Troubleshooting an humming WOPL : need help!

[Coldsmoke]

Based on what I see here, you may not have a ground to the control board.

It appears that the original jumper between the speaker terminal negative and the copper input plate has been correctly removed. There seems to be a white wire connection between that same copper plate and pin 5R of the control board. If this visual is correct, then my recommendation is to remove this white wire between the copper plate and pin 5R and replace it with a white 20AWG wire connection between 5L and the copper bus bar between the 2 caps.

I cannot tell for sure but this is what it looks like.

A couple of close up shots around the input plate to right side of control board would help, as well as a closeup of all the wire connections to the bottom edge of the control board.

Thanks for your tip Gepetto.
I already put in place a wire (the red one on the copper bus) between 5L and the copper bus, following Laatsch advise. I suppose I can just remove the white one to 5R then?
I'll supply you quickly with better shots.

 

[Gepetto]

Based on what I see here, you may not have a ground to the control board.

It appears that the original jumper between the speaker terminal negative and the copper input plate has been correctly removed. There seems to be a white wire connection between that same copper plate and pin 5R of the control board. If this visual is correct, then my recommendation is to remove this white wire between the copper plate and pin 5R and replace it with a white 20AWG wire connection between 5L and the copper bus bar between the 2 caps.

I cannot tell for sure but this is what it looks like.

A couple of close up shots around the input plate to right side of control board would help, as well as a closeup of all the wire connections to the bottom edge of the control board.

Summary of what ground scheme you should have:

20AWG white wire connection from cap copper bus bar to pin 5L (new wire)
22AWG connection from left input RCA jack floating copper plate to pin 2L (existing wire)
22AWG connection from right input RCA jack floating copper plate to pin 2R (existing wire)

18AWG white wire connection from cap copper bus bar to left channel black speaker binding post (existing wire).
18AWG white wire connection from cap copper bus bar to right channel black speaker binding post (existing wire).

22AWG white wire connection from cap copper bus bar to chassis ground in one place only (this is usually the middle leg of one of the 3 terminal solder lug strips in the middle of each channel)

NO safety ground connection from AC plug to chassis ground. PL always used a 2 wire connection.

That is the description in words of the optimum ground scheme for the PL400 amp. Hope it helps.

 

[Gepetto]

Thanks for your tip Gepetto.
I already put in place a wire (the red one on the copper bus) between 5L and the copper bus, following Laatsch advise. I suppose I can just remove the white one to 5R then?
I'll supply you quickly with better shots.

Yes, that wire creates a ground loop which is undesireable.

 

[laatsch55]

You're on the ball this mornin Joe!! Snowed in??

 

[Coldsmoke]

Good catch Joe.....


We need a photo of the trace side of the control board now...we are trying to determine whether the control board is grounded to Star ground...

Here we are :

 

[laatsch55]

Yes, that wire creates a ground loop which is undesireable.

Just plain sucks too.....

 

[Coldsmoke]

So, if I sum up :

- I put in place my 0.022uF 400VDC caps (it's the closest value I could find)
- I cut the grren wire from the power cord
- I remove the white wire from 5R
- I cross my fingers and voilà

?

 

[Gepetto]

So, if I sum up :

- I put in place my 0.022uF 400VDC caps (it's the closest value I could find)
- I cut the grren wire from the power cord
- I remove the white wire from 5R
- I cross my fingers and voilà

?

I assume you mean 0.22uF caps, not 22uF caps...

 

[Coldsmoke]

I assume you mean 0.22uF caps, not 22uF caps...

yes...

 

[Gepetto]

You're on the ball this mornin Joe!! Snowed in??

And then some Lee. Feels like Siberia here in New England.

 

[Coldsmoke]

BTW, could you give me some good references for speakers and RCA inputs for a replacement....?

 

[laatsch55]

The weather channel paid a lot of attention to your situation last night. That's a lot of f%&^&^%$ snow Buddy...

 

[Gepetto]

Here we are :

View attachment 19134 View attachment 19135 View attachment 19136 View attachment 19137

Assuming that the red wire to 5L is a ground connection to the copper cap bus, then other connections all appear correct except the pin 5R to floating copper plate connection which you are removing...

 

[laatsch55]

BTW, could you give me some good references for speakers and RCA inputs for a replacement....?

Mouser part numbers??

 

[Coldsmoke]

I assume you mean 0.22uF caps, not 22uF caps...

Hew... you mean 0.022 and not 0.22 right? (this is getting confusing here :s)

 

[Coldsmoke]

Assuming that the red wire to 5L is a ground connection to the copper cap bus, then other connections all appear correct except the pin 5R to floating copper plate connection which you are removing...

Wonderfull

 

[Coldsmoke]

Mouser part numbers??

Would be very appreciable

 

[laatsch55]

Mouser


Binding post white---530-111-0101-1
Binding post black---530-111-0103-1
Binding post red------530-111-0102-1
Switchcraft RCA jacks----502-3501FRX

 

[Gepetto]

Hew... you mean 0.022 and not 0.22 right? (this is getting confusing here :s)

Those will work as well. The value is not all that critical (as long as it is not 22uF ), the voltage rating is for this location.

 

[Coldsmoke]

Ok, I think I have enough to do here : ) thanks a lot again for your very valuable advises.

Do you - by chance - know a little about PL 2000 pre-amp?
If so, I could come up with a couple of question later this week