Hello, excuse my english cause I am french
I have bought one k4010 in a store with no problem since the first connecting-up on April 2005 (very happy).
Then I have bought another k4010 by internet on july 2007 and I had several problems :
-
I had invert D9 and RY1 did not commute. After a good position of D9 it was ok.
-
one of the electrolytic capacitor 470µF 25V was squash up during the travel and I replace it by a equivalent in position C34. Maybe I’d better put it in C33 cause it’s bigger size than the original and I had difficulty to insert the holder F1 in depth. So absolute value of -V3 is a little higher than +V3.
3)JR (connector audio in cinch female) was in short-circuit due to the manufacturing of the pcb (short-circuit between tracks audio in/gnd near JR). I resolved that by parting with a cutter, then I could listen the music.
The voltage across R78 to R81 is about 35mV.
But the last problem I have today is that the second amplifier k4010 I have bought has more background noise than the first.
in normal use (preamp connected and mute) the noise is about 3 times more audible than the right channel with sizzling.
When I make a short-circuit to the amplifier input using a short circuited cinch plug, the noise persist, but a little lower.
When I unplug the amplifier input, the noise becomes outsize.
(Note : on the both amplifiers, I add C41 and C42 10000µF 63V for a better bass sound. I put them together in a metal box with ventilation - speakers are bose 901 VI)
I hope you can help me to get the same low-noise on the both amplifiers and I thank you in advance (in french that would be easyer for me)