A friend of mine has an Onkyo TX-SR706 receiver that had issues where the HDMI ports didn’t work. All he gets through them is green artifacts.
After checking the interwebs, I see that there is a pretty common failure mode in these where the caps on the voltage regulators for the DAC board go bad, and lead to issues. After probing the regulators with my Rigol DS2072A oscilloscope, I found a regulator with a lot of noise on the output indicating a bad decoupling cap.
Put a good cap across it, and viola, all good. Decided to just go through and replace all the voltage regulator decoupling caps since I was in the equipment.
Here is a video.
Per many recommendations by the forums users over at eevblog.com, I made a few modifications to the boost converter circuit. I increased the size of the output filter cap, and reduced the length of the conductors. I picked up 5% additional efficiency but still fall short of the 80+ percent in the data sheet.
LT1303 Efficiency dataRevised for 17mA out.
In this video I put together a small circuit to test out the LT1303-5. I am not getting the efficiency numbers in the data sheet. See the attachment below for the figures I recorded. Granted I don’t know what Im doing, so if you spot the issue, please let me know… and be gentle. Thx, JZJ
LT1303 Efficiency data
LT1303-5 boost regulator datasheet