MAC SE Upgrade help!

[phillip B.]

I have a mac Se and due to the fact that it would only accept 800k floppies I bought a superdrive and a new motherboard with the upgrade Rom chips. I swapt the ram and battery off the old motherboard onto the new one And hooked it up and turned on the mac but as soon a the screen warmed up all i could see was black and white lines. the little happy mac would appear but thats all it would do.

does anyone know what I did wrong?

I put the old motherbored in and it works fine

but i would like to use 1.44 floppies

Please help !


-Phil

 

[DZ/015]

does anyone know what I did wrong?

Most likely, nothing. Try rebooting a few times. You may get it to work.

However, it sounds like the logic board you purchased is no good. Take a look at the capacitors on the board. They may have an oily residue around them. If so, they need to be replaced. This is the most common failure mode of the old compact macs, but not the only one.

If you aren't afraid to solder, try searching for "simasimac" on the web. You will learn how to correct the issue.

 

[phillip B.]

I looked at the capacitors and they all seam to be in good working order.

Could it be possible that the rom chips are fried?
I can switch back and forth freely with my old rom chips and both boards will boot.

is their any way to repair a rom chip. I mean since i can't really go and buy new ones. its a pretty big bummer too since i bought the mother bored just for the rom chips.

oh he is a picture of the screen I hope it might help

thanks again,

-Phil

 

[MacTech68]

The first model SEs didn't use the surface mounted electrolytic capacitors that leak and corrode tracks. These appeared on the SE30 (68030 CPU) and "Macintosh Classic" & "Classic II" and most other PCBs since that time.

For interest's sake, the offending caps look like this.

The SE and SE FDHD motherboards require either a jumper or resistor to be changed/cut in order to handle certain types of RAM. You also need to swap the IWM (Intergrated Woz Machine) chip in order to handle HD floppy drives.

Check to make sure the ROM's pins are straight and not bent under the chip when inserted.

I'll see if I can indentify the correct numbers stamped on the ROMs and IWM for both the SE & SE FDHD and the resisitor/jumper settings and get back to you.

EDIT:

The original SE Motherboard used the resistors.
A resistor is installed at R35 for 1MB
A resistor is installed at R36 for 2MB

The later boards used a rather confusing jumper.
For 1MB install the jumper over the 1MB pins
For 2MB install the jumper over the 2/4MB pins
For 2.5MB remove the jumper completely
For 4MB remove the jumper completely

For the HD floppy to work, you must use system 6.0.3 or greater.

The FDHD Chips are as follows:

SWIM - marked as 344-0062 at location D8
ROM-Hi - marked as 342-0701 at location D6
ROM-Lo - marked as 342-0702 at location D7

I don't have the markings for the 800K versions.

Hope that helps.

 

[phillip B.]

I have a resistor at R35 and R36 Since I only have 1MB of ram do I remove R36?

-Phil

 

[MacTech68]

I have a resistor at R35 and R36 Since I only have 1MB of ram do I remove R36?

-Phil

The SE motherboard always used to give me grief. As far as I can determine, if you've only got 1MB, leave R36 in place.

How about that SWIM chip and the ROMs ? Are they the correct numbers?

 

[phillip B.]

yeah they are all the same as the one named above

-Phil

 

[MacTech68]

Hmmm... looking at the pic, your screen seems to have a "Happy Mac" icon in the middle. Does this mean the machine boots but still has the vertical stripes?

If so, it looks like a memory addressing fault, but where to begin. Though IIRC, this happens on both boards only when using the FDHD ROMs and SWIM chip, correct?

If so, are you using the same RAM on both boards? If so, then I'd suggest going down to the minimum configuration of RAM that you can, using just 2 memory SIMMS and then swap to the other two memory SIMMs and see if the problem persists.

Not much more I can do, except to suggest powering on the machine with no peripherals connected to see if the problem goes away, and to double check the ROM chip pins are not bent and are clean (they do tarnish to a nasty black color). If they are dirty, a light rub (carefully and gently) with the finest sand-paper you can buy might clean them up but be careful of pins that wobble at the 'shoulder' where the pin enters the chip. A tiny dab of solder on the shoulder can help to strengthen it if it's close to breaking.

Good luck!