NS-R5101HD same as Pioneer VSX-819H-K Receiver

Was working perfectly fine for many years. 5.1 setup with Paradigm Atom speakers and Sony sub.
Connected to TV via SPDIF cable.
One day sound "popped" and now LED shows volume numbers go UP and DOWN(knob or remote), but sound level stays the same.
Sound is distorted and when plugged in headphones, one channel only.
Tested all transistors on the AMP board, - nothing shorted or open. Tested all diodes. Caps seem fine.
Same tests with main board.
All voltages are seems there.
The rest of the boards tested the same also...


Any help is highly appreciated.

 

[Dave Platt]

In article <8e63af3e-dc4d-4611-b9eb-003c89faabf5@googlegroups.com>,
<999bga@gmail.com> wrote:

Was working perfectly fine for many years. 5.1 setup with Paradigm Atom speakers and Sony sub.
Connected to TV via SPDIF cable.
One day sound "popped" and now LED shows volume numbers go UP and DOWN(knob or remote), but sound level stays the same.
Sound is distorted and when plugged in headphones, one channel only.
Tested all transistors on the AMP board, - nothing shorted or open. Tested all diodes. Caps seem fine.
Same tests with main board.
All voltages are seems there.
The rest of the boards tested the same also...


Any help is highly appreciated.

Looking at the block diagram in the Pioneer VSX-819-HK service manual,
my suspicion would be that something may have gone bad on sub-assembly
K (the INPUT-819 board). In particular, IC801 (R2A15218FP) is a big
monster which performs the analog input selection, analog/digital
switching, and volume adjustment functions. It has a simple control
input (DATA and CLOCK inputs from the central micro-controller)...
could be something like an I2C or SPI interface I suppose. If this IC
has developed an internal fault, then the analog signal paths would go
wonky, and the microcontroller which runs everything would probably
not know about it.

If you have an o'scope, you could feed a test signal to the receiver's
AUX inputs, select AUX, and then look at the signals going ito pins 75
and 76 of IC801 (AUX-In to the selector) and at the various outputs to
this IC. If I'm reading the block diagram correctly, pins 54 and 55
should feed the selected input signal out to the A-to-D converter
(there are on-chip level controls), while 21 and 22 drive the signal
out to the "front right" and "front left" amplifier channels (there's
a whole bunch of switching, volume control, and other stuff going on
inside the chip in this path).

If the signal isn't getting through IC801 properly, you'd either need
to replace this big IC (if it's even available separately) or replace
the whole K sub-assembly board.