Mac 512k error code 014120

[gallium34]

Hi,

I have recently been charged with repairing a Mac512k.
On powering up i get a beep followed by the 'Sad Mac' and an error 014120
I think this is a ROM issue, is this correct?

There is another site "http://members.tripod.com/elfen_magix/sadcodes.html"
which suggests that this is, and i quote '014120: Started after upgrade; Voltage too Low, adjust voltage to +5.0v'
However, i have checked the 5v and 12v lines and they are fine.

If this is a ROM issue, can the ROM's be purchased anywhere.

First post, please be gentle

[MacTech68]

Hi, and welcome to the forums.

Your error code does indeed appear to be a "ROM Test Failed" code.

http://support.apple.com/kb/TA46376

However, since the ROMs are socketted, it could simply mean the ROM chips require re-seating, or worst case, a light cleaning of the pins and socket followed by re-seating.

Have you been able to view the motherboard? What are the 341-xxxx numbers printed on each ROM and what type of floppy drive (400K or 800K) does the machine have?

If your unsure of the drive type, a pic of the rear of the drive will make identification very simple.

[gallium34]

Hi MacTech68,

Many thanks for replying to me.

I have re-seated the ROM's after cleaning the contacts, no joy I'm afraid.

The Drive is a Sony OA-D34V-22, which is a 400k drive i think.

The ROM's are:

Hi ROM: 543 VH 9091 - 23256-1106
Lo ROM: 542 VH 8958 - 23256-1105

Are these available to purchase anywhere? I do have the capability to program some EEPROM's to match if i could get the hex files that are on these ROM's. Although, I haven't yet looked at the datasheet for the Mac ROM's to see if i can get compatible EEPROM's, so this may be a non-starter.

Thanks again.

----------

Sorry for the double post.

The 34 numbers on the ROM's are:

342-0220-B
342-0221-B

Should have read the reply properly before responding!

[MacTech68]

Originally Posted by gallium34

Hi MacTech68,

Many thanks for replying to me.

I have re-seated the ROM's after cleaning the contacts, no joy I'm afraid.

The Drive is a Sony OA-D34V-22, which is a 400k drive i think.

The ROM's are:

Hi ROM: 543 VH 9091 - 23256-1106
Lo ROM: 542 VH 8958 - 23256-1105

Are these available to purchase anywhere? I do have the capability to program some EEPROM's to match if i could get the hex files that are on these ROM's. Although, I haven't yet looked at the datasheet for the Mac ROM's to see if i can get compatible EEPROM's, so this may be a non-starter.

Thanks again...

The 34 numbers on the ROM's are:

342-0220-B
342-0221-B

Partially my bad for referring to "341-xxxx" ROMs instead of "342-xxxx" ROMs.

Yes, that Sony drive is a 400K.

My final tip would be to check the ROMs are in their correct sockets. It's un-intuitive, but:

"ROM-LO" is "342-0221-B"
"ROM-HI" is "342-0220-B"

Finally, IIRC the ROMs for use with a 400K drive are equivalent to 27256 EPROMs. I'm not sure if Apple changed the pinouts slightly - many vendors did that to prevent use of standard EPROMs. You'll probably only get 27256s second hand these days. As for the code - good luck.

You may do better trying to get a Mac 128K or Mac 512K with 400K drive. If a replacement machine has an 800K drive, the ROMs will be 128K (27512 equiv ?).

As for getting the ROMs, use the 342 part numbers to search for them.

Also note that the "-B" ROMs are only compatible with the Sony OA-D34V-22 or OA-D34V-02 drive. Earlier drives "OA-D34V" used the "-A" ROMs.

[gallium34]

Thanks for all your help with this MacTech68.

I have found the code for the ROM's here:
http://www.synack.net/~bbraun/roms/
Might be useful for someone else.

Not having much luck finding the pinouts for the original ROM's though. Have to hone my googling skills

I'll let you know how i get on.

[MacTech68]

Originally Posted by gallium34

Thanks for all your help with this MacTech68.

I have found the code for the ROM's here:
http://www.synack.net/~bbraun/roms/
Might be useful for someone else.

Not having much luck finding the pinouts for the original ROM's though. Have to hone my googling skills

I'll let you know how i get on.

Again... correction to my previous. Seems the ROMs are closest to a 27256 EPROM. Lift Pin 1 and tie the ROM's Pin 1 to Pin 28 (after it's programmed).

However, it appears that a 27512 is a direct equivalent.

[tdiaz]

Lift pin 1 or load the contents twice, once at 0000 in the buffer, and again at 020000, or 131072, if the programmer shows the memory space in decimal.

Basically, the address where you see zeros again.

Then if it uses the high bank, it will still load the same code.

I used 27512s in there a lot, too.

[MacTech68]

Originally Posted by tdiaz

Lift pin 1 or load the contents twice, once at 0000 in the buffer, and again at 020000, or 131072, if the programmer shows the memory space in decimal.

Basically, the address where you see zeros again.

Then if it uses the high bank, it will still load the same code.

I used 27512s in there a lot, too.

Thanks, tdiaz - I've never needed to use an EPROM on an early Mac before - I did use heaps on the Apple II's and their interface cards, of course.

I still have my UV eraser around here somewhere.

[gallium34]

Wow,

This is way more info and help than I was expecting. Thank you so much MacTech68 & tdiaz.
I have some 27512's on order. so will let you know how i get on. I think i'll try and load the code twice at the two memory locations.

Thanks again.