I have an older Tivo that I used to watch TV for over a decade with zero issues. Recently had a power outage in my house thta blew the power supply of the Tivo. I repaired it, and now it is causing me eyestrain. I replaced it with a stock power supply, same thing.
Same Tivo, same TV, same HDMI cable, same everything except an internal power supply, and that is now making TV unwatchable.
It's not the same Tivo. It's a Tivo that experienced a power surge. You are assuming that a surge strong enough to blow out a power supply stopped right there and didn't forward any current onward.
I'm no electronics expert, but why would turning off the power kill capacitors?
This is a fascinating observation, wish I had some insight to offer. Perhaps the TV has a fault as well?
Sunspark The purpose of a capacitor is to regulate power. If the power goes out, it's going to dump it's voltage to try and keep the device going. This model of Tivo is notorious for having substandard capacitors, and sudden discharges strain capacitors and that s what blew these two.
This is a fascinating observation, wish I had some insight to offer. Perhaps the TV has a fault as well?
It's not the TV as other devices are fine. I did use a bad choice for a replacement cap (it has a high ripple value) and I thought that could be sending oscillating voltages to the board, but I swapped the power supply with a known good stock power supply and no change. I did swap the coax and HDMI cable and that seems to help, although I have no idea how a power outage would hurt those, unless it was spiking power coming from the battery of the UPS that was runing the Tivo. I opened the devie and checked all the HDMI pins and they were fine, the video controller on these devices is all part of the SoC so I can't isolate that to check it for damage.
It's an odd one, but ne more thing to throw in the pile of possible causes to our issue: Bad power input
Maybe the new power supply has poor quality parts and introduces noise/fluctuations into the components.
Look into https://en.wikipedia.org/wiki/Ground_loop_(electricity)
I think some power boards can filter the line too.
Yes, and things don't always work the same at different voltages. For example, my old processor would work on both 1.2v (rechargeable AA) and 1.5v batteries, I could hear a subtle difference with 1.5v batteries.
I've seen studies showing that battery recharge speeds are affected by old (presumably wearing) USB cables, and also voltage measurements from different units have variability in output which can be seen with a multimeter.