Taming the ROM in my SE/30!

[-SE40-]

What is the thickness difference exactly?
You have a caliper to measure?
Why are these thinner?

Is contact the real problem, or is the Rom itself defect?

 

[retr01]

What is the thickness difference exactly?

Steve at BMOW told me the Rominator II ROM stick is 1.27 mm thick. I surmise that the original Apple ROM stick for the SE/30 is thicker because it seats fine and works.

You have a caliper to measure?

No. I need to get a 6" composite digital caliper. That will help to confirm the thickness of those ROM sticks. It will be helpful in my tinkering adventures.

6 in. Composite Digital Caliper

Amazing deals on this 6In Composite Digital Caliper at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

The digital micrometer caliper is much more accurate! Someday, I'll get this.

Digital Micrometer

Amazing deals on this Digital Micrometer at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Why are these thinner?

Nowadays, about 1.2 mm is typical for PCBs but can be thicker depending on the purpose.

Is contact the real problem, or is the Rom itself defect?

The contact is the problem because the BMOW Rominator's PCB is not thick enough.

 

[-SE40-]

In that case you could also add some
ducttape layers to the back to thicken it up….



one or two layers maybe?

Just to see if that solves this issue.

​

 

[pfuentes69]

I had a similar issue... https://tinkerdifferent.com/threads/issue-with-rominator-ii-and-se-30-bad-contact.970/

My only stable solution was to add the layer of solder to the pads, combined with the @PotatoFi clips

 

[retr01]

I had a similar issue... https://tinkerdifferent.com/threads/issue-with-rominator-ii-and-se-30-bad-contact.970/

Cool. Thank you, @pfuentes69, for sharing.

My only stable solution was to add the layer of solder to the pads, combined with the @PotatoFi clips

Ah. I plan to try the solder approach if @PotatoFi's clips do not help to maintain good contact. I understand from @Drake earlier in this thread and your thread that soldering can be applied to SIMMs evenly by sweeping back and forth over one side of 30-pin contacts. I would like to practice that before I try it. I can do simple soldering, not complex.

 

[pfuentes69]

Ah. I plan to try the solder approach if @PotatoFi's clips do not help to maintain good contact. I understand from @Drake earlier in this thread and your thread that soldering can be applied to SIMMs evenly by sweeping back and forth over one side of 30-pin contacts. I would like to practice that before I try it. I can do simple soldering, not complex.

The technique is easy, but it's also easy to bridge the pads... I had a simasimac after the first try because I had a bridge I couldn't see without a good magnifier glass

 

[-SE40-]

You could try and practice first with an old sim?

 

[retr01]

As inspired by @-SE40-'s suggestion, I got the digital caliper for $7.99 at my local toy store. Yes, I said toy store because the Harbor Freight tool and supplies store is my toy store.

So, I measured the thickness of the modern BMOW Rominator II ROM 2 MB SIMM stick and the Apple ROM 512 KB SIMM stick for the SE/30 from 1988. As you can see, the following photographs confirm that Apple's ROM stick is thicker than BMOW's ROM stick, with the last picture showing the Apple ROM SIMM is about 0.1 mm thicker. I realize that the caliper is only accurate to one-tenth of a millimeter. Nevertheless, the measurements combined with @Drake, @pfuentes69, and many others and my experiences show that the thickness of the ROM SIMM matters for the ROM socket slot, new or old, on the SE/30 logic board since the SE/30 is very picky about the quality of connectivity between the ROM SIMM and the logic board.

 

[retr01]

The angles of insertion and seated positions do not differ between the stock and BMOW ROM sticks. Thus, the thickness of the modern ROM SIMM stick continues to be very important for the SE/30.

 

[-SE40-]

So, ……
This 0,1mm difference causes it not to work?
That could well be a little added solder tin.

Just go for it and try it,
as that seems to solve this matter.

If not, the solder can always be removed
again with solder litze/braided copper.

 

[Drake]

Im loving the documentation for this btw. Super handy for others researching issues.

 

[retr01]

That is for sure, @Drake! High five!

Cheers!

 

[retr01]

I went through it from the beginning to ensure I did not miss anything. I have made my checklist. I will update you as I progress.

I will start with the first section. Everything went well. Next, I will work on the second section.

Cheers!

 

[retr01]

The second section was a disaster! Four 16 MB RAM SIMMs in Bank A for 64 MB of RAM did not work out. A messed-up checkered screen appeared immediately after powering up my SE/30.

So, I am moving on to the third section to fill up Bank B with four more 16 MB RAM SIMMs for 128 MB.

A dab of hope and cheers!

 

[pfuentes69]

The second section was a disaster! Four 16 MB RAM SIMMs in Bank A for 64 MB of RAM did not work out. A messed-up checkered screen appeared immediately after powering up my SE/30.

So, I am moving on to the third section to fill up Bank B with four more 16 MB RAM SIMMs for 128 MB.

The same "bad contact" issues you find with the ROMinator can occur with modern RAM SIMMs. I have a set of 4x4MB SIMMs that my SE/30 doesn't like at all because are too thin.

 

[retr01]

The same "bad contact" issues you find with the ROMinator can occur with modern RAM SIMMs. I have a set of 4x4MB SIMMs that my SE/30 doesn't like at all because are too thin.

I agree that the modern RAM SIMMs can be too thin. After filling up Banks A and B to 128 MB, my SE/30 booted up to a happy Mac screen. And it just sat there, smiling. I waited for a few minutes for it to boot from BlueSCSI. No movement. It just sat there staring and smiling at me.

How long does the memory test take? Some say two minutes. I popped in my red emergency boot disk, and it booted fine. Hmmm.

A dab of hope and cheers,

 

[retr01]

 

[luminescentsimian]

2TB on an SE/30? Impressive

 

[retr01]

I picked up a 2 MB MacSIMM ROM by GGLabs just for fun while waiting for the 8 MB ROM SIMM from Garrett's Workshop. I was impressed GGLabs made sure the PCB thickness of the ROM SIMM was the same as the stock ROM SIMM. I confirmed it is thicker than the anorexic BMOW's Rominator. So, I installed it in my SE/30 to see how it behaves.

 

[retr01]

Unfortunately, when I powered on my SE/30, I was greeted with this screen of checkered patterning. I swapped back to the stock ROM SIMM, which booted without issues. I reseated the GGLabs MacSIMM, and the same checkered patterning appeared.