RJs Adventures in Mega land III

[atari030]

That's a bloody good result. Well done.

[rubber_jonnie]

That's a bloody good result. Well done.

Cheers

I had to chuck the whole lot at it, schematic tracing, logic probes, multimeters, scopes.

I was about to chuck the logic analyser at it too when I did one last run of the scope over the data lines and they just didn't match the good machine I had.

Just realised I need to sort out a PSU mount too, annoying as I have several spare ST PSUs, and I even have a working Mega PSU board, just not the metal tray.

[atari030]

I'm going to have to do that with my spare MegaST and MegaSTE. I've been sidetracked recapping PSU's and repairing STE boards for the last few weeks. What I did find was that MegaST PSU's seem to be the same PSU as ST's. Both mine had dodgy ASP's supplies and the one other ST I had with an ASP crapped itself too. Not really impressed. I think I have one of every ST PSU in the stable now.

This looks like a good frame solution;

https://centuriontech.eu/product/megast-psu-bracket/

[rubber_jonnie]

I'm going to have to do that with my spare MegaST and MegaSTE. I've been sidetracked recapping PSU's and repairing STE boards for the last few weeks. What I did find was that MegaST PSU's seem to be the same PSU as ST's. Both mine had dodgy ASP's supplies and the one other ST I had with an ASP crapped itself too. Not really impressed. I think I have one of every ST PSU in the stable now.

This looks like a good frame solution;

https://centuriontech.eu/product/megast-psu-bracket/

Yep, in terms of output, there really isn't much difference, and aside from the physical connector, which could be changed easily, the only major difference seems to be the fan bracket, which if you have a Meanwell RD-50A like I have in my Mega 4, is irrelevant as the RD-50A runs really cool.

I did find the Centuriontech bracket, however they are out of stock, and on contacting them, I've been told they won't be making any more

So I can either find a dead one and fit my spare PSU to it, or hope I can find just the frame somewhere. Annoyingly the ST frame has some slight differences that mean it doesn't quite fit.

[atari030]

Bugger. I've got a meanwell rd-65 I picked up while I was working at Jaycar last year. Its great but too big to fit in the Mega. The power connectors are the same between the ST and Mega. I just desoldered the AC side and badda bing. The Megafile frame is different again......

I guess I got lucky getting a PSU frame last year by the look of it.

[rubber_jonnie]

Bugger. I've got a meanwell rd-65 I picked up while I was working at Jaycar last year. Its great but too big to fit in the Mega. The power connectors are the same between the ST and Mega. I just desoldered the AC side and badda bing. The Megafile frame is different again......

I guess I got lucky getting a PSU frame last year by the look of it.

Yeah, if you got a frame from Centurion, you did get lucky. Might have a go at making a 3d printed one. Shame I don't have access to the metalwork shop from when I was in the RAF, as we made exactly that sort of thing. Asking around now to see if anybody has a spare, even dead, that they'd be willing to part with.

The RD-50A fits perfectly in the Mega BTW, which is how come I have a spare PCB, I just had the RD to hand and decided to swap it out. The RD65 is a LOT bigger, so definitely won't fit the standard Mega mounting plate like the RD50-A.

Meanwell_Mega4.jpg (105.2 KiB) Viewed 449 times

This is in my Mega 4, and what I'm using to test this Mega with.

[DoG]

I use RT-65B in two of my Megas. It's a tight fit though. It's the same size as RD-65.

[atari030]

Wow, that is tight. I'll look into that again, I think. Cheers DoG.

The frame I picked up was original Atari. Sold as working, clearly not but I got it cheap so oh well. Same type of failure as my other MegaST and an older FM. Of the three I have, all stuffed. Low voltage under load.

[rubber_jonnie]

I use RT-65B in two of my Megas. It's a tight fit though. It's the same size as RD-65.

That PSU is quite a snug fit!

[rubber_jonnie]

Well, happily I've managed to secure the metal frame for a Mega ST PSU, so hopefully by the time I've finished sorting the RAM upgrade, cleaned and prepped the case and got everything else together such as screws etc, it'll hopefully be here and I can close everything up

So this one is definitely getting there.