Bogner XTC Blue gain stages

[SacredGroove]

I think what I meant was to switch stage 4 in/out. Anyhow, is there a way I could switch one of the gain stages in/out to have a Red/Blue channel type scenario?

Thanks!

[GainFreak]

I think what I meant was to switch stage 4 in/out. Anyhow, is there a way I could switch one of the gain stages in/out to have a Red/Blue channel type scenario?

If you want the Red/Blue option you'll need to switch stage 3 in/out. Check out the schematic I posted - sw12 does that. You'll need to cut some traces and add a switch.

[SacredGroove]

If you want the Red/Blue option you'll need to switch stage 3 in/out. Check out the schematic I posted - sw12 does that. You'll need to cut some traces and add a switch.

Your schematic is a lot more involved than mine. I was hoping to not cut traces. I'm going to check the schematics to see which trace(s) to cut. Otherwise, I could just re-bias a stage (or 2) for low and high gain with the option to switch between them. Thanks.

[GainFreak]

If you don't want to cut traces but you want more/less gain option then you can add sw11 which is the Structure switch in XTC.

[SacredGroove]

Yep, I was already planning on having a Structure switch. On your schematic is there a Plexi mode switch? I don't see one on any schematic, none that include typical Plexi TS values.

[GainFreak]

Simultaneous operation of sw19 and sw13 (think of them as a single DPDT switch) will give you the Plexi mode.
Concerning the Red/Blue mod mentioned in previous posts you don't need to cut traces but only solder/desolder couple of things and add switches.

[SacredGroove]

Simultaneous operation of sw19 and sw13 (think of them as a single DPDT switch) will give you the Plexi mode.
Concerning the Red/Blue mod mentioned in previous posts you don't need to cut traces but only solder/desolder couple of things and add switches.

I was thinking that the Red/Blue could work without cutting traces, but I didn't have time to test it yet. What were you thinking I could connect/disconnect for the Red/Blue? Should I go from stage "2" plate to stage "4" grid via a switch? Disconnect stage "3" grid and tie in to other side of a switch? Sorry if this doesn't make sense, but I'm going to draw it and maybe it'll make more sense then.

I'll check sw 13, 19 too. Regardless, a Plexi mode is going in...LOL.

[SacredGroove]

EDIT for post above: Stage 2 plate to stage 5 grid. Stage 4 grid to ground. Both of these could go on a dpdt toggle to switch stage 4 in/out. Is this correct?

Thanks!

[GainFreak]

Here's how it should go:

Plexi mode:
- unsolder 1 and 2 (from that side only) from PCB. Connect them together and run a wire from them to the switch. Add 470k/470p combo to the switch and run wires as shown

Red/Blue channel:
- unsolder 3 and 4 completely from PCB and move them to the Red/Blue switch. Run wires as shown

Structure switch:
- change 5 (2k7 resistor) to 4k7. Unsolder 6 (the end that goes to ground). Solder another 4k7 resistor, connect and run wires as shown

[SacredGroove]

Thanks for the thorough info and sorry for the late response. Is the Plexi switch on-on?

Scott

[GainFreak]

Is the Plexi switch on-on?

Yes, all of them. No mid (OFF) position.

[SacredGroove]

Here's how it should go:

Plexi mode:
- unsolder 1 and 2 (from that side only) from PCB. Connect them together and run a wire from them to the switch. Add 470k/470p combo to the switch and run wires as shown

Red/Blue channel:
- unsolder 3 and 4 completely from PCB and move them to the Red/Blue switch. Run wires as shown

Structure switch:
- change 5 (2k7 resistor) to 4k7. Unsolder 6 (the end that goes to ground). Solder another 4k7 resistor, connect and run wires as shown

Can you clarify the Structure switch for me? Where does the ground terminal of the cap go after I desolder it? And does the bottom terminal of the switch go to ground?

Here's what I actually did:
On the Structure switch, I unsoldered 6 (- ground) and connected it to the ground terminal of the new 4k7 resistor. Both positive ends of them are in their respective spots on the board. To the switch, I ran a wire from the ground of the cap to bottom terminal of switch, and a wire from where I connected the cap and resistor to the center terminal. I took pictures, so if you send me your email addy I can send the pics.

End result is a low gain sound with no variation in gain/tone from any switch. Switches aren't working properly, but I made a mistake on the red/blue and maybe the Structure switch. I'll try to fix this afternoon. Hope this made sense.

Thanks

EDIT: I've fixed the Red/Blue mistake. Unfortunately, there is still no difference.

[GainFreak]

Can you clarify the Structure switch for me? Where does the ground terminal of the cap go after I desolder it? And does the bottom terminal of the switch go to ground?

Adding a Structure switch is the easiest of all mods discussed. Check out the schematic again - it's pretty straightforward. I'll explain it again. Change stock resistor to 4k7 (it will stay in place soldered to the board). Desolder 2u2 cap's negative end. Add a 4k7 resistor soldering one end to the cap's positive end (the one that is still soldered to the board). Connect cap's negative end and additional resistor's free end together and run a wire to the switch terminal. Run a wire from the other terminal to the board ground. Check also if your switch is OK before that or short the terminals with something conductive.

[SacredGroove]

Here's how it should go:

Plexi mode:
- unsolder 1 and 2 (from that side only) from PCB. Connect them together and run a wire from them to the switch. Add 470k/470p combo to the switch and run wires as shown

Red/Blue channel:
- unsolder 3 and 4 completely from PCB and move them to the Red/Blue switch. Run wires as shown

Structure switch:
- change 5 (2k7 resistor) to 4k7. Unsolder 6 (the end that goes to ground). Solder another 4k7 resistor, connect and run wires as shown

Adding a Structure switch is the easiest of all mods discussed. Check out the schematic again - it's pretty straightforward. I'll explain it again. Change stock resistor to 4k7 (it will stay in place soldered to the board). Desolder 2u2 cap's negative end. Add a 4k7 resistor soldering one end to the cap's positive end (the one that is still soldered to the board). Connect cap's negative end and additional resistor's free end together and run a wire to the switch terminal. Run a wire from the other terminal to the board ground. Check also if your switch is OK before that or short the terminals with something conductive.

I'll check the switch. As for the wiring, I did as you described above. I probably didn't explain myself right from my earlier post. You're right, it is the easiest mod, but nothing is working and I can't get an LED lit either. I'll check all the switches again. Thanks for the email, I'll send pics in a while. Maybe you'll see something I don't.

[GainFreak]

I got the pics. It looks like the Structure switch is wired correctly. I can't see what can go wrong with this mod except for the switch but that's easy to check by shorting its terminals. If you have low gain sound that means the cap/resistor combo is lifted from ground.