Fender Champ II input problem - input ok if conect to volpot

[wr7r]

I'm finishing up a Fender Champ II, ready to wrap it up, but I only get signal when I connect to the volume pot, not the 68K input resistor. It sounds OK, voltages are fine etc., but without anything connected to 68K input resistor.

The schematic shows the input jack with 2 connections - 1 to the volume pot (which works fine), but nothing when I connect to the 68K resistor. The jack is not original though and only has 3 connections. Please see attached schematic/picture.

Any thoughts/ideas appreciated on how I should connect the input jack to make it work correctly (aka what abt the 68K R).
[img:576:720]http://wr7r.com/images/AMP.jpg[/img]

[xtian]

Seems like you've identified an issue with the first preamp stage. Did you measure the voltages on that triode?

Check your connections!

[larsvictor]

Connecting the input signal to the volume pot is bypassing V1A and running only V1B. If the voltages on V1A are ok, check the conductance from signal input to grid (V1A pin 2) and every soldering joint in the tone control circuit.

Victor

[Structo]

The soldering does not look very good.

Reflow all the joints around V1.

If the joint is not smooth and shiny, it is suspect.

[wr7r]

thanks the input - I will double check the soldering today. Originally I thought it had something to do with the OEM jack, which according to the schematic has 4 connections(?!) and my replacement has 3. Nothing I put at the junctiona of that 1 meg and 68K resistor causes any sound....so will check voltages there..

thanks!