Pioneer VSX-LX51

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R

RS232

Member
Joined 2006
Hi everybody
Here to ask for a bit of help and advice regarding this 7.1 home cinema...
Problem:
Completely dead apart from blinking blue LED at the centre of the amp (HDMI 1/HGMI 2) and doesn't wake up after reset procedure.
Traced aux (stand by) voltage all the way to the main controller on the front panel and found to be correct including the signal from the "on" button.
After much head scratching and looking at the service manual I found that the "Wake Up" voltage from the aux power supply is low but not sure if it is (are) my voltmeters at fault.
Can someone help a depressed member before I scrap the thing....
Regards

PS: Yes I disconnected the flat cable and the voltage didn't change
 

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rayma

rayma

Moderator
Joined 2011
If the two series parts are good, then it must be be of the three shunt parts instead,
or a fault on the pcb. First look at the pcb carefully. If that is ok, the capacitor would be the least likely.
So just measure the resistor. If that seems ok, then replace the Zener.
 
R

RS232

Member
Joined 2006
I disconnected this board from the rest of the amp (flat cable) and nothing changed.
I problem is that all the components on this board are very small SMDs and not easy to work on/with but will have a go at it (noting to lose is a free amp)
Many thanks
 
rayma

rayma

Moderator
Joined 2011
It appears that the rectifier does not make DC, but a pulsating positive AC half sine
that is clamped by the Zener diode. If possible use a scope to check this after the 3.3k resistor.
There should be 8mS wide positive pulses, with 8mS of 0V in between them.

The amplitude of the pulses is the Zener voltage. 5.1 volts. The meter will read an average of this,
which is around 2.5V. Maybe there is no fault there after all.
 
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