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erichelgeson

What do I need to know about RAM for my SE/30?

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23 hours ago, Bendix said:

I am very sorry to hear it and feel bad, that I mislead you. I did a lot of testing in order to solve the wobbling module problem (actually a rubber band fixed it, but that cracked a few days later). While I tested all sorts of configurations (with the crt facing down to the table surface and the atx power extension cable) I was under the firm impression that between many nasty chime of death sounds I had heard the welcome chime with 64 MB on bank A only.

If everything works out with Gary's next delivery I will have 4x1MB spares, so in case you have not found anything then, send me a pm.

 

And vor what it's worth, I currently have 4x16 MB on bank A and 4x4 MB on B, so the larger modules on A seem to work.

No worries at all! I ordered the SIMMs before I read elsewhere that also Bank B needs to be occupied. I should have done a little more research! However interesting that it works for you with 4x16 in Bank A! For the wobble issue I planned to tin the contacts, as mentioned by @Trash80toHP_Mini

 

But really I should solve the root cause of Bank B not working on my Mac. I have quite a few 1 MB SIMM lying around, so I could easily fit it with a total of 8 MB. But right now it's limited to 4 MB. I'll test a bit with the 16 MB SIMMs when I get them before deciding what to do next.

Edited by blindowl

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I'm also wondering if cutting pressure sensitive vinyl used for signs as below might help? Applying it (them?) to the PCB acting as washer(s) could make up for the thinness in the mechanical interface topside?

_______________

|    O    |

|_____________|

 

Planar rubber-banding? :huh:

 

Edited by Trash80toHP_Mini
apparently I can no longer type or spell.

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On 6/15/2020 at 4:33 AM, trag said:

The problem is most likely the switch to Chinese circuit board manufacturers who only work in metric.

The specification for the thickness of the 30 pin SIMMs is .05", which is 1.27 mm.    Many of the new, cheap board manufacturers don't offer 1.27, only 1.2mm and 1.2mm as we are finding here and also in the ROMinator II is just too thin.

I'd imagine they make standard PCI thicknesses boards for edge card contacts? On a side note, which causes more problems with capacitance and such, PCI edge card/slot or EuroDIN connectors?

 

Back to the subject at hand: grimco.com/vinyl-basics-cast-vs.-calendered

Cast Vinyl (premium) starts as a liquid then is poured into a mold (aka a cast) and is approximately 2 mils thick.

Calendered Vinyl (Intermediate) is usually 2.5 mils to 4 mils thick.

 

Looks like a pair of Premium Vinyl "washers" might do the trick. There's a limited area, thin rectangular surface interface between SIMM and Socket. Vinyl's a bit "squishy" so more than two layers might be necessary for planar rubberbanding?.

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8 hours ago, Trash80toHP_Mini said:

I'd imagine they make standard PCI thicknesses boards for edge card contacts? On a side note, which causes more problems with capacitance and such, PCI edge card/slot or EuroDIN connectors?

 

PCI edge thickness, and later DIMMs and such, use .063" which happens to be 1.6mm, so it sits nicely on an even tenth of a mm.  Probably why .063 was chosen.

 

I'm not sure whether 72 pin SIMMs are .05 or .063.

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Finally I received the 16 MB SIMMs today. Unfortunately, but as expected, they didn't work in my SE/30.

 

Some of them wobbled in specific SIMM slots, but fit better in others. But they are slightly too thin. I tried to tin them on one side, and after that they fitted firmly. But if they have enough contact or not, I can't really tell.

 

I tested different combinations, none worked, but I got different starting chimes. Does anyone know more exact what the different starting sounds mean?

 

Test 1:

Bank A: 4 x 16 MB
Bank B: empty

Chime: 1.mp3


Test 2:

Bank A: 4 x 16 MB
Bank B: 4 x 1 MB

Chime: 2.mp3


Test 3:

Bank A: 4 x 1 MB
Bank B: 4 x 16 MB

Chime: 1.mp3

 

Chime 2 is the one I normally hear when I put any SIMMs in Bank B. Which is a bit weird. It's not playing the same chime with the 16 MB SIMMs in Bank B, as with anything else I've tried.

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Remember the wobbling ram simms I recommended from here: https://www.amazon.com/-/de/gp/product/B00FAYV3NO

 

Gary, the dealer behind the account named mally, sent me 3 replacements, all wobblers, too. By then he had realized, that the boards were not thick enough, and made his supplier produce new ones with the correct dimensions. One of those found its way to Germany today and it's a perfect fit, so this source is good again now.

 

I am writing a follow up here because as of now it seems that Gary is the only dealer, who ships to Europe, and at a very good price I might add.

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10 hours ago, Bendix said:

Remember the wobbling ram simms I recommended from here: https://www.amazon.com/-/de/gp/product/B00FAYV3NO

 

Gary, the dealer behind the account named mally, sent me 3 replacements, all wobblers, too. By then he had realized, that the boards were not thick enough, and made his supplier produce new ones with the correct dimensions. One of those found its way to Germany today and it's a perfect fit, so this source is good again now.

 

I am writing a follow up here because as of now it seems that Gary is the only dealer, who ships to Europe, and at a very good price I might add.

I also just bought some SIMMs from their ebay store and they work great so far.

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Just came upon this thread. Thank you all for your valuable input and advice.  I have 64MB of RAM on order from OWC, along with a ROMinator II that's on my desk waiting to be installed. I'll report back once everything's installed.

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Chiming in since I just installed more RAM in my Mac SE/30...

 

64MB of RAM (4 16 MB SIMMS) in Bank A worked, but I also had to have memory in Bank B, so I loaded it up with four 2MB SIMMS. The Mac recognizes the extra memory but I don't have the option to enable Mode32 (perhaps its an extension?) in the Memory Control panel. (I’m running System 7.5.5). RAM was ordered from MacSales. I initially tried having Bank A with the 8MB and Bank B with 64MB - but that did not work for me. Notably, there was a clearance issue with the larger SIMMM modules when putting them in Bank B. They would rub against the bottom the SE/30's metal chassis.

 

The Rominator II did not work for me.

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I picked up another SE/30 yesterday, and in this one the 16 MB SIMM's seem to work. 4 x 16 MB in Bank A and 4 x 256 kB in Bank B. As mentioned previously in this thread the ones I received were too thin so I tinned them on one side, but my other SE/30 didn't like them at all. But now I got use for them after all!

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