A Macintosh IIci and a Red Maxwell

[sadmanonatrain]

Hello all,

Earlier this week a Macintosh IIci arrived from Ebay that was described as having 'some corrosion on the power supply and motherboard'.

I stripped the Mac down to check the the logic board's damage: a red Maxwell battery had leaked (thankfully the Mac was used on its side so the case bore the brunt of the acid damage) in such a way that the battery holder became detached from the logic board.

Other damage includes a few corroded components such as the ROM pins nearest the battery.

Also included was a IIci cache card, an E-Machines video card and a Farallon Ethernet card.

As a matter of course I washed the logic board and recapped it with eight 47uf 16v and two 10uf 16v capacitors.

When I turn on the Mac the power supply kicks in and the hard drive spins up. The green light on the logic board comes on.

But there is no chime! I think the battery leakage could have damaged the ROM.

I have tried a SE/30 (chimes of death) and IIfx (normal chime then chimes of death) ROM in the IIci but it did not work.

I cannot get anything to show up on the screen.

Any suggestions would be much appreciated!

 

[paws]

Those two oscillators(?) in the top right of the photo don't like at all right.

 

[techknight]

Well especially the RTC IC next to the watch crystal. Will that cause a no-post? Probably not. But the main clock oscillator would!

Your going to need to remove and replace that oscillator, Or remove it at least, as a good chunk of the ROM databus runs underneath it.

 

[sadmanonatrain]

Hello all,

I removed the oscillator, a Saronix 9029 50MHz, then and tested the logic board. Without the oscillator the IIci does not chime/chimes of death no matter what ROM SIMM is present.

So I put it back under the assumption that it could be OK and any damage is only external.

Could the corrosion on the pins of the pictured ROM be enough to make the IIci not POST?

Thank you!

 

[volvo242gt]

Out of curiousity, when you were testing the board without the ROM SIMMs, you did have the jumper installed next to the SIMM slot, right? If that's not installed, the computer will just sit there, doing nothing. I'm not 100% certain what would happen if the jumper is installed and a ROM SIMM is in the slot. It should ignore the slot, but, if the jumper was present at all times, that might be why the computer did the chimes of death with the various SIMMs.

Re: the corrosion, it might be a good idea to get some deoxit and clean the pins, just to see what happens. Who knows, it may just come back to life, in which case, you just need to get a new battery holder, or run some wires to a triple AA battery holder and use 1.2 volt rechargeables in that.

-J

 

[genie_mac]

Hi,

there seems to be a lot of corrosion around D8 (component labelled A6, a high speed diode IIRC). I suppose it's time to get the multimeter out and start checking for continuity, shorts, opens etc.

Also is the area in the picture the only place where corrosion took place? Via's are always something to check

Best of luck!

 

[sadmanonatrain]

volvo242gt,

Out of curiousity, when you were testing the board without the ROM SIMMs, you did have the jumper installed next to the SIMM slot, right?

When I tested the logic board without the ROM SIMMS I did have the jumper installed next to the SIMM slot. With the IIci ROM selected I don't get a chime when I turn the Mac on.

genie_mac,

there seems to be a lot of corrosion around D8 (component labelled A6, a high speed diode IIRC). I suppose it's time to get the multimeter out and start checking for continuity, shorts, opens etc.

I have been checking the continuity for all the components within the area pictured. D8 is quite corroded so I scraped some of it off so I could test continuity. My multimeter beeps so it must be OK!

Also, I have been testing continuity between ROM pins and vias on both sides of the logic board. They all check out!

I don't know how test for shorts and opens with a multimeter but I'll soon have a look.

Thanks for all the help!

 

[sadmanonatrain]

Hello all,

When I turn the IIci on I cannot turn it off via the on/off button.

So I'll replace logic board capacitors under the PSU.

I'll report back when they've been replaced!

 

[trag]

Given that you get a chime with the SE/30 and IIfx ROMs, I think you might try one of Doug's custom ROM modules. Check the Hacks forum. You'll want it programmed with IIci code, and if you just need a usable IIci ROM, then you don't need the fancy 8 MB version. The version 1 boards, if he still has some, will do the trick.

I had a similar problem with IIci ROMs. The extracts I made to repair the problem are here:

http://www.prismnet.com/~trag/Firmware/IIci/

Maybe Doug can put the code on the chips for you.

Still, it's a good idea to replace the caps under the power supply in any event. Those are what killed my first IIci back in the mid-90s. Ate through a via and it was a bear tracking down the problem.

 

[techknight]

I think he meant that he tried ROMs from machines that had chimes of death, etc.. and no chime on the IIci.

I am thinking damaged traces to the ROM address/data lines. If you look how bad that oscillator is, all the ROM traces run right underneath it. Even if it looks clean, the acid/corrosion could have been absorbed in the solder mask, or the PCB itself and causing a "leakage" current between all the traces in the bus, resulting in this system. And jumpering out the select line between DIPs/SIMM isnt going to fix that issue, as the databus is the databus.

 

[sadmanonatrain]

Hello all,

I don't think I explained the ROM SIMM situation this very well in my first post!

My IIfx works fine but when I use its ROM SIMM in the IIci it chimes normally, then it plays the chimes of death.

With the SE/30, which still suffers from 'Simasimac' after a recap and replacement Bourns filter, ROM SIMM the IIci will give the chimes of death.

I'll keep testing the traces and vias of the ROM (HH) to make sure continuity is OK. When I removed the oscillator to check underneath it the traces looked fine.

Thank you!

 

[sadmanonatrain]

Hello all,

I've just came across a document on the 68kMLA Wiki about 'Macintosh IIci RAM and ROM Pathways'.

http://68kmla.org/wiki/index.php/Macintosh_IIci_RAM_and_ROM_Pathways

It looks quite helpful for diagnosing trace problems but I don't know how to use it!

Any help would be much appreciated!

 

[sadmanonatrain]

Hello all,

I have tried repairing damaged traces and wiring ROM IC pins to their corresponding via but alas the Macintosh still will not boot with its own ROM (or any other ROM for that matter).

I've now got the HH ROM in its own socket.

I think I'll call it a day with this Logic board and try and source a new one!

Thank you for all the help,

sadmanonatrain

 

[uniserver]

you do know once you install a rom simm in there you have to set a jumper… have you tried the se/30 rom simm?

 

[sadmanonatrain]

uniserver,

you do know once you install a rom simm in there you have to set a jumper… have you tried the se/30 rom simm?

When I use the SE/30 ROM:

Without jumper-Chimes of Death

With jumper- Nothing except for a quiet pop from the speaker

Thanks

 

[Ike]

my IIci does that too with an SE/30 rom and no jumper, so that behavior is to be expected.

 

[uniserver]

Sounds to me like you need to change all the big radials.

the Iici and Iicx, even if those radials 220uf . 470uf caps don't look bad always change them anyways.

just hearing the chime of doom tells you a lot.

 

[Ike]

but is an SE/30 rom actually supposed to work in a IIcx/IIci?

 

[uniserver]

good question. i use dougg3's roms in my SI/CI/CX/SE-30 i think it works in the IIx as well? l dunno i never had a working one of those…

I have a dead II and a dead IIx, My buddy zack was going to send me a IIfx, but then this trip to Florida happened

ill try it for you right now in my CI.

- stock se/30 rom 32 bit (dirty)