HIWATT DR103 Unused V2 Triode

[idsnowdog]

I built a preamp board last month for an early seventies DR103 and I was able to find a schematic and layout for the Trinity TRIWATT last week which is relatively similar to the HIWATT DR103. The TRIWATT has a push/pull pot that uses the unused V2B triode as an overdrive that I would like to add to the DR103.  I think I have identified the components that would need to be added. So, I cut the board and spliced in a new section for the OD control.  I was able to identify most connections but the part in purple is still iffy.  Any help would be greatly appreciated!

[CascoSieg]

Hmmm... the snip of your revised layout seems incomplete (missing a pot, switch, and wires running to V2a). The 22n cap is probably the coupling cap from the OD/boost stage and the 2.4k resistor could be a cathode R, but I can't tell from what you've included - I'm probably missing something.
Do the Trinity layout and schematic not provide enough info?
I'm not as experienced as most here, but I've built this very thing, so I'm happy to help if I can.

[idsnowdog]

I added the push/pull. I am not worried about the tube socket connections yet.  The 22n is a coupling cap.  The 2.4K is a cathode resistor.  The 100K plate is a Dale RN55 and it has a 200pf capacitor to cut treble and prevent oscillation. Thanks for your help.

[CascoSieg]

I think you'll have better results if you develop your modified layout in a tool that is meant for doing just that, like Express SCH or DIY.  It's a small investment of time, for a lot of value. I'm not trying to be flip, but this is non-trivial mod - if it was a simpler thing I can see just working on the back of an envelope so to speek.
That said... 
It looks like you've connected the 22n coupling cap to ground, but that won't do what you want... and I can't tell where/how the signal is flowing from the mixers to either of the places it needs to.
Going back to the schematic you're working from, and assuming everything up to the junction of the 470k mixing resistors is in place, follow the signal path in the schematic through each component and junction on the layout. For example, from the point where the two 470k mixing R's meet there should be a connection to V2 pin 7 and and a connection to the DPDT switch, but I don't see this in your rendering. For me there is no shortcut to logically stepping through each and every item in the circuit, and validating their positions on the layout (that can then be shared for others to look at  ), so that's how I'd proceed.
I'm happy to continue to try to help with whatever you post, but seeing your whole layout, and your mods of the Triwatt schematic would make that easier and probably more useful to you.
-Sieg

[idsnowdog]

To clarify the layout that I followed was the DR103 schematic from MHuss.  I added the section in purple from the Trinity TRIWATT for the OD control.  The connections I am concerned about are in black and not the connections to the tube sockets or the other pots. 

[CascoSieg]

I *think* this is what you're trying to do. I may be wrong, since I've made assumptions about some of your components, but this flow, if not the component values, should match the your schematic.
~S

[idsnowdog]

I wired it this way today.  Some of the V2 wires may be wrong.  Thanks for your help.

[CascoSieg]

You're getting there I think.
Draw the connections to ground in your layout, like I had them -  the bottoms of the two cathode Rs are ground connections, as is the ground (right) side of the OD pot, which is why it connects at the bottom of the 1k cathode R.
Move your connection from the pot left terminal back to the 22n cap like I had it. 
Not sure why your switch has two extra terminals now - I'll assume it's a miskey.
Where I had the lead labeled "to Tone Stack" connect that lead to the UNconnected terminal of the 100k slope resistor beside the two 47n tone caps. There's a 220p treble cap that should connect from there to the treble pot, and similarly, leads going to each of the mid and bass pots from those 47n caps.

I'm doing my best to help based on limited knowledge of what you've got and what you're intending - your layout implies you are diverging from the Triwatt design - why? An actual schematic of what you're intending would really help... either transcribe the Triwatt schem to ExpressSCH and modify it to match what you want to do (and you'll be happy you did this later, as you'll probably have to mod this thing to get it to sound like you want), or otherwise render YOUR schematic in complete form (e.g. draw in your edits onto the PDF), so that we don't have to guess at things, as was previously suggested by others.

[idsnowdog]

This is NOT a TRIWATT build.  This is a HIWATT DR103 build that I am trying to shoehorn the TRIWATT OD circuit into.  With the 1970s DR103 circuit half of V2 is unused.  While researching how to use the second half of the V2 Triode I found the TRIWATT layout/schematic.  The TRIWATT OD circuit was a great use for that unused triode.  The power section of the TRIWATT was also perfect for this project since I didn't want a high-wattage amplifier.  So, I built the power section of the TRIWATT on another board.

The TRIWATT schematic has similar component values but the layout is different. Since the DR103 preamp section was already built scrapping everything and starting fresh with the TRIWATT layout wasn't on the table.  Here's the complete preamp board for the DR103 layout.  The yellow line is where I spliced in the TRIWATT OD section.

Here's what I have so far.  The chassis came from a Hammond S6 that I scrapped, cut down to size, and patched.  The boards and tube sockets are also recycled from the Hammond.  I liked the TRIWATT idea of being able to switch output tubes but I didn't want the high-power KT66 option so I wired a second set of 6AQ5 sockets since 6V6 and 6AQ5 are very close substitutes. 6AQ5s are cheap and I have many of them and 6V6s aren't cheap and I have a limited supply of them.   

[Balticnoiseforge]

Could hiwatt lead give you any ideas?

https://hiwatt.org/Schematics/DR_LEAD_2InputPre.gif

[idsnowdog]

The OD circuit on that lead variant is almost identical to the one on the TRIWATT.  Too bad there isn't a layout for it.

[Balticnoiseforge]

Is the amp posted above yours? Maybe you could use a 4x1 terminal strip next to socket and simply PTP wire the extra gain stage?