My Radiomaster R81 V2 receiver have overheat problem now. I tested two receiver and have same problem.
input voltage is exactly 5.00 volts(I checked it with voltmeter)
It have no shorted part. It operates well and RSSI is very good. signal is strong. but its temperature is very high and I almost got burn, glue attached to it was melt.
Did you replace/resolder the cables to the receiver as well when you tested another one? Can’t really think of another source for the problem other than that, or an inherent design flaw.
Do you have an IR thermometer to get some actual numbers? Some chips just run very hot. What kind of glue is it that melted? Hot glue?
High resistance at a bad solder joint can heat it up. Would be helpful if you could determine how hot it actually gets, and what component causes it. The STM32 has an allowed range of up to 105C for example.
Was the insulation tube originally attached to the receiver or did you attached it.
On pictures of shops I see the receiver without any covering so it might be necessary for some components on it to have some airflow for cooling. If you dismantel the cover can you identify which component getting hot?
Show pictures
What component on the receiver is heating up exactly? As I wrote, the allowed max temperature for the ESP32 is 105C, that’s very hot. Anything above 50C feels “hot” to the touch. So maybe it’s running completely within spec now, but heated up a bit too much when it was insulated, which wouldn’t surprise me too much. Did you wrap it yourself?
Not saying something definitely isn’t wrong, but you’ve checked two different units and they both are running hot, maybe that’s just the way they work. In that case you could always put a heatsink on the hot component.