Chosen Solution
I have an Onyx 550 showing no signs of life (light ring on power plug doesn’t even light). Swapping in a known-good logic board confirms that something on the board is the problem. The C1 capacitor rattles when I shake the board, so I’m thinking it has dried out and simply replacing that might fix the problem. Do you know the full specs of the C1 capacitor? Some specs I can read/see on the cap: surface mount designRubycon (manufacturer)220 uF35 V105 degrees C (apparently the top end of the rated operating temperature range)NO144 (not sure if that’s exactly what it says or what it means)10 mm diameter and 10 mm highpresumably this is an aluminum electrolytic type If I have all that right, then it narrows down the selection of caps at Mouser pretty well. But there is at the least a question of the low-end temperature rating, and beyond that I would be happy to have someone confirm my overall assessment above.
Hi to try if the cap is the problem you can replace the cap with a “normal” electrolytic cap with 220µF and 35V and solder it to the SMD solder pads. If the board works again you can go for a SMD cap and replace the test cap. For the test cap you dont have to go for a 105°C model, as it is only for short term testing.
