Resolved New Faulty Macintosh Classic II! Help please? :)

[tevion5]

I just received my (known to be faulty) Macintosh Classic II that I acquired for the cost of shipping thanks to a very generous woman on the forum.

Unfortunately, the rabid gorillas at DPD couriers managed to damage the Mac's case during delivery Just like they did with two of my Power Mac G5's...

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Anyway, I plugged it in and at first I was largely disappointed as I could hear the HDD spinning away, yet there was no startup "beep" and nothing came up on screen at all.

However, I then thought that it's probably just the brightness! The same thing scared me when I got my 512Ke, and the brightness just turned out to be at 0. (Who does that just to terrify the buyer? ). Anyway, the CRT is clearly fine as I can get some image to come up on screen. However, it is obviously is far from fully functional. (Accidental alliteration, apologies.)

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I believe this is a very common issue with these Classic II's and I've read of many people who have been able to fix them with little difficulty.

Any advise guys?

 

[tevion5]

I found this video:

http://youtu.be/EwxXHTwEIc0

I think I'll give this a try. It'd be a nice easy quick fix if it is the problem!

 

[DZ/015]

You could try cleaning/reconnecting the ram simms and other internal connections first. This may get it working. It will also give you an opportunity to inspect the logic board for leaky caps. I would plan on replacing them even if they are not leaking.

Also, just want to post a link to the se/30 repair page that I believe initially told of these type of problems. There is still good info here even after all of these years.

 

[AmestrisXServe]

My first suspicion is that a socketed DIPP has lifted from the socket, likely due to the impact. Try seating every socketed IC, before doing anything further. Be very careful around the yoke on the CRT.

I expect you know how to crack open a classic casing. (They are ever so much of a joy to force back together.)

The service source manual for the Classic II isn't much of a help. It states:

Check/Replace Power/Sweep PCB
Replace Mainboard

Clearly, that isn't the extent of diagnosing this problem.

I'll see what I can find in my old blue & white binders for the Classic II, as that series was far more comprehensive than Service Source.

 

[MacTech68]

As the guy says in the video, it is NOT a permanent fix. Those capacitors leak, lose their value, and the stuff they leak is corrosive.

So, depending on how long they've been leaking, cleaning may initially help, but there may be tracks that are already corroding, and some tracks that have been etched all the way thru, breaking the connection.

In my experience, it's never such a "simple" fix.

 

[AmestrisXServe]

Always replace a bad cap. Period, end of story.

I looked at the old TS books, and the flowchart is identical. Without Mactest CL, and a loopback connection, you will need to perform physical inspections of all the components, reseat the SIMMs, and fully seat any DIPPs, and then check the system.

I would not suspect a capacitor in this case, purely based on personal experience with these systems.

 

[tevion5]

I expect you know how to crack open a classic casing. (They are ever so much of a joy to force back together.)

In terms if opening the case, I need to buy a screw driver long enough to get at the two top screws. I assumed there was no further difficulty after the screws have been removed?

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As the guy says in the video, it is NOT a permanent fix. Those capacitors leak, lose their value, and the stuff they leak is corrosive.

So, depending on how long they've been leaking, cleaning may initially help, but there may be tracks that are already corroding, and some tracks that have been etched all the way thru, breaking the connection.

In my experience, it's never such a "simple" fix.

So if I reseat all every IC on the motherboard and try that.

Then, do the cleaning trick and if that works, replace the capacitors right? Would replacing them be a permanent (5-10 year) fix?

How difficult is replacing the capacitors?

 

[MacTech68]

So if I reseat all every IC on the motherboard and try that.

Then, do the cleaning trick and if that works, replace the capacitors right? Would replacing them be a permanent (5-10 year) fix?

How difficult is replacing the capacitors?

If it were me, I'd be replacing the capacitors, (they will fail if they haven't already) and during that process, cleaning the board and checking for etched tracks.

However, your procedure makes perfect sense if you like wetting the board with plain water. The thing that worries me about dish-washer tricks and washing with water is drying the board quickly and COMPLETELY - especially things like the rear connectors which can retain water quite well and moisture being retained underneath components (out of sight). Cleaning agents that evaporate are much less of an issue but cost pennies.

Is it possible to do? Sure! Most PCBs are washed at some stage of manufacture, but these are under controlled conditions with covers for certain components.

The other thing is that before you clean the leaked electrolyte away, you can see if it has flowed under components. Once you clean it, you have no idea how far it has traveled.

Replacing the capacitors is not what I'd call easy. There are risks involved and you need to research capacitor sizes to find which ones fit the solder pads. (I recommend using solid surface mount tantalum capacitors).

 

[AmestrisXServe]

In terms if opening the case, I need to buy a screw driver long enough to get at the two top screws. I assumed there was no further difficulty after the screws have been removed?

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So if I reseat all every IC on the motherboard and try that.

Then, do the cleaning trick and if that works, replace the capacitors right? Would replacing them be a permanent (5-10 year) fix?

How difficult is replacing the capacitors?

I used to have quite a few Mac Cracker driver: They are very long (16") Torx drivers. You do not want anything that takes bits: You want a dedicated screwdriver, and these used to be a few dedicated drivers especially for original Macs. The trick was to unscrew the fasteners almost all the way, and use a small mallet to whack the end of the driver to separate the case, which also requires precise pressure to reseal.

You won't see any on the market advertised as such now, but this is essentially what you need.

The original Mac, through the SE was always a bloody pain. As I recall when Apple designed the case, they had a deal of trouble on the production line, as they couldn't close the systems, until an engineer came down with a wooden vice of some kind, and started crunching them down by hand.

The original Mac, through to the Plus, also have a screw behind the battery cover, that no-one wants to miss. (I seem to recall this was changed on the SE and later.)

You should use DeOxit for cleaning.

 

[MacTech68]

There was a MacOpener tool that dealers could purchase that fitted between the front bezel and the rear case, and with a scissor action, spread the two halves apart. See below. I never used one.

I found that holding the side of the machine against my chest, and grasping the rear with one hand and the front vertical edge in the other, that I can prize them apart quite easily. Just why this works, I'm not sure.

I've certainly come across some tight cases and the "whack the loosened screw" trick does work with those.

 

[AmestrisXServe]

I found those to be rather clumsy, and hard on the hands. The long Torx driver, with a small mallet, worked for me for ages.

 

[tevion5]

Fixed it! (...for now...sort of...)

I have some good news!

I opened up the case after getting a long as i could find torn screw driver in a local tool shop. It just about reached the screws down in those little tunnels.

After the lid was off I was naturally jumpy about the high voltages in the CRT, as I have studied CRT's in Physics and know how they work and have read about voltages of around 2000V!

However, I fashioned a tool to earth the charge by taping an anti static wrist band to a screw driver like a pro. I prodded the screw driver behind the suction cup and made contact with the anode, making my job slightly less deadly.

Next, I set about carefully detaching the 3 cables connected to the motherboard, making sure not to destroy the glass tube in the CRT in the process. After not much difficulty, I got the motherboard out and quickly confirmed my suspicion of leaky caps. Textbook. Like somebody spilled their cola all over the damn thing.

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Now, I used an old toothbrush and started trying to scrub it with warm water. (After removing the RAM). However this proved very tough. Then from chemistry, (high school science proving applicable in the real world for the second time folks! ) I remembered an alkaline might neutralise the acid and produce nice evaporating water to replace that sticky acid. I made a solution of toothpaste and warm water and after a little (careful) scrubbing, the acid seems to be gone in no time.

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Then, I left the whole motherboard dry in my warm room for a few hours with a desk fan giving it some attention. When I went to bed, I turned the fan off and waited until the following evening before looking at it again.

The next evening, I checked to make sure there were no droplets of water hanging about, and when I was certain, I put it all back together and prayed to Steve. (I was so excited to test it I even forgot to put the RAM back in, leaving it with only 2MB instead of 4 )

I plugged it in, turned on the Mac, and.....zebra lines. Again.

Then....I tried turning it off and on a few more times before...

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Success! (somewhat)

Pretty happy with myself considering this is the first time I've "repaired" a part, instead of just replacing one, like with nearly every computer related hardware issue. These big parts old machines are fun to work with. My Apple II Plus is like a lego machine. I've also dissasembled a Power Mac G5 which was probably the most horrendous 3 hours of my life.

I'll probably try giving it another scrub as I think I missed a few spots. Replacing the caps seems a little beyond my expertise after I've read up on the topic.

I was thinking if there was anybody (preferably in the UK or Europe as I'm in Ireland) that could replace them for me if I sent them the Motherboard?
(For money of course)

Lemme know what you guys think of my work anyway, thanks for reading!

 

[MacTech68]

Well done!

I would say, that the caps probably need a little warmth to work, which is why it didn't initially work. This is common for these caps and is the first sign of failure. Eventually, they'll stop working.

The good news seems to be that no tracks have been etched thru, as yet.

I perhaps live too far away to assist with re-capping.

Hopefully somebody else can!

 

[AmestrisXServe]

My eyes have become too bad to do SMD operations on any regular basis, else i would assist you. Really, it isn't that difficult, and you could practice on a toss-away ATX, or PCI board.

 

[bigeasy_uk]

Congrats Tevion! I'm glad you got yours working. Mine sadly wasn't so lucky, but it is halfway to being a pretty cool basilisk machine Just waiting on a small psu and a speaker to finish it off.