Temperature and video signal dropping out

[DusteDdk]

It's warm these days, and for the first time I had a longer session on my machine (assembled for once), maybe an hour into the session, the TV started dropping the signal, it'd catch the signal for a frame or two, then drop it, it'd repeat like that, like something drifting.. I pulled the case apart and took off the keyboard, and gently pressed on the kawari, it was hot, not VIC2-leaves-permanent-burn-scars hot, but hot, blinking stopped immediately hereafter and didn't return.

What are the acceptable package temperature for the kawari ? I wonder if that's what caused the issue. ? Have you done any thermal testing ?

[randyrossi]

The FPGA is rated up to 85 C but I did not see temperatures go that high in my testing. High temps can definitely cause that kind of issue in FPGAs though. The tools only guarantee timing constraints can be met across the operating temperature range. You can try throwing on a small thermal pad on top of the FPGA to see if it helps.

On Wed, Sep 6, 2023 at 5:10 PM Jimmy @.***> wrote:

It's warm these days, and for the first time I had a longer session on my machine (assembled for once), maybe an hour into the session, the TV started dropping the signal, it'd catch the signal for a frame or two, then drop it, it'd repeat like that, like something drifting.. I pulled the case apart and took off the keyboard, and gently pressed on the kawari, it was hot, not VIC2-leaves-permanent-burn-scars hot, but hot, blinking stopped immediately hereafter and didn't return.

What are the acceptable package temperature for the kawari ? I wonder if that's what caused the issue. ? Have you done any thermal testing ?

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[DusteDdk]

Thank you for your reply, the FPGA was nowhere near that temp. But the 7805 was pretty toasty, maybe it does thermal cutoff, but I'd not think the kawari needs as much juice as the VIC2, maybe more sensitive? Then again I'd not expect the kawari to come online with a usable picture if it lost power during operation (I'd expect some registers to be messed up or something like that).

If you have any additional remarks, I'm very interested. In any case, I believe this can be closed as there's nothing in particular pointing to the kawari being at fault (except that the machine continued operation while only the video signal started dropping out).