Jerry's "Gonna Rebuild me PLWO 1000" thread

[Gibsonian]

What is the name on the amp tag (i.e. who originally built her?)

 

[jbeckva]

Dart?

 

[jbeckva]

So I'm getting close now. Question that I'd still like to discuss is the use of a 3 prong AC main that I would ground to the chassis. I've heard some arguments pro and con, but what specifically would be the problem doing this?

Any takers?

 

[laatsch55]

Maybe increased noise due to ground looping and the board floating above chassias ground by 2.7 ohms. Ain't gonna hurt anything by doing it and you might be quieter. You can always change it back if you don't like it. Mark had a few good posts on that grounding thing, can't find it. Jer , could you start a White Oak section and any time we have some Phase/White Oak specific posts we want to refer too we can copy them to that section so they're not so hard to find. Like Joe's grounding scheme, the explaination for each improvement he does, etc??

 

[Skratch]

Jerry, Where are you going to be coming in with your 110 AC. Are you going to move it to the power tranny side. Also I think you should have only 1 earth ground on your system, usually the preamp

 

[jbeckva]

Yeah, I'm going to relocate the main fuse over to the other side, and come in that way. Lee - where's that 2.7 ohms at? I see that wire that comes down from the caps and hits the chassis via those center points... is it still lifted from the chassis with a resistor I can't see?

Two prongs it'll be.. sounds like...

 

[Skratch]

Jerry The 2.7 ohm resistor is R2 on the white oak board input section. There is no resistors on the chassis grounds

 

[Skratch]

Men, What is the size of the faceplate on a 700 series 1

 

[jbeckva]

Jerry The 2.7 ohm resistor is R2 on the white oak board input section. There is no resistors on the chassis grounds

Ah, now that's puzzling to me. If I tie the actual input signal ground to the star ground AND tie the driver board's ground to the same star ground, then don't I defeat the ground lift completely with R2? I thought that is how it was supposed to go?

So that I have it clear as mud, where should the following connections go as far as grounding?

1. The main output grounds
2. The input grounds i.e. right at the back of the RCA's and at the shield inputs on the driver board
3. The driver board grounds i.e. pins #8 if you go left to right on each 10 pin connector/eyelets

 

[jbeckva]

Men, What is the size of the faceplate on a 700 series 1

I show 19" x 7 1/2 "

 

[Skratch]

Jerry, The grounding bar or star ground should have the speaker out negatives, the grounds in the middle of the 3 terminal strips, the ground for the inputs and I have seen grounds for the driver board connected to the input ground or back to the bus or star ground. On DC speaker protection you can go to the middle of the 3 terminal lug or star ground. The driver board grounds are the 8th from the left on the 10 terminal strip. Do you have the 3 jumpers on the back of the white oak board

 

[mlucitt]

As Lee mentioned, Joe updated the input grounds on the White Oak Audio Board so they are balanced and if you ground the input shields to the star ground you defeat what Joe has done. There is also a school of thought that the output grounds (Star ground) should not be tied to the input grounds due to the difference of AC and DC potential between the input signal and the output signal.

So I like to take the input pairs straight to the board on a short run, or to the pots on a PL 700 and then to the board. The board is grounded on terminal 5R and this wire should go to the Star ground. This preserves the 2.7 Ohm gound lift on the inputs.

The DC Protect board, LED/light board, signal outputs, and the wire grounding the chassis should all be tied to the Star ground. In my opinion.

 

[laatsch55]

A 700B faceplate are the exact same dimensions as a 400.

5L, 5R are the board grounds, they go to the star ground. Mark is pretty much right on the rest of it.
Jer, I don't think I went separate +/- feeds to both sides of the board so there should be jumpers on the back of the board.

 

[mlucitt]

Joe and I use the jumpers on the back of the White Oak Audio board, Lee has to be contrary, sometimes, when it suits him. It's what we like about him.

 

[laatsch55]

Well, I suppose.

 

[Gepetto]

That is why both options were provided Mark, as opinions clearly differ on things like this.

That is one of the best parts about vintage audio tweaking, many opinions and positions are shared. This forum is the best I have found for discussing audio with none of the usual flaming that happens on other forums.

 

[laatsch55]

Yep Joe, that's what we love about it, that and it's just kinda quaint, and threadcrapping is encouraged, and........,well, you know.

 

[Skratch]

Men On a white oak board do you disconnect all grounding from the star or bus to the inputs and just connect the board pin 5 to the star or bus. and from the inputs just the 2 wires. Also is the 700 Series 1 and the 700B faceplates the same size? Jerry came up with 7 1/2 X 19 on series 1

 

[laatsch55]

B and series I plates are different sizes. I have both here. I will measure vto confirm.

 

[laatsch55]

Series I---19 X 7.5 700B---18-15/16-X-7.00