Printer freezes at random points/prints

Hello,

I've been having this strange issue lately. I've had a prusa i3 type printer for over three years now and it's been running Marlin (don't remember version but whatever was current at the time, mid 2015 ish). I had never had a problem. I have octopi on it, no problem with that either.

The last month or so, I started having the following problem:
1) First appeared, I was using octopi and the print (prints that have printed successfully before, same gcode) would stop in this manner: a) octopi would say that the serial connection was lost b) the printer would freeze and all temperature controls would stay put (yikes!).
2) After resetting octopi (which would reset marlin as well) everything would work and then after a random amount of time it would happen again (large or small print didn't seem to matter either)
3) I did all sorts of troubleshooting with octopi (reformat card, reinstall, update, buy new card and reinstall etc) to no avail
4) I removed octopi completely and started printing from SD.
5) Everything seemed to work for 2-3 days again no problems to which I started thinking that my raspberry pi was faulty. And then boom! Half way mid print again, the print froze (from SD, no octopi connected) and it was completely unresponsive other than holding again the temperatures (yiiiikes!). What I noticed is that the status string on the bottom of the screen instead of saying "Printing..." it had "/ " which really looks like a buffer overflow of some sort....

Reason for posting is that I wanted to check with the community and see if anyone else has bumped into this before. At this point I am fairly certain the arduino mega board might have acquired some sort of hardware problem after all these years or maybe the flash chip has been corrupted or something. It really seems that there's a hardware problem though (since I have been printing for years no problem).

So, has anyone seen this before? Any input would be appreciated. At this stage I am planning to grab another mega and install latest marlin (good chance to update) and start printing and see what happens...

Thanks again,
Stratos

Have you made recently any kind of changes in your house regarding the electrical installations? Such as changing lights or appliances?

I ask this because I remember having had this kind of problems with my first printer. It turned out that the problem occurred
every time someone switched of a fluorescent lamp in a room that was attached to the same fuse. I changed the lamps to LED
lamps and the problem never happened again.

Thanks for your response!

To my knowledge I didn't do anything but the problem is so peculiar I wouldn't be surprised by a weird thing like that. On the other hand, what I did is grab a fresh copy of marlin and install it on another mega. Everything went well but it appears that now I have another (maybe not unrelated) problem. The heater is not up to par (getting thermal runaways). I now suspect that there might be something wrong with the heating element/thermistor or the ramps board (the only things I have not changed). I might just go ahead and replace those as well and see if that solves all my problems once and for all. Honestly, that rig has printed thousands of hours at it's current configuration so I wouldn't be surprised if one (or more) of the components is showing fatigue.

I'll try to keep this thread updated for posterity.
Stratos

Just an update. I ended up replacing the whole heater block assembly and currently the printer seems to be operating smoothly. It might have been that but I am keeping it under probation