Onkyo TX-NR509 No Sound issue

I'm no expert on Onkyo and haven't worked on a TX-NR509 but they do seem to run hot and more so than their Pioneer counterparts. I would check the ripple on the supplies to the HDMI chip and check/replace any electrolytic capacitors around it, which may help with this. A small heat sink bonded on won't do any harm if you think its still too hot.

The loss of network/usb/audio will most likely be the DSP chip and/or the NAND flash connected to it. I'm currently trying to fix a TX-NR808 with the same issue. I would replace the NAND for one that doesn't have any bad blocks and load it with a firmware dump from a working unit. Try reflowing the DSP before condemning it as it may just be a failed solder joint. Replacing or reballing it is the only other option.

There is a NAND firmware dump for the TX-NR509 here, (4th post from the bottom):

www.elektroda.pl/rtvforum/topic2825727-180.html

I got lucky with a TX-NR807 recently and just reflowed the DSP, which got it going. I pre-heated the board using a mobile phone hot plate, then put plenty of liquid flux under the DSP and heated it for a 60 to 90 seconds to reflow the joints underneath. How long it lasts though, remains to be seen!

I'm wary of any replacement DSP chips from China. A lot are fakes or salvaged parts and anything that is claimed to be brand new is likely to be anything but.

I do have a reliable source in China for semiconductors but these particular parts are becoming scarce and I think the ones I've bought are all used reballed ones.

I would try reflowing your original one first and if that doesn't work look at the NAND flash before embarking on any BGA rework as it may not be the problem.

Onkyo AVRs from 2009 to 2013 seem to be the worst affected by the faulty TI DSP chips but Pioneer have their share of dodgy models too, so be careful what you buy on eBay.

I download the service manual and look at the hardware it uses before bidding. Most of the older models don't usually go for much money now because of the well known faults, even if they were £1000 new.

Thanks both. In hindsight I perhaps should have walked away from messing with it (could say the same for many things I tinker with) especially if most of the 'new' ic's are reballed old ones which I wasn't aware of when I started!
In this instance the DSP has been reflowed quite a bit so suspect it will be the main culprit. Unfortunately I dont have access to reballing equipment so are asking my friend for help with this who has.
I take it (other than ic's which just die due to faults) that 90% of these are dry joints natuarally which can then become shorts or other faiulure depending on how well / badly thay have been reheated. If so then reballing with leaded solder would help no end ?