Nasty Time Bombs Removed Just In Knick Of Time!!

[macuserman]

Whew! Cutting it close on this Macintosh II!

 

[KGLlewellyn]

TWO Maxells in one Mac...I would not have wanted to see the results if both went off. Oof.

Nice catch!

 

[Johnnya101]

Wow, that was close!

Sidenote: Why is it that some people seem to only find Maxells, and some almost never find them? Was it regional? In probably the 30+ Macs I've come across, I have only found one intact one...

 

[macuserman]

Wow, that was close!

Sidenote: Why is it that some people seem to only find Maxells, and some almost never find them? Was it regional? In probably the 30+ Macs I've come across, I have only found one intact one...

Hmm I've found quite a few I have some machines that did explode already. This is my first macintosh II not sure if I'll keep it or not but I want to play with it at least first and I couldn't wait to get those batteries out when I saw them.

 

[Johnnya101]

Wow, that was close!

Sidenote: Why is it that some people seem to only find Maxells, and some almost never find them? Was it regional? In probably the 30+ Macs I've come across, I have only found one intact one...

Forgot the edit was removed, so ill reply. Meant to say ive only ever found one maxell.

 

[Byrd]

One is bad enough, two Maxells - that's enough to start a small turf war!

I've come across mostly Maxells in early 68K machines, but picked up a B&W G3 recently which had a Maxell.

 

[macuserman]

Hmmm well I may have spoken to soon about saving it just yet lol. I am getting zero signs of life out of it when I try to power it on.

 

[macuserman]

Anyone have a test procedure or at least a pinout for the Macintosh II PSU? Be nice to first figure out if it's a PSU or board problem. Board looks really good though so I'm betting PSU.

 

[bibilit]

Have you got a pair of brand new batteries ? The Macintosh II series will need ones to kick the boot process (there's a trick shorting two wires on the PSU connector though)

 

[macuserman]

Have you got a pair of brand new batteries ? The Macintosh II series will need ones to kick the boot process (there's a trick shorting two wires on the PSU connector though)

Ohhh hmm nope, I have some batteries, but didn't put them in this is my first macintosh II that I've played with so I was not aware that they required the batteries to boot. On machines I've used in the past that required it, they would usually power on but just not boot, this isn't doing anything at all.

 

[macuserman]

Ohhh hmm nope, I have some batteries, but didn't put them in this is my first macintosh II that I've played with so I was not aware that they required the batteries to boot. On machines I've used in the past that required it, they would usually power on but just not boot, this isn't doing anything at all.

Just put fresh batteries in it but still nothing so unfortunately that wasn't my issue.

 

[joshc]

Your board has the original electrolytic SMD capacitors, it needs to be recapped.

These Mac IIs also have a tendency of problems with their start-up circuit which is documented here: https://www.downtowndougbrown.com/2015/03/explanation-of-the-macintosh-iiiix-power-onoff-circuit/

My Mac II wouldn't start even after it was recapped because of a bad trace in the start-up circuit.

 

[macuserman]

Your board has the original electrolytic SMD capacitors, it needs to be recapped.

These Mac IIs also have a tendency of problems with their start-up circuit which is documented here: https://www.downtowndougbrown.com/2015/03/explanation-of-the-macintosh-iiiix-power-onoff-circuit/

My Mac II wouldn't start even after it was recapped because of a bad trace in the start-up circuit.

Ugh yeah I was thinking I'd need to do that, I guess I need to find a list of caps to order or sit and look them all up on my own but rather just order them and have them on hand before disassembling.

 

[macuserman]

Also not quite sure how to safely remove the adapter to get at the caps and areas around/under it for inspection.

 

[macuserman]

I know you can get a puller type device or at least I've seen pictures of them for the original CPU chips by itself, but these big adapters no idea how that would even work on one, hate to damage it trying to remove it.

 

[joshc]

That one just pulls up by hand, it’s inserted directly into the CPU and MMU sockets. Just be gentle with it.

Cap guides:

Rev A: https://recapamac.com.au/macintosh-ii-a/

Rev B: https://recapamac.com.au/macintosh-ii-b/

 

[macuserman]

That one just pulls up by hand, it’s inserted directly into the CPU and MMU sockets. Just be gentle with it.

Cap guides:

Rev A: https://recapamac.com.au/macintosh-ii-a/

Rev B: https://recapamac.com.au/macintosh-ii-b/

Got it I'll give that a try when my caps come in. On another note what's the easiest way to tell if this board is FDHD already? I couldn't seem to find a list of the chip numbers just which chips needed to be changed.

 

[joshc]

It's a case of new ROMs and changing the IWM chip to a SWIM chip.

More details on the FDHD upgrade here:

Macintosh II ROM Replacement

I'd like to upgrade my Macintosh II to FDHD, I have a SWIM chip (to replace the WIM chip), but don't know how to burn the ROMS. The upgrade process I'm trying to do is described in the book: "

retrocomputing.stackexchange.com

Also more detail here

upgrading ROM for Macintosh II?

hi all, is it possible to replace the ROMs of the Macintosh II with 800k floppy with the version of the one with FDHD? from this 1987-12 - 9779D2C4 - MacII (800k v2).ROM to this 1988-09 - 97221136 - Mac II FDHD & IIx & IIcx.ROM thanks!

68kmla.org

Post a photo here of your chip and someone will be able to identify if its an IWM or SWIM.

 

[macuserman]

It says IWM next to the chip but I suppose that doesn’t mean it hasn’t been changed I was hoping it was already modded because the floppy drive looked like a 1.44mb drive.

 

[KGLlewellyn]

Wow, that was close!

Sidenote: Why is it that some people seem to only find Maxells, and some almost never find them? Was it regional? In probably the 30+ Macs I've come across, I have only found one intact one...

I get what you mean. I've never seen one, and I've collected a lot of machines over the years in NW US and UK.