Hammond S6 Line Out

[Ifudontlikebees]

Hey guys! Back with another S6 question. I've completed the chop and installed the 1/4 inch line out using the Hammond M3 and it worked! I am having an issue though. Whenever I plug it in and turn up my amp, there's a very very loud hum which prohibits me from turning my volume knob up past 2. I noticed that when I turn the potentiometer all the way down the volume cuts out completely (as it should), when I turn it up half way the buzz/hum is the loudest, and when I turn it up all the way the buzz/hum is quieter but still very loud. If anyone knows how to fix this or knows the issue please let me know! This is my first project like this and I'm very eager and excited to finish it completely and have it working correctly. Here is the link of the schematic I used and some pictures of my chop.
http://www.dairiki.org/HammondWiki/LineOutFromASpinet

[tpappano]

I must say, that looks pretty cool 8)

[Ifudontlikebees]

Thank you! Is it a ground loop? Do I need some sort of isolation transformer? If so which one would work?

[tpappano]

I would need to see an accurate wiring diagram of exactly what you did to make a reasonable guess.

[Ifudontlikebees]

Check the link in the top post, it's the exact diagram in that schematic

[tpappano]

Does the output transformer secondary winding of your S6 have a grounded center tap?

[Ifudontlikebees]

Unfortunately I don't know because I'm very new to electronics. How would I check?

[tpappano]

You need to look at the schematic for your S6, find the speakers on it, follow the speaker wires to the output transformer. Is one of the speaker wires directly connected to ground, or is the center of the transformer connected to ground?

[Ifudontlikebees]

I'm looking right now, I believe the center of the output transformer is connected to the ground. I'll attach a picture of it below so you can see it too as well as a link to the schematic incase you want to see more

https://web.archive.org/web/20080617...ics/index.html

[tpappano]

Ah ha! The ‘ground' wire of your line out circuit (the one labeled black) needs to connect to the metal *chassis* of the S6 instead of the speaker wire. So, line out ‘black' to chassis and line out ‘green' to speaker. See if that fixes the hum.

[Ifudontlikebees]

Awesome thank you! To be honest I'm confused on what you mean. How would I connect the black wire from the line out to the chassis? And I also cut out the speakers completely so I'm not quite sure how I'd connect the green wire to the speaker. Like I said I'm very new to all this, sorry and thank you!

[tpappano]

No problem 8) The “chassis” is the sheet- metal framework supporting all the tubes and other parts. Find a screw on the chassis and secure the “black” line out wire under it. This has the effect of properly “grounding” your 1/4” jack to the chassis. Now connect your “green” line out wire to *one* of the S6 wires that * used* to go to the speaker. The other S6 wire that went to the speaker should be insulated with tape, it is not needed for now. *If* this fixes the hum problem then we will change the way the 8 ohm dummy load resistor is connected for best operation.

[Ifudontlikebees]

Awesome, I'll try that today! Does it matter what wire I connect the green line out wire to? Should I connect it to the green since it is also green?

[Ifudontlikebees]

And you're saying just take the black wire and stick it under a screw on a the chassis?

[tpappano]

Yep, green to green is good, black under a chassis screw, see if that gets rid of the hum 8)