PL 4000 issues and solutions

[marcok]

1) serial number
2) new connectors
3) Phono 2 Riaa inverter circuits
4) wrong pcb on volume pot ( this causes bad contacts and shorts between mother board and front board )
Fixed with an isolation paint for pcb
5) internal wiring of new connectors

I hope it could be helpfull .

Ciao
Marco

 

[WOPL Sniffer]

Did your "GURU" do the work?

 

[marcok]

No , me !
My guru made the recap , since it's necessary to have a desoldering unit not to destroy the pcb tracks of the boards.
( they are very fragile ) .
Furthermore he helped me to understand how to fix bad conctacts between mother board and front panel
and how to clean the switches .
I changed all the RCA s , I added the RIAA inverter on phono 2 and an attenuator on Aux outputs to drive
PL 400 .
I made these modifications on two units .
Ciao
Marco

 

[marcok]

It must be noticed that that problem of the pot was known from Phase Linear .
I have the first release of service manual of PL 4000 , where it's written :
"In case of bad contacts check the connector expecially near volume pot ."
In the second realease (ncomplete ) ,the only that you can find in the web ,there's no evidence of this issue ,
but they speak about a wired version of the connections between mother board and front panel board .
( never seen ). At the the begining you think about the switches , but moving them you push
the male connector located on front board . It took me and my guru much time to understand this issue .
Another critical point is the connection between the peak unlimiter board and the mother board ,
due to the little connector put in the center of this board . Infact they used a piece of sponge ,
located on top cover , to lock it .

Ciao
Marco