Levco MonsterMac with SCSI and lots of dirt

[mst3k]

I just acquired a Mac 512k with a Levco MonsterMac plus SCSI.
I was actually surprised at the size of the metal box that holds the disk drive and power supply.
It takes up the entire right side of the machine and barely fits. It is quite heavy and bolted into place with two pressure plates and a screw.
I was also surprised to find an Apple Quantum 80S SCSI drive next to the SCSI power supply inside the metal box structure.
The machine boots and works but the SCSI drive does not.
The Levco SCSI draws power from the Analog board with some clips and the SCSI interface plugs directly into the Levco board which plugs into the 512K logic board.
I've been trying to learn as much as I can about these 'monsters' but there really isn't a lot of information that I could find. I do believe this is a later version because it has the version 2 and 2.1 ROMS. But, again, I have no idea...
The 512k shows 2mb of RAM after booting. The internal floppy works, but the external floppy port does not. I am booting the system with my Floppy Emu from the internal FDD port. The Floppy Emu is not recognized on the external port. I read somewhere that the external FDD is hijacked or disabled by the Monster Mac, but I don't know if that is true. There is also a SCSI port cable that runs from the internal HDD out thru a hole in the back of the case.

My short term plan:
Clean this thing up.
Recap the analog board.
Make sure the main Levco board works properly.
Go after the SCSI.

Any advice or experience with these things would be appreciated.
Thanks!

 

[olePigeon]

That's pretty similar to the HyperDrive. Cool looking upgrade. Hopefully when you get it working it'll boot with the funny Monster Mac instead of the Happy Mac.

 

[eharmon]

Looks like a 68HC000 on board, interesting. I wonder if they needed to cut power consumption for all that extra draw!

 

[mst3k]

I've recapped the analog board and reflowed the connector points on the back but I keep getting this display failure (see picture). It works fine for a bit and then jumps out to this grayed screen with lines. Unplug and let it sit and it fires up again. Any idea where to look on the AB for the issue? Thank you

 

[demik]

Sounds like a dry solder joint or something similar (temperature related)

BTW, Can you dump the ROMs if possible ?

 

[mst3k]

Sounds like a dry solder joint or something similar (temperature related)

BTW, Can you dump the ROMs if possible ?

I'll get out the magnifier and go back over the AB and reflow everything.

I found the version 2 ROMS on Archive.org:

MonsterMac v2 ROM : Levco : Free Download, Borrow, and Streaming : Internet Archive

ROMs from the MonsterMac v2 board. Dumped from a board in a Mac 512 logic board.

archive.org

Not sure if that is what you are looking for, but I can try and dump these too.

The SCSI isn't working at all. I get power from the AB to the Levco PS. It runs the Levco fan and spins up a HDD, however, I can't get anything to appear on the SCSI bus. I'm not sure if the SCSI board is haywire or what. There is a suspect cable I'm going to take a look at...
There are two megs of working RAM and the machine boots easily to 6.08 or 7.0 from my CayMac HD20 or the Mac EMU, but no joy yet on the SCSI.
I have another 512 which I've tried with the MonsterMac board and it works, so I might just use that AB until I can get the SCSI working.

That's pretty similar to the HyperDrive. Cool looking upgrade. Hopefully when you get it working it'll boot with the funny Monster Mac instead of the Happy Mac.

However, No funny teeth yet...

 

[Juror22]

However, No funny teeth yet...

That's what I found with mine - no zany startup, and the MonsterMac just worked, providing the additional memory. I have a revision 'D' board with the same revision ROMS and I suspect that only early revisions of the board/ROMS had the fun startup and that it was cleansed from the later versions (?). I don't have the SCSI add-on, so this is really cool to follow.

 

[mst3k]

It's Alive!

The 512 is booting from an external Apple 20 HarddiskSC with an Apple Quantum 80s HDD using Mac 7.5 and the Levco SCSI adapter (module?). 7.5 is not usable with just 2mb, but it boots (until it doesn't).
Going to set up and test a 6.08 drive now that I know the SCSI external cable works.

Once that works, I'll move on to the internal SCSI connection. I think there is a cable problem. It's pretty ragged around around the connector and the cable appears to have a break (or two).

Not sure why BlueSCSI and ZuluSCSI drives don't work on the external cable. I'm using external power and the Levco SCSI adapter (module?) seems to 'see' them, but neither will boot. They're both the 'external' versions that connect to SCSI port. I've tried 6.08 and 7. When I switched to the Apple External SCSI drive with an Apple branded HDD everything started working.

Also, check out that other 'monster' in the upper right of the first picture: a Seagate ST225N that I pulled from my external drive. Boo!

 

[Huxley]

I found a similarly-equipped MonsterMac a few months ago! I haven't had time to play with it yet, but your post is inspiring me to pull it out of storage and see what shape it's in. If nothing else, I'm quite curious to see if my ROM version matches yours. Fun project!

Huxley

 

[mst3k]

I found a similarly-equipped MonsterMac a few months ago! I haven't had time to play with it yet, but your post is inspiring me to pull it out of storage and see what shape it's in. If nothing else, I'm quite curious to see if my ROM version matches yours. Fun project!

Huxley

You know what? This is a fun project!

Here's a picture or two of my cable problem. I've never tried 'knitting' one of these before. Has anyone seen something like this or is this custom?
I'm game to try and build one, but if something like this already exists, I'd rather get out my wallet.

Anyway, the 6.08 installed perfectly. The 512 boots from the external Apple SCSI drive and my endorphins are flowing...

 

[mst3k]

Just when I thought I had a conquest? Now I'm on the floor staring at the ceiling....
Put everything back together (without the working internal SCSI) and this happened:



I've checked the voltages. All good.
I've checked and reseated all of the memory chips. Same result but a slightly different checkerboard.
I've cleaned everything again. Same result.
I've tried my other 512 board in this machine. Works fine.
I've tried the Levco board in my other 512 and get a similar checkerboard.
From what I've read, if the voltages are good, this is a memory issue?

There is no joy in Mudville...

 

[mst3k]

Hmm.
I've tried the Dead Mac Scrolls fixes for this problem:

Probable diagnosis: One of the pin headers isn't making contact.
Solution: For a temporary fix, reseat the boards at location ES to E8
on the 512Ke logic board . For a permanent fix, replace the OEM
pin headers with two 64-pin IC sockets. Reconnect the two boards
with a 64-pin socket header.

Probable diagnosis: The problem is in the wiring harness.
Solution: For a temporary fix, reseat the wire between C24 and R32 at board location 02 to E2 on the Macintosh logic board. For a permanent fix, solder the wire in place. If that doesn't do it, see the next entry.

Probable diagnosis: The reset lever on the programmer's switch is making contact with the reset button on the logic board.
Solution: Check/reposition the programmer's switch . If necessary, trim and shorten the shafts.

All the memory 'issues' I have found described on these boards usually generate a Sad Mac, not a checkerboard.
It's not an analog board issue (voltages correct and tested with a different board).

Any thing I'm missing here? Did I fry the CPU somehow?

 

[mst3k]

Progress?
Now it looks a bit more 'traditional' and includes interesting popping sounds from the speaker.

 

[cheesestraws]

does anything happen if you press the reset button?

 

[mst3k]

does anything happen if you press the reset button?

Reset button does nothing...except, occasionally the checkerboard will be in a screen roll and the reset button will stop the roll.
Other than that, if the checkerboard image is stable, the reset button does nothing (and it is stable 9 times out of 10 on startup).

 

[mst3k]

Still no joy.
I found someone online who had a similar problem and pegged the 6522 VIA chip as the culprit.
The saga continues.

 

[mst3k]

The Brothers Marx aren’t cooperating.
I’ve seen these with the 7 Dwarfs, not sure if the Marx Brothers are rare or common.

 

[Juror22]

I’ve seen these with the 7 Dwarfs, not sure if the Marx Brothers are rare or common.

I've got the Marx brothers as well - I think I've seen the Dwarfs on earlier boards(?), but I also thought that I should mention that the 512 board that mine was attached to had a bad (leaky) axial cap, which I still need to make time to fix.