David's Phase Linear 700B Thread

[laatsch55]

Less than the original, thanks to you...

 

[jbeckva]

Looking good Jer. Lots of wiring in there ehh?

Yep a little bit...

But ok now.. here's where we should have another one of those dreaded grounding discussions.. heheh... Let me show part of your diagram Joe ...



So far, what I see is

1. The shields for the cables TO the pots... attached to the ground plate (check. got it...)
2. The "s" (sleeve?) parts of each RCA jack... also attached to the ground plate (by way of the "nuts" making direct contact to the plate... check.. got it..)
3. The two connections between the sleeves of the jacks and the plate, going off the picture and onto the WO boards L and R signal returns.. (got it... *sort of*.. )
4. The tip/signal lines of the jacks coming in and wired to the switch.. which either bypasses or switches "in" the cap coupling... then from the switch, off to the pots as the center/signal conductors. (got that too)

Now.. hmmmm.... the two cables going to the pots are (should be) going to be wired "across" the pot's resistance (fixed 100K). The center/hot signal conductor on one outer lug of the pot, the shield on the other.. AND ... on the same side as the shield, the shield conductor for the OTHER cable which leads eventually back to the WO board. On that same "OTHER" cable, the center/hot signal is wired to the center/wiper lug of the pot.. So that... the signal leading back to the WO board's inputs "taps" off of the pot like a normal volume control would be..

Now here's the kicker.. the big question... IF I already have the shields that are coming down from the copper plate to the WO board's signal returns (2R and 2L), what do I do with the shield/ground/return line that is part of the cables coming FROM the pots? Why wouldn't I NOT connect the two lines from the plate to the WO board, and instead use the shield/ground/return lines included with the cables that go between the pots and the inputs on the board? Visualize .... from 2R/2L, and up through that cable to the pot.. we have the shields connected. At the pot, the shields coming from the cables that are connected to 2R/2L on the other end, are also connected to the shields for the cables going from the pot and over to the RCA's... and there.. they both terminate right on the grounding plate.

Why would I want to run single wires directly from the ground plate to 2R/2L?


(yep, you knew this was coming.. hehehe.... )

 

[Gepetto]

Those wires to 2L/R indicate the shields Jer. Eventually I will be putting the pots into the schematic but I was running out of room and that was a major reorder.


Let me put it in words:


RCA Shell to the copper plate in 2 places. (I usually put a small solder attachment in addition to the nut to eliminate intermittents that comes from the eventual mechanical loosening of the RCA nuts)

Origin of both shields to the copper plate at the RCA jack end of wires.

Shield from end of first leg of cable run to the L/R Pot ground tab on the pot.

Shield from start of second leg of cable run to the L/R Pot ground tab as well (this essentially makes the shield into a continuous electrical run)

Shield from end of second leg of cable run to connection pad 2L/R on the White Oak PL14_20 board.


Signal run is more obvious I think.

Clear?

Basically the shield of the shielded cable is the ground run all the way from the copper plate down to the WO board.

 

[jbeckva]

Yessir... Originate the ground from the sleeve on the RCA end, and the shield from the pot on the WO end.. pretty much!

"Combing" this rats-nest a lil and getting the DCP wired in... It's getting there!

 

[Gepetto]

I will be done the Jer special schematic update shortly.

 

[Gepetto]

Updated PL700B Grounding Schematic with Front Panel Pots added.

Hope this clarifies it fully Jer.
View attachment PL700 Grounding.pdf

 

[jbeckva]

Hope this clarifies it fully Jer.
View attachment 9550

Uh huh sure does, Joe! I couldn't get past those two connections that looked like two extra wires runnin...

Ok.. done for tonight. Repaired the WO board, DCP's just about in. Tomorrow we assemble the bias brackets (shout out to to NavLinear - those are real wire savers!!), wire in the WO board, then we fuse it and "go"!

 

[Phase Linear Phanatic]

Less than the original, thanks to you...

And if I had wanted to get super picky; I would have requested all new wires be ran too? The original wiring in there wasn't the best I have seen. Heck, I would have supplied you with what you needed too? I have THHN or MTW of any size or color. Shielded analog? Name it. Had a guy at work today botching up some soldering work. Had to give a lesson of how to intertwine and heat shrink so no strands poked through the shrink. No solder blobs! I promise! LOl! This panel was for Miller-Coors brewery. Today I worked on Monsanto panels and finished up Campbell's. Tired.

If there are any other upgrades you might suggest Jer, while the amp is in your care, please let me know. I will probably give the go ahead. But sounds like progress so far!

 

[jbeckva]

Uh oh...



So far so good. Bias came right in at 415. No HUM that I can hear, and it was shaking stuff off of my shelves. Going to let it burn in for a few days, David. Might do some ground rerouting but we'll see.

 

[laatsch55]

Where's a pic of the amp Jer??

 

[laatsch55]

With the bias at 415, do you have 15 ohmers in R38,R39???

 

[jbeckva]

Where's a pic of the amp Jer??

If it was a snake.... you blind melon

 

[jbeckva]

With the bias at 415, do you have 15 ohmers in R38,R39???

Nope.. whatever you put in on the DCP heheh.

Sounds good.. got brain in a fishtank going right now. clear.. smooth.. like a WOPL should sound!

 

[laatsch55]

I still don't see a front panel shot of a 700B.

 

[jbeckva]

I still don't see a front panel shot of a 700B.

It's on it's butt. You will but ya see those other two PL's in it's "spot"?? 35 lbs and 60 lbs???

Prolly later.. we be jammin'... dropping it "subsonic"... got me coffee vibratin.. woohooo

 

[laatsch55]

Ah, very true, but have you vibrated the eyeballs yet??????????

 

[jbeckva]

Ah, very true, but have you vibrated the eyeballs yet??????????

Got both David's 700B and my own 700 going. I can't go past half power without crying for mama...

Did I ever tell you about when I first hooked up SN 1?? I had to drive a deck screw into the side of the left D9 because the cabinet was shaking itself apart.

There needs to be a mandatory hearing safety course that comes with a WOPL hehehe.

 

[laatsch55]

I believe I am backing out nails out of my floor joists....

 

[Phase Linear Phanatic]

I believe I am backing out nails out of my floor joists....

Just what I wanted to hear. Wonderful. If re-running the AC wire path is in your time-process.....have at it! This will make one powerful low end amp. Once you send it back Jer, I will send you my other 700B that I use bi-amped for my high end! You can WOA that all the way! It's even more cosmetically beautiful than the first one? So can I consider this one a WOPL 1000 yet?

 

[laatsch55]

Depends on the transformer voltage. They varied from the factory, but to get to 500 a side rail voltage needs to be greater than 83volts DC+/-.