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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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