Fender Champ IIClone - how to substitute OEM Jack P/N 011028

[wr7r]

I have finished building a clone Fender Champ II - it works but only by sidestepping the normal input and jacking into the 250 pFd cap. I'm trying to find one of these 4 pin jacks but was wondering if there was another way to handle this with a standard Switchcraft? The amp seems to work OK, still testing the tone (see link to video below). Any ideas much appreciated.

[img:590:479]http://www.wr7r.com/pics/champ.jpg[/img]

http://youtu.be/uicz5-gUDIc

[martin manning]

Looks like the idea is to ground the input to the second stage using an isolated contact when no guitar is plugged in, probably because its less noisy. You could use a Switchcraft type 12A (standard type of input jack) and forget about the lead going to the top of the treble pot, or use a type 13E and duplicate the circuit as shown. What have you got in there now? You should be able to get it to work connecting directly to the input of the first stage.

[wr7r]

I have 12A in their right now but something is not right. I can conect the input directly to the pin volume pot and have decent sound, but my V1a voltages are way off. My V1a plate voltage is around 300 vdc. I dont get anything when I connect to the input of the 68K R, so I thik I have a V1a problem as well, but I figured theFender 011028 was a standard input jack.

[martin manning]

V1A is likely the problem. Plate voltage at or near supply voltage means little or no current is flowing through it and it won't pass any signal. Check the wiring and solder joints.

[Leo_Gnardo]

Also if your V1A cathode resistor isn't connected, or is open-circuit or much greater than 1500 ohms value (like 150K), that would let the plate swing up to 300V and no amplification either.