Unidentified mod and weird RAM sockets in a 520STE

[Cwiiis]

I just got a good deal on a 520STE, I could use a spare and couldn't resist... I've just switched out the ROMs (though looks like I need to put in some headers on the ROM jumpers, they've been changed...) and was going to stick in some more RAM, but I've come across these weird RAM sockets that I can't seem to release. I don't want to put too much force on anything, can anyone describe how these sockets should be released?

I also spied some kind of mod that I've no idea about... The machine seems to run fine, so I guess it's benign, but there's nothing like it on my other STE - my other STE is a 1040STE though and I notice at the same point on the board there are 3 ICs instead of two, so I guess maybe it's related to address decoding and it's to allow for more RAM? The machine has apparently been upgraded to 2MB but I'd like that to be 4. A sticker inside says it had a PC At Once board installed and removed in '91, could also be related to that?

Pictures attached.

IMG_20231005_155843.jpg (378.72 KiB) Viewed 1391 times

IMG_20231005_155436.jpg (286.6 KiB) Viewed 1391 times

[Steve]

It's funny how every now and then this exact same question gets asked even I asked a while back. It's not a mod, it's an early STe and they all had that bodge on that revision.

I also have the same ram slots in my STe. They just pull out straight and push straight back in. No clips.

[Cwiiis]

Ok, just seen viewtopic.php?f=29&t=5603 , sorry for the noise about the bodge - still want to know about those RAM sockets though!

[Cwiiis]

It's funny how every now and then this exact same question gets asked even I asked a while back. It's not a mod, it's an early STe and they all had that bodge on that revision.

I also have the same ram slots in my STe. They just pull out straight and push straight back in. No clips.

I must have to at least push those tabs back as they've clipped onto the holes in the SIMMs - but it's really just force that's required?

Edit: Ok, just got one out, it's just really, really wedged in there... I guess sometimes you have to ask the questions out loud to realise they're redundant

[stephen_usher]

Ok, just seen viewtopic.php?f=29&t=5603 , sorry for the noise about the bodge - still want to know about those RAM sockets though!

They're the same as used in Sun SPARCstation 1s and 2s. Nothing special, you just need a wire tool to hoik them out.

[Cwiiis]

Managed to get the RAM out and fill it with 4MB, but it appears to only be seeing 2... Maybe I didn't seat it well enough.

[Cwiiis]

Seems these sockets don't like exxos ram, the old cards slot in a lot more affirmatively and work fine - if I mix the old and two new exxos in the previously unused slots, it boots and works but is unstable.

[exxos]

The problem is, most simms are out of spec for the sockets. A lot of them are thicker than 1.6mm PCB (can be 1.8mm) PLUS the solder coating which can make them more like 2mm. Its out of spec for the sockets and it damages them. New sockets can take PCB thickness down to 0.8mm. Mine are 1.2mm plus a thin layer of solder which makes them about 1.4mm. Its well within spec for sockets, but if the sockets are damaged, they don't make good contact. I've seen it a lot on STE where the 2 unused sockets fit my simms fine, but the 2 used sockets sometimes don't make good contact. Originally I used the normal 1.6MM thick PCBs and I couldn't even get them in the old sockets at all. So the only option becomes to replace the sockets

[Steve]

Seems these sockets don't like exxos ram, the old cards slot in a lot more affirmatively and work fine - if I mix the old and two new exxos in the previously unused slots, it boots and works but is unstable.

I think I had to de-solder the layer of solder Exxos puts on his ram for it to work in my black socket STe. Just part of the joys of old retro machines

[Cwiiis]

Seems these sockets don't like exxos ram, the old cards slot in a lot more affirmatively and work fine - if I mix the old and two new exxos in the previously unused slots, it boots and works but is unstable.

I think I had to de-solder the layer of solder Exxos puts on his ram for it to work in my black socket STe. Just part of the joys of old retro machines

Thanks for this, seems this was the trick - I've only done one, but it now inserts with a clear and obvious activation and previously, I don't think it was actually fully inserting at all. So I guess it's the exxos ram that's a bit out of spec in this situation (presumably necessarily so for the more common use case)

Edit: Did the other, both fit great now, RAM tests pass and YAART looking good too