Phase Linear Preamplifier 3300 Series II SM

NavLinear said:
Attached is the 3300 II Service Manual.
Click to expand...
Hi
i am from France and i see you forum with PHASE LINEAR 3300SERIE II and i buy one i do an upgrad with a kit LDX TECHNOLOGIES because it was noisy
after the upgrad it is better but i still have a hum can you tell witch capacitor could be the problem
Many thanks if you can answer because i don't know if you are on this forum
Alain
 
I've read about the LDX kit on Ebay - it seems that the upgrade kit includes a regulated power supply, updated IC's and ??? If you could help us in understanding what was replaced that would help. The noise you're hearing may not be caused by a capacitor but we need a baseline of the modifications to help.

A Nav welcome babe:
 

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NavLinear said:
Is the hum heard in both channels?
Click to expand...

Yes the volume does'nt change the hum from 60 to 0db
when i put balance full on left and vol to 0db i have a little hiss who disappear at 6db
I have change the four IC and use a power supply regulator board witch whas in the kit
Thanks for your attenetion
Alain
 
BASSINSTINCT said:
and the tone switch does more hum when it 's on
Click to expand...

The tone switch may be amplifying the hum when the gain is increased.

Have you cleaned the potentiometers and front panel switches? Since the hum is in both channels the source may be coming from your power supply. Did the unit hum before the modification? Is the hum present when you change signal sources?

Do you have an oscilloscope and function generator? Those could help us in pinpointing the problem. If not we'll have to take different steps in identifying the problem.
 
It's late here so off to bed. Good luck and keep us posted with your diagnosis.

Nav
 
Does this kit include new power supply capacitors ? If not, it may be the power supply is dirty. If its typical full wave rectification, the hum should be 100 hz. If its a ground loop problem it would be 50 (in Europe anyway). A scope check on the power supply output to check for ripple would tell it, but maybe try replacing the power supply capacitors if you don't have a scope and have not done it already.
 
gadget73 said:
Does this kit include new power supply capacitors ? If not, it may be the power supply is dirty. If its typical full wave rectification, the hum should be 100 hz. If its a ground loop problem it would be 50 (in Europe anyway). A scope check on the power supply output to check for ripple would tell it, but maybe try replacing the power supply capacitors if you don't have a scope and have not done it already.
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HI
I have pull off the power supply kit and replace with the 2 capacitor and the bridge and it is a little more noisy and when i power off i can ear from 5 secondes the hum decrease slowly
i have record the noise but i dont know how to join on the forum
it is 08.25 on the morning in France what time is it where you live ?
Many thanks for your help
alain
 
BASSINSTINCT said:
HI
I have pull off the power supply kit and replace with the 2 capacitor and the bridge and it is a little more noisy and when i power off i can ear from 5 secondes the hum decrease slowly
i have record the noise but i dont know how to join on the forum
it is 08.25 on the morning in France what time is it where you live ?
Many thanks for your help
alain
Click to expand...

Alain,

I'm 9 hours behind you as I'm on the west coast - California.

Can you post photographs of the modifications - at least some of the power supply? A schematic of this modification could help.

When you went back to the original power supply did you re-use the capacitors you pulled from the power section? It may be easier to troubleshoot this issue if we start with the original configuration. Once the problem is found and repaired the upgrade you purchased should drop in place.
 
Is the hum present regardless of which input is selected? Do the phono inputs have shorting plugs in them?
 
Let's start over... what amp is this hooked to when you hear the hum?
 
laatsch55 said:
Let's start over... what amp is this hooked to when you hear the hum?
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Now i have complety remove all components added with the kits and clean all switch and potenetiometres as fine as possible without desoldering all pots
The hum when it start is very diminush and after 10 second it is silence and when i turn off i ear for few second hum and scatch like a capacitor whose leak
i join schema off the kit i buy
 

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The on-off muting in the 3300 is a pair of transistors, Q103, Q203...from your description if these transistors are getting noisy they can cause this.


WHAT AMP is this hooked to when you hear the hum??
 
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