Help wanted: Revitalize or replace Macintosh II RAM sockets

[rdmark]

My fairly recently acquired Macintosh II had 8 functional 30-pin RAM sockets of the SIMM kind when I first got it, and it ran happily with 1 x 8 MB sticks for a few months. However, the other day it started suddenly death chiming on startup, and removing the B Bank sticks is the only way to reliably get it to boot again.

If I absolutely soak the sockets in contact cleaner and populate the B Bank again, the system will work for an hour or so, but then start death chiming again. Therefore, my conclusion at this point is that the B Bank sockets simply have really poor contact with the RAM sticks. When I got the machine, only the A Bank was populated with RAM, so I assume that the B Bank was left empty for the machine's 30+ years of service, which I believe gives moisture and grime all the opportunity in the world to oxidize the contacts.

At this point, I've spent hours cleaning, scrubbing, scratching, and swearing, using plenty alcohol and contact cleaner trying to get both the socket contacts clean, as well as the contacts on all my RAM sticks. My fingertips are sore as I type this. I'm at the point where I'm considering swapping out the sockets altogether.

What I'd like to ask this community's advice are:

1. One, is there anything else I can try to revitalize the stock SIMM sockets?
2. Do you know of a source of Mac II compatible sockets? My searches have yet to yield success.

 

[Kai Robinson]

PEConnectors has a load that would be suitable: https://www.peconnectors.com/memory-sockets-simm-dimm/

 

[YMK]

One, is there anything else I can try to revitalize the stock SIMM sockets?

You can pinch the contact fingers a bit with needle noise pliers to increase the pressure on the SIMM pads.

 

[rdmark]

PEConnectors has a load that would be suitable: https://www.peconnectors.com/memory-sockets-simm-dimm/

Thanks. I ordered a couple of the one product that seemed the most likely to fit. Will report back here when I get to try it!

 

[rdmark]

You can pinch the contact fingers a bit with needle noise pliers to increase the pressure on the SIMM pads.

This approach didn't quite work with this particular type of slot. Each of the contacts are resting in a recess in the plastic, and if you pinch them they pop out of their recess and end up obstructing the slot. There's no leeway to bend them in either direction. They're either inside the recess, or outside in the slot.

 

[Kay K.M.Mods]

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I replaced the RAM sockets for the same reason.
I wanted to try something else and included a ROM test, but I replaced the 2-rows with 1-row sockets and replaced 8pcs.

 

[rdmark]

I can happily report that the 30 pin SIMM Socket Metal Latches product from Phoenix Enterprises work great in a Mac II, with some minor modifications. The spacing and layout of all the pins line up perfectly, however, the two plastic prongs on each end are of the wrong shape for the holes in the Mac II logic board, so I had to carve them down with a hobby knife. Two prongs broke off while doing this, which could probably be avoided with better tools. But the sockets still seem to be securely attached regardless.

Now, to my dismay, the exact same pattern of RAM test failure chimes remained the same after the modification. This made be break out my SE and stole the 4 known good 30-pin SIMMs from that machine, and plopped them into the Mac II. Works perfectly. So it seems to have been a matter of faulty RAM after all. I was testing with two sets of 4 other SIMMs, and it seems like one or more of the modules in both sets had gone bad in both in the span of a few days. Time to procure some more 1MB modules!

At least, my Mac II has some shiny new metal latch SIMM slots now, perhaps preempting a future where the plastic latches would have broken off.