TV repair - episode 2

[TheMG]

Panasonic TC-P65S1. Previous repair was to replace film caps on one of the sustain boards which were failed and shorting out, causing the TV to essentially not come on (trip instantly on power-up).

While I was at it, I also checked all electrolytic caps and replaced anything that was out of tolerance or close to being out of tolerance, so I'm pretty confident capacitors are not causing this different problem.

The TV works absolutely great except for one issue - random glitches and signal loss on the HDMI ports. This only happens when the input signal is 1080p at a refresh rate greater than 24Hz, and the higher the refresh rate the more glitches. All 3 HDMI ports behave exactly the same way. This TV officially supports up to 1080p60 display mode, so that's not the issue.

Weird thing is the amount of glitches seems to vary based on the length of the HDMI cable used. Counter-intuitively: longer cables work better than shorter ones!!! I've tested this extensively with a multitude of different cables and source devices.

Would it be correct to suspect an issue with the HDMI 3-way switch IC, since it's the first thing the signal passes through and cable length affects the behavior? The IC is a Sony CXB1444R, for which I can not find a datasheet.

Anyone seen anything like this before?

[fzabkar]

Do you have a circuit diagram?

Is there an array of low capacitance ESD protection diodes on the HDMI port?


Edit:

If the problem occurs on all HDMI ports, then I suppose that rules out the ESD arrays.