Macintosh SE issue

Hi,

I have a Macintosh SE who used to work fine; about an year ago, after some years without to use it, I fired it up, and, tah-dah! I got this "barcode" screen:



Somebody told me about faulty caps or RAM... so I replaced all caps (no changes), and I bought some RAM modules.

Since RAM modules for Mac were offered on eBay for a ridiculous price ("hey, it's Apple, lets take the fair price and apply a 3x or 4x ...") I bought other RAM cards, these one. They were guaranteed as working and the price was low.




I had to make a little mod, since there were caps mounted on the back side, making the cards too thick to fit; I modified two of them (bank 3 and 4) moving the caps from the solder side (upper right module) to the component side.




This is the result:




Something changes, but it's still far from working.

Do you think I should buy another kind of RAM ?

Well for starters you are not limited to only 256kb 30 pin SIMMs. It will take larger sizes but your hard limit is 4mb. 1mb Toshiba SIMMs are pretty much $5 for a set of four these days.

Second, verify that your +5 and +12 are present and healthy. Cap issues are uncommon in the SE because unlike the SE/30 the SE used traditional through-hole components which are a bit more durable.

How much rams had you i the first place, and how much was added ?

The Macintosh SE cannot accept ram without a small Logic Board mod.

The first units were supplied with a resistor that must be removed, second generation had a small jumper to do so (all close to the ram slots)

I agree with NeXT, capacitors are not a common issue...

bibilit said:

How much rams had you i the first place, and how much was added ?

The Macintosh SE cannot accept ram without a small Logic Board mod.

The first units were supplied with a resistor that must be removed, second generation had a small jumper to do so (all close to the ram slots)

I agree with NeXT, capacitors are not a common issue...

Click to expand...

I didn't add RAM, just replaced the four SIMMs with fresh ones. I don't know if the ones I bought were ok; the seller told they were, but I haven't any other system that accept 30 pin SIMMs, so I can't be sure. However the screen changed from vertical to horizontal bars, so RAM probably is the issue...

I knew caps probably weren't the problem; I read a lot about caps and SE/30; but it was an easy shot in the dark, so I replaced them.

I found a replacement SIMMs for few bucks, so I bought it; it will take some weeks to arrive here in Brazil...

I just realized you are in Brazil.

In that case I'm really sorry for saying the ram could be found cheap.

The Macintosh SE cannot accept ram without a small Logic Board mod.

Click to expand...

He's referring to either a jumper or a set of resistors, depending on what revision of the board you have.

To upgrade to 2 MB, remove all the 256 KB SIMMs, being careful not to damage the sockets. Replace the ones in Bank A with a pair of 1 MB SIMMs. If you have the resistor motherboard, remove R35 but leave R36 in place. If you have the jumper motherboard, put the jumper in the 2/4M position.

To upgrade to 2.5 MB, remove the 256 KB SIMMs from Bank A, being careful not to damage the sockets. Replace these with 1 MB SIMMs. If you have the resistor motherboard, remove R35 and R36. If you have the jumper motherboard, remove the jumper.

To upgrade to 4 MB, remove all four 256 KB SIMMs and replace them with 1 MB SIMMs, being careful not to damage the SIMM sockets. If you have the resistor motherboard, remove R35 and R36. If you have the jumper motherboard, remove the jumper. (Oddly, you do not set it to the 2/4M setting.)

Click to expand...

NeXT said:

I just realized you are in Brazil.

In that case I'm really sorry for saying the ram could be found cheap.

Click to expand...

Well, I use to buy on eBay, no way to found parts here in Brazil for a fair price. But often the problem with eBay is the shipping cost, and the custom duty fee.
However I found a replacement for 6 US$, plus shipping 12US$ (when I looked for Apple Mac RAM in the past I only found 4 x SIMMs for 30 US$ or similar, plus shipping).
I've got them; waiting for the parcel.

NeXT said:

He's referring to either a jumper or a set of resistors, depending on what revision of the board you have.

Click to expand...

Thank you! Of course I have the resistor model (nothing is easy, LOL), but since I bought an 1Mb ram replacement, there's no need to fire up the solder iron.

-- Giovi

I got the new RAM set, declared as "tested, good". I tried it and this is the result.



If I change the simm order, swapping the simm #1 with the simm #3 and the simm #2 with the simm #4, I get another screen pattern: the black, vertical lines move from the bottom of the screen to the center.



Another bad RAM set?

Since it was easy and fast, I opted for a shot in the dark and replaced the two 74LS245 close to the RAM banks. No changes.

I know this may be a stupid question but... Do you have a boot disk? I only ask because you didn't say it was a super drive model.

I have a boot disk and an external bootable hard disk.

It worked fine until the day it died

I'm not an expert on the SE hardware, but I would suspect there's a broken solder joint, trace or a bad IC somewhere on the motherboard. It's pretty unlikely that all of your memory sticks are bad.

GiGaBiTe said:

I'm not an expert on the SE hardware, but I would suspect there's a broken solder joint, trace or a bad IC somewhere on the motherboard. It's pretty unlikely that all of your memory sticks are bad.

Click to expand...

Maybe, but I suspect it's not a broken solder. Every RAM set returns a different behavior (pattern on screen). I found and bought a lot of 35 ram sticks sold as working for few bucks; I'm waiting for them... This way I will pretty sure it's a RAM issue, or it isn't.... Will tell you later.

Don't rule out bad solder connections, they can look fine but have microscopic cracks that cause failure. Really old solder tends to get brittle and any mechanical stress can cause failure of the joint.