Mac SE/30 parts

[Lorenz]

Hello everyone,

First time posting on this forum. I just bought a mac SE/30 who had a leaking battery. As I opened the mac, the damage was worse than expected: a few of the chips surrounding the battery were severly corroded (I2/3/4 and J2/3/4). Is there any way to salvage this board? Any way to get a hand on these chips? all other boards in the mac still look very clean.

Thanks

Lorenz

 

[BadGoldEagle]

Hey there, 

Pictures speak louder than words. If you could snap a few and post them here it'll be easier to assess the damage. 

Apparently the acid didn't run all over the board, that's good. So we'd be looking at this area of the board:



credits to James Wages (JDW) for the pictures, as always. 

If you haven't done so, remove the remains of the Maxell bomb. Then put your board in a container and fill it with white vinegar. You'll want to neutralise that acid before doing anything else. Let it sit for a bit. Come back after an hour or so and scrub out all the rust/acid on the board with a toothbrush as much as you can. Be particularly careful NOT TO DAMAGE the chip labeled RTC if it's not too damaged to begin with. 

Then, you can finish rinsing it off with hot soapy water and then just tap water. Dry it the best you can (hair dyer works wonders but IPA is also good).

Then we move on to the fun part. 

- UI2 to UI4 and UJ2 to UJ4 are just 74 series logic chips, 74LS258 to be more exact. You can get brand new ones online.

They are used for the RAM and the ROM. Speaking of the latter, you will have to remove the connector. It WILL have crap under it, shorting pins together. 

Here's the schematic for this section: https://museo.freaknet.org/gallery/apple/stuff/mac/andreas.kann/SE30_P2.GIF

- RP4 to RP6, RP8 and RP9 are resistor packs. I don't know their exact value yet... but those should be easy to find a replacement for. 

- 68882: That's your Floating Point Unit or FPU. That's a very specific part. You can probably find a replacement on ebay or something. But they can be expensive (beware of the fake clones!)

- If the acid got to the RAM SIMMs, you need to buzz them individually to check for damage. You might have to remove the connector altogether if it's too bad.

https://museo.freaknet.org/gallery/apple/stuff/mac/andreas.kann/SE30_P3.GIF

- Video ROM. As the name suggests, it's just a ROM. I think someone already dumped it. It would just be a matter of flashing the image onto a new chip and probably replacing the socket.

- PDS Connector. That's the long 120 pin connector. Acid might be shorting a few pins... If some of it got underneath it, remove it.

- Y1: Oscillator. Should be replaceable.

- RTC: NOT REPLACEABLE. IF IT'S GONE, IT'S GONE. I'm not sure the SE/30 can work without it... That's your biggest concern at the moment.

- D1 & D2: probably diodes... Not that important for now.

Ok. Now, you'll have to remove nearly all the components listed above. That can be an enormous task, I know but it's needed as some traces are definitely damaged. And since the components are above some of them, it makes the process of buzzing every single one of them easier. Try to follow each one along and test them at each end or use the schematics above.

That can be an enormous task. I know, I have done it on an SE (not SE/30). I didn't have to remove every single chip because the damage was pretty contained. You mention the 74 series logic chips as being rusted, I'm afraid you can't get away with repairing it without removing them all...

Good luck!

 

[Trash80toHP_Mini]

If you haven't done so, remove the remains of the Maxell bomb. Then put your board in a container and fill it with white vinegar. You'll want to neutralise that acid before doing anything else. Let it sit for a bit.

I've been wondering about this for a very long time. Vinegar is a fabulous cleaning agent for cap goo and using it to soften up deposits as suggested has always seemed like a good idea befor scrubbing., However it's a diluted form of acetic acid. Acid won't neutralize acid, you need a base solution for that to happen. Baking soda is what's used for cleaning acid corroded battery contacts ans such. Git of a tangential discussion to have here, but a dedicated thread on the chemistry involved would be great.

 

[Lorenz]

Hi BadGoldEagle,

First of all, thank you very much for your reply!

Here is a picture of the board after I already cleaned it. I also removed what was left of the the battery holder.

As you said, the 74 chips are damaged. Also, the resistor packs RP8 and RP9 on my picture are also damaged (they are on a different location than on your board). They are labelled SOMC1601 201G and 102G, I wasn't able to find these specific ones or their specifications online yet. SOMC1601 103G and 203G seem to be more easily available, could that be an alternative?

The RTC chip seems in good condition besides a few traces of corrosion.

Again thank you very much for your help.

Regards,

Lorenz

 

[dochilli]

There are some components missing (Y1, D1, C12). The 68882 looks damaged, also the UJ4 (F258). I think it will be difficult to repair this board. May be possible, but not easy.

Good luck!

 

[Lorenz]

Hi,

Update of tonight: I ordered all the parts surrounding the battery that looked damaged (74 chips, 68882, oscillator, diodes, and capacitor that was completely gone and even a new battery holder).

The only thing missing are the resistor pack: not quite sure how to get these.

Thanks again!

Regards,

Lorenz

 

[Bolle]

You will have to fix a lot of broken traces besides replacing those components.

There is visible damage to some of them and as soon as there is visible damage there will be more hiding from what you can see.

The SE/30 will start without the RTC/PRAM but you won’t be able to boot from SCSI without it.

A RTC chip from the SE or any other Mac II that uses the same form factor will work as a replacement.

 

[krishnadraws]

I am in the same boat as Lorenz. I’ve attached a photo of the Mac SE/30 I am working on.

first question: Is this even feasible to work on? I’ve restored a Mac SE which was only in need of recapping (analog board, PSU, and logic board) but this Mac SE/30 that arrived from eBay had an exploded Maxell battery

second question: 

is it possible to share a parts list on where you picked up the 258s and diodes, Lorenz?

as far as I can see the RTC seems to be ok, after some cleaning. 
 

I have placed the logic board in an IPA bath (day 1) and a distilled vinegar bath (day 2), using a toothbrush to scrub corrosion as best as I can.

thanks!

 

[Bolle]

I see a lot of broken traces, that’s going to be some serious work to get it back into working order.

It can be done though, I fixed a battery victim that needed 25 traces/vias to be fixed.

 

[krishnadraws]

I'm up for the challenge - I've been watching a few videos by Bruce (Branchus Creations) and I'm willing to give repairing the traces a try. If worse comes to worse, and I fail at it, I have something to practice on. I'm on the lookout for replacement wires to fix the traces so any specific sizes / brands would be greatly appreciated. 
 

On another note, the case on this Mac is worse for wear (the guy who shipped it barely added any packing so there are two major cracks on the front bezel.  (I'm on the hunt for a new front bezel, too.)

 

[CC_333]

I have one, but it's from an SE.  Hope that's OK?

PM me if interested.

c

 

[krishnadraws]

Thanks, CC_333! I'm not in any rush at the moment but I will definitely reach out when I've gotten further along with the Mac.