Phase linear 4000

V

v65magna

Journeyman
Joined
May 6, 2019
Messages
69
Hi everyone hope everyone is well , my question is when hooking up the 4000 pre amp to my 700b I get really low volume on both channels I say a 1/4 of the 700b output , would this be the power supply , I have the second version of the 4000 where the transformer is in the rear, I checked the solder joints over a thousand times with a magnifying glasse I don’t see any cracks no where any suggestions would be much appreciated ps my 700b is 100% functional when I hook it up to my other pre amp ,
 
Could be a million things. The only way you will find out is to pull a service manual/schematic and trace where you are losing gain in the signal path.
 
v65magna said:
Thanks
Click to expand...
Wish there was a magic bullet we could tell you about, this is one of those you will just have to investigate and find. Start with the power supply section and make sure you are getting the ~30V that powers these beasts.
 
What comes to my mind first is that the -20dB button may be depressed...
I’ve done that a few times...
 
If both channels are equally reduced, I would look at things common to both channels. The power supply in the 4000 is a good start. The electrolytic capacitors in that power supply are likely 40-50 years old. The common life expectancy for electrolytic capacitors is 15-20 years.
 
mlucitt said:
If both channels are equally reduced, I would look at things common to both channels. The power supply in the 4000 is a good start. The electrolytic capacitors in that power supply are likely 40-50 years old. The common life expectancy for electrolytic capacitors is 15-20 years.
Click to expand...
Thanks for the help I appreciate it a lot, would U know which capacitors are for the power supply , and again thanks for helping me
 
PL4000 electrolytic capacitors in the power supply are:
C2 200uF 100V
C3 470uF 50V
C4 100uF 35V
C6 100uF 35V
C7 470uF 50V

Do you have a copy of the PL4000 Service Manual?
 
mlucitt said:
PL4000 electrolytic capacitors in the power supply are:
C2 200uF 100V
C3 470uF 50V
C4 100uF 35V
C6 100uF 35V
C7 470uF 50V

Do you have a copy of the PL4000 Service Manual?
Click to expand...
Thank u for that information on the capacitors for the power supply ,, I will download the service manual , does what’s happening when I hook up the 4000 to my 700b with the low volume on both channels maybe the capacitors for the power supply does kinda make sense because of the low volume ,,
 
After checking PSU , in case the fault persists ,
remove all the boards except tone amp and logic boards .
This is the minimum config .
Use ,if you have ,a cassette deck as AC voltmeter connected to main output .
Don't use a power amp when you move and remove boards .

Ciao
Marco
 
marcok said:
After checking PSU , in case the fault persists ,
remove all the boards except tone amp and logic boards .
This is the minimum config .
Use ,if you have ,a cassette deck as AC voltmeter connected to main output .
Don't use a power amp when you move and remove boards .

Ciao
Marco
Click to expand...

Correct Marco, there are very few boards that actually do anything worthwhile in a PL4000
 
Gepetto said:
Correct Marco, there are very few boards that actually do anything worthwhile in a PL4000
Click to expand...
I partially agree with you , Joe .
For me Autocorrelator and Peak Unlimiter functions are a good " Dynamic range ricovery system "
Good for vinyl records and to compress the dynamic for modern soundtracks in case
you connect the TV to your hifi system . For CDs are moreless useless .
Without special functions is a normal preamp based on general purpose transistors .
( What they had at that time )
IMHO .

Ciao
Marco
 
You must log in or register to reply here.
Back
Top