Newly acquired 520 STe questions

[rubber_jonnie]

You can just about fit a Meanwell RD-50A, which matches the STs 12v & 5v requirements, it would however need a little bit of wiring, but nothing complex.

[stween]

I've done this, and ... it's possible, but it's a tight squeeze as you suggest. It's tricky to fit onto the metal frame, and required a little bit of confidence between hacking the PSU frame and watching the couple of youtube videos/reading a couple of forum posts for how others approached it in the past. It was fiddly enough that I wondered at the time if the RD-35A (I think?) would have been a better option.

[olivier.jan]

I recently installed a Meanwell (RD-65A) in a MegaST and this time I used a zip tie to hold it in place.
By using one screw from the original PSU and the zip tie around PSU+Metal plate, it sits firmly in place and no need to modify the original plate.

IMG_0886.jpeg (281.08 KiB) Viewed 3292 times

No metal plate or original Atari part were harmed during this upgrade.

[HigashiJun]

@olivier.jan

Isn't your PSU fan just blowing (uselessly) air on the metal plate of your Meanwell ?

[olivier.jan]

Yes clearly, I need to find a better way, even though I’m not sure the fan is necessary with a Meanwell. Maybe simply reverse it to extract air from inside the Atari case.

[HigashiJun]

I made that on my Mega ST (now sold):

PSU.jpeg (453.98 KiB) Viewed 2556 times

[Jobbo]

My order (minus the power supply, will figure that out later) has arrived.

I've got a 4meg upgrade for this 512k machine.

But before I break anything, what is the trick to getting the old simms out?

Here's a picture of what mine look like.

[Jobbo]

I got impatient and just went for it. Those black simm board slots are not very forgiving after 30 years. But it seems to have gone okay with a lot of wiggling and concerning squeak noises. We'll see if it still boots later!

[Dlfrsilver]

...My board looks likes someone has done something to it, there's some wires going from the sound chip and cpu to a piggy-backed little chip below the ram...

It's factory bodge job. You got an early revision. Later revisions has the chip soldered on the motherboard. I can't remember what it was for though.

Yes, earlier revision, this is a beta motherboard. He will possibly encounter the CPU/DMA bug, this has to be debunked and tested before installing games or preparing an ultrasatan on this STE.

@rubber_jonnie the 2 big capacitors on the motherboard must be replaced, they ensure stability for the 5v, and they are mostly dry now with the years. So he has to make them replaced as well.

[Jobbo]

Welp, it looks like my Atari isn't working now after I took it apart and upgraded the ram.

It turns on but only shows a white screen that cycles through some bars and ends up with just black vertical bars.

The floppy drive light isn't coming on and the drive isn't making sounds.

So, maybe I just didn't put it back together again properly, or the ram isn't working.

Anyone have any suggestions?

Thanks for any help.