreate it..i have most of the parts including inductor & board just missing some caps an resistors
after the resistors and capacitors I need to figure out orientation of the 2 transistors

NPN 2N4401

[jimitrader]

i have re assembled the board and have connected everything and i just get a vol pedal on both on/off? does the inductor have to go in a certain way or can it go either way?

[antonis]

Inductors don't have polarity..

[jimitrader]

Inductors don't have polarity..

Thanks ...

[antonis]

Some circuits for inductance (brute) measurement..

https://www.homemade-circuits.com/15-v-inductance-meter-circuit/
https://www.edn.com/cheap-and-easy-inductance-tester-uses-few-components/
https://michaelgellis.tripod.com/68hc11/ind.html
https://sound-au.com/project121.htm (figure 4)

[jimitrader]

Some circuits for inductance (brute) measurement..

https://www.homemade-circuits.com/15-v-inductance-meter-circuit/
https://www.edn.com/cheap-and-easy-inductance-tester-uses-few-components/
https://michaelgellis.tripod.com/68hc11/ind.html
https://sound-au.com/project121.htm (figure 4)

thanks!! hey i got wah sound! i re-built it with the bg-1 schematic on breadboard and it works great i also switched from 2n4401 to 2n5088 248 HFE ...my board says 1967 so maybe it was thew transition year? will go with it...i like how it sounds! thanks again!!

[mozz]

I may have the correct cross for those transistors on a file, will look it up when I get home from work. 200-250hfe sounds about right.

EDIT: Can't find any info on that number. 991- are usually Lowrey numbers which was owned by Gibson (parent company)at that time.

[jimitrader]

pedal is sounding great now that i rebuilt the bg-1 schematic...only the volume control side is kind of quiet ? was this normal? how can i get the vol pedal side to be normal vol ? its not the pedal adjustments? as i went over those very carefully watching a video of the guru guy..and with out being in the pedal just turning it you get a small tone change on vol side? an thats it? any thoughts?

[Rob Strand]

From what I can see maxing out the volume should provides some gain.
Volume mode does lose some upper highs.

Perhaps measure the DC voltages on the collectors of the transistors.  That might show-up some problems.
Transistors with gains around 220 should work - which agrees with mozz's recommendations.

You can bump the gain by increasing the 5k6 to 10k, or  something in between.   At this point it shouldn't be necessary.
(If you want to keep the existing 5k6 resistor add series resistors.)

[jimitrader]

how about a complete bypass? I am trying to figure that out so it would be like this.

• Wah mode
• True bypass mode (no vol pedal) this works if i disconnect the battery while in volume mode otherwise get vol drop if sleeve of in jack connected to ground of bat clip

anyone good with switches ? I have a spdt and i have seen them in gut shots of bg-1 models

this is the schematic that i am working with now

[Rob Strand]

As shown the bypass mode sucks tone.   The 25k pot and the 10k collector resistor gets connected across the pickup that's going to kill the tone and knock back the level a bit.

True bypass will fix the problem for sure.   Everything else is a compromise.

One solution is the buffered input (as per 1990's and beyond Dunlops) but that changes the way the wah mode loads the guitar and isn't favored by some players.

Switching out batteries generally ends up causing "bangs" when switching.  A few old 60's pedals switched out the ground to float the whole circuit (and as a result the power gets switch out).   I think that works but gives a bang.

[edited]

[jimitrader]

thanks Rob... I will a tempt a true bypass ..there is not a lot of room for a 3pdt. maybe i will re-do the pcb an make more room .any tips on setting up true bypass?

[antonis]

any tips on setting up true bypass?

[jimitrader]

 antonis thanks ...I have it done now and will try an read up on posting a video for reference.. for other people..not a whole lot of info on the off board wiring..guess it becomes automatic when you get at a higher level..

[antonis]

not a whole lot of info on the off board wiring..

Take your time while studing the diagram below:



P.S.
Can't find at the moment another diagram which basically is a variation of the above with all 3 switch options (No IN-OUT grounding, IN grounding only and IN & OUT grounding)

[antonis]

Promise consummated..