No boot after changing to Exxos 4 MB simms on STE

[Magnus]

Hi!

I recently bought a 4 mb ram upgrade for my STe from Exxos. The machine has 2mb installed today and I upgraded it to TOS 2.06. All has worked well. I also have a new Exxos PSU installed and all voltages are correct under load (5.16V & 12.24V).

When installing, I cleaned all contacts on the simm chips and the contacts in the simm holders on the motherboard with isopropanol. The chips are seated correctly and all looks good.

However, when I power on the Atari it won’t boot at all. Only a black screen. I tried installing the old Simms again and it works as normal.

Is there anything I am doing wrong or forgetting? What could cause a problem like this?

Would really appreciate any help!

[exxos]

The problem with the STE's are the sockets normally. Most simms actually damage the sockets (making the contacts wider than the max tolerance on the socket) which means other simms like mine which were made "to spec" make bad contacts in the sockets. This is why I ended up flowing solder on them to make them even wider to combat the issue.

Do any of the simms seem a loose fit ? Normally they fit fine in unused simm sockets, the ones which had simms in before are the ones which will have issues most likely. Will the STE boot with 2MB (2 simms installed ?)

[Magnus]

Thank you for your reply!

Actually, there were 4 simm chips already installed but the machine only registered 2 MB when doing the memory test as it boots up. Maybe because of faulty sockets?
The machine won’t boot with only 2 chips installed, only when all four are installed.

All the RAM chips (both old and new) seem to fit well and do not seem loose though, but I assume it only takes one or a few pins to be loose in a socket to cause problems?

It does sound like maybe there is a problem with one or two of the sockets, or do you think it might be something else?

[exxos]

Do you get 1MB when 2 simms installed ? Your simms may not be 1MB ones...

[Magnus]

It won’t boot at all with only two Simms installed. Only a black screen. Tried placing the chips in slots 1 and 3 as well as 2 and 4 respectively, but no boot.

Also, tried other combos, 1&2, 3&4 etc but still only a black screen. I tried with both with your new chips and the old ones.

[exxos]

Most likely you need to change the sockets then.. The STE may even have some other fault, but its normally the sockets.

[Magnus]

New sockets it is! Will order some soon. Thank you for your help Exxos!