... and so it begins (520stfm upgrade).

[retrotronic]

Is it through hole RAM or smt?

SMT

I would suggest caution with a heat gun. I did some tests with a dead ST board and they popcorn very easily.

What temp did you have the heat gun set to? Did you use a nozzle to direct the heat ? I'm guessing around 350 degrees is adequate for the job, with plenty of solder flux on the ic legs.

I certainly wouldn't use a heat gun on its own to remove through hole RAM.

For through hole I have a Duratool desoldering station.

Another option is to just cut the legs on the RAM then you can use a standard soldering iron to remove them one at a time.

Thanks for the tip. Seen this done on a ZX Spectrum repair video.

If you're going to start using heat guns I'd suggest you watch a lot more videos on YouTube first and practice on something you don't care about before you start work on your ST.

I got some stuff I can practice on

[rubber_jonnie]

I can't recall the temp I used, but 350C sounds about what I tested with. I used a largish nozzle, but you need to be super careful and not spot heat.

It's very easy to get focused on what you're doing and forget to make sure the board is warmed up across the area your working. Keep the wand moving and don't just go for one IC at a time.

As well as lots of flux you might want to add some leaded solder to the legs with a soldering iron as this will drop the melting temp a bit.

I also used hot air on a Spectrum RAM repair, but not until after I'd used my desolder gun to remove nearly all the solder first. The heat gun was just to melt the more difficult pins that had traces left, and the same advice goes here too as the Speccy PCB is also very easy to popcorn.