grouding - the horse isn't dead yet

[mikepukmel]

Hi All,
I hope it doesn't look like Im beading a dead horse, I think it is still kicking. Anyway, old cliche's aside, id like to get into the finer details of what a better grounding scheme would look like, in practice for this amp. Taking all of your awesome suggestions, and detailed posts, I get the main ideas:

A given tube is fed from a node in the power supply at a filter cap.
So, the idea is to run the grounds coming off that tube's cathode cap/resistor, to the other end of the filter cap that feeds power to that tube, then from that junction at the ground side of that filter cap, run a ground wire to the star ground.

I can get far, but not perfect with this amp, due to the eyelet/turret board's design:



I have 4 points marked 0, 1, 2, 3 where wires are run to ground from the board.

I can easily get point 3 wired up to the ground side of the last filter cap, and I do have wiring in place for that, then run a wire back to the star from there.

Point 2 is tough, since it has two cathode signals tied to the same turret, and I don't have any way to add another turret to this board.

Point 1 is easy since I don't have tremolo (thank God and Leo for small favors!). I can just run this ground up to where point 3 is run.

Point 0 is easy as well, since I don't have tremolo. The phase inverter is the only tube fed from the second filter cap.

If I were going to build another Deluxe, or similar AB763 circuit, would it be worth it to have 2 more turrets installed, so I could separately ground the cathode wiring to their respective filter caps?




Thanks
MP

[nosaj]

Hi All,
I hope it doesn't look like Im beading a dead horse, I think it is still kicking. Anyway, old cliche's aside, id like to get into the finer details of what a better grounding scheme would look like, in practice for this amp. Taking all of your awesome suggestions, and detailed posts, I get the main ideas:

A given tube is fed from a node in the power supply at a filter cap.
So, the idea is to run the grounds coming off that tube's cathode cap/resistor, to the other end of the filter cap that feeds power to that tube, then from that junction at the ground side of that filter cap, run a ground wire to the star ground.

I can get far, but not perfect with this amp, due to the eyelet/turret board's design:

[ATTACH=CONFIG]47631[/ATTACH]

I have 4 points marked 0, 1, 2, 3 where wires are run to ground from the board.

I can easily get point 3 wired up to the ground side of the last filter cap, and I do have wiring in place for that, then run a wire back to the star from there.

Point 2 is tough, since it has two cathode signals tied to the same turret, and I don't have any way to add another turret to this board.

Point 1 is easy since I don't have tremolo (thank God and Leo for small favors!). I can just run this ground up to where point 3 is run.

Point 0 is easy as well, since I don't have tremolo. The phase inverter is the only tube fed from the second filter cap.

If I were going to build another Deluxe, or similar AB763 circuit, would it be worth it to have 2 more turrets installed, so I could separately ground the cathode wiring to their respective filter caps?




Thanks
MP

Some people will mount the pots backawards on the chassis then take a thick copper buss to solder against the back of the pots. Fender I believe used a copper sheet in there I believe.
Maybe someone will elaborate on the Power Supply ground versus the Signal ground and the need to separate it. For your power supply ground star connection are you using a solder tab with a bolt or using a solder gun to solder directly to the chassis?

nosaj

[soundmasterg]

Some people will mount the pots backawards on the chassis then take a thick copper buss to solder against the back of the pots. Fender I believe used a copper sheet in there I believe.
Maybe someone will elaborate on the Power Supply ground versus the Signal ground and the need to separate it. For your power supply ground star connection are you using a solder tab with a bolt or using a solder gun to solder directly to the chassis?

nosaj

@nosaj, Rather than grounding to the back of the pots, if you wanted to use a buss there it would be better to run a ground buss between the ground points on the pot terminals but not to the case of the pots, and then you could ground to that buss off your board and then one end of that buss to your chassis ground point. Grounding to the pot cases ends up being many chassis ground points, which isn't any advantage over what Fender did with the brass ground plate.

@mikepukmel, you're right in that #2 has quite a few things attached to that turret....the reverb driver and recovery cathode grounds. If you wrap the ground wire first around the turret properly, then wrap the leads for your other parts properly, the solder after all are attached, you should be able to fit it all on there. Pre-tin and twist the wire first before wrapping it around the turret and it will make it easier.

Greg

[mozz]

HV ct, fil ct, pwr in gnd, filter caps neg. All together fairly close to PT. Every other gnd to buss bar, either on the pots or across the turret board. Preamp gnds together and to input jack gnds or back of pots. Whatever is close and short. I never get more than a few mv hum. I love those old octal sockets with 4 gnd connections.

[mikepukmel]

HV ct, fil ct, pwr in gnd, filter caps neg. All together fairly close to PT. Every other gnd to buss bar, either on the pots or across the turret board. Preamp gnds together and to input jack gnds or back of pots. Whatever is close and short. I never get more than a few mv hum. I love those old octal sockets with 4 gnd connections.

Almost done. Got everything wired except a few ground wires, and the input jack shielded wiring.