Onkyo NR656 No HDMI Out On Main

Check L8001-L8004, D8401 if is mounted.

Measure voltages and resistance on ech pins p8001, compare with working hdmi out P8021. Probably damage is q8401.

Sorry, but you don't have skills and knowledge to make a good diagnosis, with no skills you can easy damage board.

Q8401 is do-able but it is a royal pain. There is a small pad on the bottom that acts as a ground point and also as a heatsink. You have to get the chip pretty hot to get this thing off and installing a new one is not trivial.  Essentially, you have to mask off the area around the chip with kapton tape and then heat the chip up with a heat wand until the solder on that ground lug goes molten. It takes a couple of minutes at 380 degrees Celsius but it will eventually go soft and by that time, the pins have been getting hot for a while and will also be molten so you can use a suction device to lift the chip off.  Once off, you have to clean the pads (leave the solder on the ground lug), put some "no clean" flux on the ground lug and place the new chip carefully aligning it.  Note: the solder you left on the ground lug will lift one side of the chip a little but this is ok because you will start by only soldering down one of the 4 sides.  I usually "tack" one of the corner pins and recheck that all the pins are still aligned.  I don't really aim for 1 pin, I put a blob of solder that covers 3-4 pins.  This helps keep the chip aligned because 1 pin will bend but 3 won't.   If the chip shifted, I simply have to heat up that corner again to "massage" the chip into the correct position so that all of the pins are aligned.  Next, I will tack the other corner on that side and check again with a blob that covers 3-4 pins.  After making sure that everything is still aligned, I will drag solder with my concave tip to mount the rest of the pins on that side.  At this point I have 1/4 of the chip soldered down and the remaining pins are hovering over their respective pads.  I now hit the chip with the heat wand on my soldering station set to 380 degrees.  I watch closely while I heat up the middle of the top of the chip.  After a couple of minutes, the solder on that ground lug will go molten and  the chip will settle down onto the pins nicely.  I now let everything cool for a bit after which I lay down some flux and drag solder all 4 sides.  If I see bridges, I will lay down some more flux, clean my solder tip and drag solder across the area multiple times until the bridges are removed.

From looking at the schematics, the NR555 seems to have the same HDMI board so it should be able to be made to work. To move the "Personality" of the NR656 onto the NR555 board you will need to remove Q7001 and move it to the new board. Q7001 is a small 8 pin eeprom that holds the program for the system and while the device is the same, the software installed on it is different for each system. If you are uncomfortable with removing a chip like this, you can use a programmer with a clip and copy the program from the NR656 board and then flash it onto the other board (all done without removing the chip). I would STRONGLY recommend that you grab a copy of the NR555 code first and keep it as a back up just in case.

Once you have reprogrammed the main CPU eeprom you will need to force a firmware update for the whole system so that the VMPU, HDMI, DSP etc. subsystems are updated to the correct levels for an NR656.

I have done this many times and it is relatively simple. The hard part is the time it takes to go over the schematics to ensure that all the other circuitry is correct. For example, on one board I worked on, both models had the same PCB (printed circuit board) but had different PCA's (Printed Circuit Assembly). What this means is that the lower end board had some things missing for things like Zone2/Zone3 and also had a different DAC solution. Fortunately, Onkyo marks the Schematics with "*" to show what parts are different between PCA's so I was able to figure out the delta and move the appropriate parts over.

A quick review of the Service manual shows that the NR555 is a "T5" while the NR656 is a "T6". At a minimum it looks like you will either have to move the front HDMI interface or do without it and you may lose one HDMI port. Removing/adding and HDMI port is a major PITA! Frankly, if it were me, I would replace Q8401 before I tried to move/add an HDMI port. Since their is a lot of plastic in them, you have to be very careful and can't use too much heat. The best way I have found is to use try to pull off as much solder from the case as I can and then try to work it free. Next, I use chipquick on the pins and try to keep the hot enough to remove while I work the case free of the board. Again, not a fun job.  The last time I did this I removed 7 HDMI ports from a dead board and only 4 were good enough to reuse.  I trashed the other 3 in my efforts to get them off.


HTH

Todd

Thanks again for the replies.
I think all the solutions at the moment are beyond my skills.
I may get there one day, but right now I don't have the skills or equipment to do it.
I thought it would be a straight board swap or some big component.

I will try to find a local repairer or buy a 656 board.

Thanks