Metropoulos Forum

When I converted my 2204 to a non-MV, I really didn't want to hack up the original faceplate, so I internally jumpered the two channels by simply connecting the V1 grids together.
I suspect that doing this does not give the correct input impedance. With the Channel II volume on 7-8, Channel I on zero, the input signal is rather weak. Channel I is pretty close on its own.
Anyone have any thoughts on this, or has anyone internally jumpered one of these with more success? I'm really loathe to cut up my faceplate for four inputs, and repros don't locate the switches quite right for the later rocker switches, although I may have to go that route if I can't find a better solution.
Hey George, I had to crack up a little, when I put this PTP board in I spent a lot of time comparing the schematic you sent to a 2204 schem trying to get the switch/choke wiring right. Never did turn your wire-color-to-this-spot sheet over to see that you had another diagram with the parts labelled and had made some notes on it for those same wires from the switches/chokes!! Just discovered it tonight.

Hey Flames1950, are your inputs wired as HI/LOW sensitivity or just the HI Sens for each channel?

When I jump channels internally, I use one set of input jacks (HI/LOW). Mount the 68K input resistors on the jacks. And run a piece of coax to the V1 socket, with the grids connected.
This is the quietest way I found for bridged channels. Way quieter (hum and noise wise) than a patch cord between the jacks.

George

I'm sure I wired them as a high/low pair. I gotta make sure tonight.
I left the 68K's on the board, haven't really noticed any hum problems. Just the usual hiss of a Marshall on eight. It's music to your ears, ya know.

Well, I did have the jacks wired wrong, but it was in such a way that the high input worked fine, but the low input would have actually gone totally open if I'd used it. Yeah, like I use that a lot.
To be honest, I never jumper the channels anyway, I use Ch. I by itself with a Gibson, Ch. II by itself with a Fender. I think it will be just as easy to wire each jack as the high input for each channel. The 68K's are all on the board, even the unused ones, I'll run to them so they're parallel and add a 1M resistor to ground. Then if problems still exist at least I can troubleshoot the channels as individual units.

So 'fess up, George. What's with the "velvet", favorite stage shirt? Ruffly collar and sleeves on nice velvet?