How long can I keep my MSX Sanyo Wavy 2 on?
I always look at it like this: If you can play games for like 15 minutes-30 minutes without problems, leaving it on for hours/days wouldn't be any different.
All electronics will fail at some point but most can last decades if treated well (source: the fact that many msx computers and other computers from that era are still functional!). Imho the weakest link is the power supply, but like thespecialist said, if your PSU was already in trouble, you would have had other problems as well.
So don't worry about it too much, like someone said sarcastically to me when I asked him how to keep my computer in mint condition: "The best way to preserve your msx is to never turn it on".
In other words, just enjoy your msx 
Out of curiosity: Is there any reason you wanna keep your MSX on for days? because of lack of save-feature in games?
The longest MSX experience I have actual record of is 7 days of non stop power on. The person couldn't save the game and wanted the all time high score for Kings valley. He succeeded 
and the MSX is still working.
I think that every machine that still works today has passed the test allready. All other machines that had problems have either been repaired or allready died. So via natural selection only the best made it up until today.
I was mostly saying that the components are 30 years old, so I would not make a habit out of keeping it on all the time. But I agree with the others that it’s not a great risk. It’s not like, if you keep it on for X hours there is an Y% chance of failure. Most likely there will not be any issues with keeping your MSX on for a couple of days, at least until your MegaFlashROM arrives. In the end, with my CX5MII I was just unlucky (and I’m in the process of repairing it ).
I would definitely not stop yourself from enjoying your MSX for this small concern. Enjoying the machine is the no. 1 priority! So please don’t hesitate to do as you were thinking.
p.s. If you are entering Basic listings, you could consider connecting your MSX to your PC via the cassette input/output, and use your PC as a tape recorder to preserve the games you painstakingly entered!
OK....I like what I am hearing Grauw . How do I go about doing that? Is there hardware and software tutorial that allows me to save from MSX to PC? Take in my mind...my MSX 1 have only BASC 1...the oldest version of BASIC possible and there is no terminal software. So I may need to enter code to communicate between PC and MSX.
So let us get the cable or hardware part first out of the way. What is it called? Can you show me an eBay link for it? I may order that right away and use it until MegaFlash ROM is out...
and how do I transfer code from MSX to PC and back from PC to MSX to continue the codes I entered and not start from scratch all the time!?
Honestly, I want to use my MSX and abuse (productively) without feeling an ounce of guilt....it is a toy that I want to enjoy!
For example, my NES I am actually enjoying it FIFITY BILLION times more than any emulator and yesterday when I turned it on and the game showed gibberish and crashy screen I was actually jumping up and doing smiling...going hehehehehhe
this experience I can never get in an emulator...the emulator can never die, can never crash and the rom in the emulator can never break...ZzzzzzzzzzzzzzzzzzZzzzzzzZZZZZZZZZZZZZZZzzzzzzzzzzzzzzzzzzzz.....
