PL 4000 Restoration

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Wayne G.

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Audio buff since the 70s
#1
Finally got my PL4000 back. It had developed a hum even with no input and the sound was not that good. I sent it to Circle Stereo in Texas and he replaced ALL the capacitors and re-soldered all the Motherboard socket joints (daughter card holders). He also replaced all the rear jacks with
jacks mounted to the rear panel instead of the mother board. Not many are willing to work on these but is familiar with the units as he has done a few of these.
 

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gadget73

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#4
The back mounted jacks look nice. The stock ones are pretty crappy. I stole the rear output jacks on my friend's to replace the broken phono input jack. He's not using it 4 channel but he does have a turntable. I also had to re-flow all of the motherboard connections to make it go. Worked OK after that.
 
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Wayne G.

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#5
MarkWComer said:
Was the job expensive?
Click to expand...
YES, but to replace those jacks you have to "Jumper wire" the new ones to the mother board so that's twice the number of solder joints per jack. He also takes hold of the front panel with it hooked up shakes the hold thing holding the front to determine if there are broken solder joints and touches them all up till NO noise at all. Some how he was able to tighten all the controls so the feel is really good. With ALL new caps it sounds wonderful.
 
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Wayne G.

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#6
BubbaH said:
Is that quad?
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Yes and No. It is "SQ" simulated quad, however it does have outputs for a rear channel amp. and the joystick will control the position of the sound. So although quad is not "Discreet" and will not decode quad records. PS never got into quad myself so I have never tested the rear outputs.
 
MarkWComer

MarkWComer

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#7
Wayne G. said:
Yes and No. It is "SQ" simulated quad, however it does have outputs for a rear channel amp. and the joystick will control the position of the sound. So although quad is not "Discreet" and will not decode quad records. PS never got into quad myself so I have never tested the rear outputs.
Click to expand...
The Carver C4000 had the same circuit and a built-in 40W amp for the rear channels. The 4000T just had outputs and no internal amp. Essentially the same, but with the "Series II" PL look and "Sonic Holography."

I never went "quad" either, I saw too much "VHS/Beta" arguments over which was best and was waiting for all that to die down. Quad died instead of the debate...
 
marcok

marcok

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#8
Hi all ,
I have restored two PL 4000s in the same way and now they work well.
Fortunately I did not found issues in the mother boards .
In one system I use the quad mode with normal stereo sources using a class T power amp.
You can obtain an " ambience effect ".
C4000 is different , because it has a real delay time unit ( based on Reticon Sad 4096 with 35/50ms delay selectable ).
Ciao
Marco
 
marcok

marcok

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#10
To be more precise :
There are 3 versions of PL 4000 1st series
a) 4 channel SQ
b) 4 channel SQ + logic ( my father's units )
c) ambience
C4000T has no peak unlimiter and no rear channel power amps ,
but it has acoustic lens and another type of ambience unit called surround sound.
To be honest , since my preamp is C4000 I don't know the behaviour of the surround sound unit .
Ciao
Marco
 
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Wayne G.

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#11
marcok said:
To be more precise :
There are 3 versions of PL 4000 1st series
a) 4 channel SQ
b) 4 channel SQ + logic ( my father's units )
c) ambience
C4000T has no peak unlimiter and no rear channel power amps ,
but it has acoustic lens and another type of ambience unit called surround sound.
To be honest , since my preamp is C4000 I don't know the behaviour of the surround sound unit .
Ciao
Marco
Click to expand...
Was not aware of a SQ + logic version or one with "ambience". All I have ever seen here is the "SQ" version. Were they European models or put out very late in the series? At the time I purchased my 4000 series 1 (around 1978) new they only had the one version.
 
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