Uploaded May 2022 | Updated September 2026, 3 weeks ago
Part one left the miniframe in dire shape, unable to boot or do anything more that blink some diagnostic LEDs. In this video, I use a diagnostic ROM to examine memory and set breakpoints in the boot loaded. I replace a whole bunch of 74XX logic, then I get out my logic analyzer and troubleshoot the problem. By replacing some 74LS461 ICs and replacing a PAL, I get it to the point where it boots, but still experiences occasional memory errors and core dumps. I then transition to playing with a second miniframe, one that works quite a bit, as well as a Convergent terminal that connects to the miniframe. I succeed at hangman, but fall into a pit while hunting the wumpus. For more electronics videos, see smbaker.com
Part one left the miniframe in dire shape, unable to boot or do anything more that blink some diagnostic LEDs. In this video, I use a diagnostic ROM to examine memory and set breakpoints in the boot loaded. I replace a whole bunch of 74XX logic, then I get out my logic analyzer and troubleshoot the problem. By replacing some 74LS461 ICs and replacing a PAL, I get it to the point where it boots, but still experiences occasional memory errors and core dumps. I then transition to playing with a second miniframe, one that works quite a bit, as well as a Convergent terminal that connects to the miniframe. I succeed at hangman, but fall into a pit while hunting the wumpus. For more electronics videos, see smbaker.com
![Raspberry Pi 4 Thermal Investigation [Part 2] Frequency cap, Throttling, & Real-world test](https://i.ytimg.com/vi/D5YuP0IDFKU/mqdefault.jpg "Raspberry Pi 4 Thermal Investigation [Part 2] Frequency cap, Throttling, & Real-world test
In this video I continue taking a look at the thermal properties of the raspberry pi 4. I spend some time looking into frequency capping in detail. I even take a heat gun to the pi to make it cap and throttle all the way down to 300 Mhz. Then I do some real world tests to see how much heat comes from youtube streaming to an HDMI monitor, copying data to/from the USB3 port, and compiling software in the background. Then I throw the same delta fan on it that I showed in the previous video and demonstrate that performance returns back to normal.")
