innercityman

Urei LA4 silver face issue
« on: January 14, 2021, 08:50:38 AM »
My original Urei LA4 silver face is not compressing anymore. It passes audio but no compression. I guess the Opto cells need to be replaced but is there any other investigations I Should do before ?

A photo of the cells inside my LA4 attached...


gyraf

Re: Urei LA4 silver face issue
« Reply #1 on: January 14, 2021, 09:30:11 AM »
..neither LED or LDR are known to fail, I'd look for errors beyond the protocells...

/Jakob E.
..note to self: don't let Harman run your company..

Khron

Re: Urei LA4 silver face issue
« Reply #2 on: January 14, 2021, 09:35:54 AM »
Something between the audio input and the detector circuitry perhaps?
Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

JohnRoberts

Re: Urei LA4 silver face issue
« Reply #3 on: January 14, 2021, 10:11:23 AM »
could be side chain related, but I would expect open side chain to command max compression, of course open circuit from side chain to turn on the opto gain reduction could result in no compression.

JR
It's nice to be nice....


 

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