Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thread

[laatsch55]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

I would post it here too. If this is going to be the go-to place to solve problems and help with the boards in general.

 

[mlucitt]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

Lee, I see that you are already at AudioKarma. Since we want to spread this out a bit I will post at Audio Asylum. Any issues with that?

 

[laatsch55]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

None at all Mark.

 

[mlucitt]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

I think I got Joe's transistor orientation schema figured out. Where the type of the transistor is labeled on the board, the rounded end goes there...

Basically for the TIS devices he provided for Q1 and Q2 and the 2N and MPS devices he provided for Q3 and Q4 the "flat" sides all face down when looking at the front of the board. As in your pictures...

The exception are the regulators and they "face" up.

 

[laatsch55]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

Correct, all flat sides Q1-Q4 all face toward the bottom of the board.

 

[laatsch55]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

Mark, there was a mistake I made on R2L, and R2R The 2.7 ohm should be R2R, the 56 ohm R2L.

 

[mlucitt]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

I was following Joe's BOM so the 2.7 went into R2R...

He said he made a mistake on the screen printing, did you find it?

 

[mlucitt]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

Ha, I just looked at your completed board and I did the same thing you did. I put Joe's aluminum heatsinks on the pair of Q7 transistors and reused the four old heatsinks for the Q5's and the Q10's. How did you put the aluminum heatsinks on the transistor cans? I used a 5/16" nut driver to drive them on, with the heatsink laying upside down on the bench.

 

[laatsch55]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

On the really big ones, I had those in stock. Took a screwedriver as a wedge, they will have to be desoldered if they ever come off. The "waldo" was C31 on the right side.

 

[laatsch55]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

Getting some work done on the 700 tonight. Got the bracket for the DC PCB's done and the PCB's mounted . found some really cool grommets in my parts bag. Used Nylocs this time.

 

[mlucitt]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

C31 matched on the schematic, I went right over it because there is no bypass cap C31 on the PL700B.

I'm looking at the wiring to the board. Are you using a "star" grounding topology on Jerry's amp? I'm trying to figure out how to use the ground wire (Connection 6 on the old board) and each of Joe's grounds (Connection 5L and 5R on the new board). Is his abbreviation "CH" for chassis? This could be confused for channel... His schematic is opposite to the PL schematic as far as the chassis ground and earth ground are concerned.

Check my thinking here - the two channel grounds, 5R and 5L are tied together to prevent ground loops. This is the reference ground for the board and should be connected to the enclosure (PL connection 6) which is earthed by the power cable. The shield ground on the input to the board on connection 2R and 2L should also be attached to the enclosure. For the output of the amp there should not be a connection between the output ground and the input ground. The output ground connection should go back to the filter cap common.

Thoughts?

 

[laatsch55]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

Post a pic Mark, ya got me confused. I was just getting into that on mine.

 

[laatsch55]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

I believe CH is chassis ground, yes.

 

[laatsch55]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

The "star" ground on the PL's is the bus bar connecting the two big caps together. This is then earthed to the chassis by the small white wires going to the solder tabs in the middle of each channels outputs.

 

[laatsch55]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

I e-mailed Joe, he should be here in a bit.

 

[laatsch55]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

C31 is C20 on the left channel.

 

[Gepetto]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

All Phase Linear boards that I have run across have 2 different grounds entering the board near the bottom. Phase did not use a different ground symbol on their schematics which makes it confusing. There is a signal ground and a chassis ground. The signal ground is GENERALLY a black wire that originates from the ground connecting the 2 RCA input jacks, this also connects to the chassis near the RCA jacks. In the PL400 this ground is GENERALLY delivered to the preamp board using twisted pair wiring. In the PL700B it is GENERALLY via shielded coax cable. All the sensitive low level analog signal grounds on the board are connected to this ground node. These ground nodes are kept separate on the board one for the right and one for the left channel. The signal ground comes in via pin 2 on the bottom edge of each channel at the bottom of the PCB. Connections to this ground are: R3, C6, Q3-C for each channel.
The other ground is chassis ground and GENERALLY is connected to the PCB via a white wire that originates at the same chassis connection near the RCA jack connection. On Phase Linear boards both channels are connected to this same ground wire, the traces are combined into one for this ground type. The power bypass caps C3 on each channel of the PCB are connected to this ground as well as C10 on each channel as well as the cathode of D11 and anode of D12 (these are the diode clamps used in the output current limit protection circuitry). There is a resistive connection between signal ground and chassis ground on the PCB. The left channel uses a 56 ohm resistor to connect these 2 grounds and the right channel uses a 2.7 ohm resistor. I don't know why they are of a different value but they consistently are these values. The speaker returns GENERALLY go directly from the binding post negative back to the POWER ground node that is the copper bus bar between the 2 large bulk caps mounted on the transformer. There is GENERALLY a connection from this copper bus bar to the chassis ground via a small 3 lug terminal strip mounted to the aluminum chassis.
Phase Linear really does not have a true single point ground in any configurations I have seen. The aluminum chassis serves as this single point ground.

Hope this helps out rather than confuse. Ask any questions that you have. Thx.

 

[Gepetto]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

I am in the lab tonight and will periodically check this thread for any additional questions.

 

[laatsch55]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

Thanks Joe, that helps a lot. On YOUR schematic there are references to CH_GND-R, does that refer to CHANNEL ground or CHASSIS ground?

 

[Gepetto]

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

It is a good idea to mark your Phase Linear schematics with a C next to the ground symbol for the grounds that connect to C3, C23, C10, D11-C, D12-A to denote chassis ground. Leave the other grounds on the schematic unmarked. This will help you distinguish between the 2 different runs.

I forgot to mention that the chassis ground connection to the PCB comes in on pin 5

The White Oak board maintains these same ground separation relationships exactly.