Building a Pearl 2

[6L6]

PhopsonNY -

Look at the Pearl PCBs, there is a pad on each just above C12, connect that to the ground stud.

What's connected to the ground stud now?

 

[Russellc]

If it's particularly ugly, that's the point! Photo as is!!

Oh I will...

Russellc

 

[PhopsonNY]

6L6...

That is how it is connected... the yellow wires come from those ground points near C12 on the RIAA boards to the stud.
The third yellow wire comes from the chassis connection.

PhopsonNY -

Look at the Pearl PCBs, there is a pad on each just above C12, connect that to the ground stud.

What's connected to the ground stud now?

 

[PhopsonNY]

Found Hum Source

Per post by Berd #2746 in :

Berd's Hum update

I the hum disappears when the phono input from my player is disconnected from the pe2. So I guess this is a problem with my RP6 output cable.

Any thoughts?

 

[6c4c]

Check connection between tonearm body and GND post on Pearl 2.

 

[PhopsonNY]

Thanks 6c4c...

The rp6 does not have a dedicated grounding wire.

The ground is through the left channel signal ground.

But this might be the issue.
Looking into it.

Check connection between tonearm body and GND post on Pearl 2.

 

[Russellc]

Photo?

Here's the old pic from way back in the beginning of this thread:


http://www.diyaudio.com/forums/pass-labs/204336-building-pearl-2-a-3.html#post3640795

Favorable angle, "facplate" is the piece of aluminum I spoke of, leaning up against chassis, STILL not attached.

Here it is in a dusty hidden corner...

 

[6L6]

It's perfect! You'll never want to place it anywhere where it could be seen! Far far away from the phono box and therefore quiet.

 

[6L6]

The rp6 does not have a dedicated grounding wire.

The ground is through the left channel signal ground.

Yes, however completely inconsequential. The circuit needs to be grounded together and to chassis through that point.

 

[joho]

Hi Gents,

I'm building a Pearl 2 currently and it's looking ok but sometimes Q1 is broken immidiately after power on. Two times since the start of this project. The collector/ emittor is infinite. Maybe the loading current of C6 is the problem or I use bad quality ZTX 450's. Any idea's? or Modifications?

 

[6L6]

There's only 4 volts or so across that transistor... Look for other errors. Or perhaps as you suspect you have a bad batch of ZTX...

 

[joho]

It's a strange problem isn't it?...since this afternoon I've fitted a good old BC550 ... see what happens the coming period.
I had also some trouble with gain difference between left and right hand. Around 6db difference. First stages are equal but the problem is in the second stage. After replacing Q4 the gain difference is 3db now. Is Q4,Q5 critical regarding the gain? or just a little tweaking with the feedback resistor value?

 

[PhopsonNY]

Yes, however completely inconsequential. The circuit needs to be grounded together and to chassis through that point.

Yeah... Thanks 6L6.
All grounding is correct to that point.
I suspect it is the cable not the grounding... Regas seem prone to this.

Full Preamp volume range...140
Normal listening level exacr2 MM...35 to 42
Hmm evident ... 80

 

[6L6]

Same grounding scheme still applies.

Get the PCB's ground center to the ground post, which is then also chassis, that will tie both PCBs together and hopefully eliminate a large potential difference between them and make up for the single ground point that the Rega arms use.

 

[PhopsonNY]

Perhaps I am misunderstanding.
Both RIAA boards are tied to the grounding post from the center points and the chassis also.
The hum is even evident when the power supply umbilical is disconnected.

Could a bad CAP or solder joint cause this?

 

[6L6]

That's a ground loop.

What jacks are connected to the chassis? (I.E., not insulated?)

 

[PhopsonNY]

The RCA sockets negatives all have continuity with the chassis as I thought they should have.
The chassis screw provides this?

 

[6L6]

There is your problem.

All jacks (power umbilical and RCA) need to be isolated from the chassis.

The ground post is the only point that touches the chassis.

 

[PhopsonNY]

Progress... great, but I should not connect from the center point of the RIAA boards to the ground post?

Maybe I missed somthing... per your post 33?

 

[6L6]

(click photo if it's all smushed because of the forum formatting)

You can make the ground lug connect to chassis at the post itself, or isolate and have a separate screw as shown. Regardless, it's the only point to touch the chassis.

Note in this drawing no jacks touch the chassis.