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#1 2014-05-30 04:26:45

uniserver
Member
From: Sf, Mi
Registered: 2014-05-15
Posts: 955
Website

Mac IIx / Mac II Will not power on after a re-cap?

Please make sure to re-cap your Mac II or IIx first.

Then Please try this first:

(To verify your PSU and and main board work).

If those are verified and your machine still does not power on with the Power Switch or Keyboard...

then try this:

-- From the help of guys like bbraun, and others.

Here is a quick fix that you can try.  That should get your machine powered up again.

Meter out R3 to R18 (for the Mac II) (on the bottom of the main board)
Meter out R3 to R19 (for the Mac IIx)

If its open, run a wire connecting them. Then it should power on,  It's kind of a common problem.

Last edited by uniserver (2014-05-30 05:11:14)


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#2 2014-05-30 05:44:36

mcdermd
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From: Corvallis, OR
Registered: 2014-05-12
Posts: 940
Website

Re: Mac IIx / Mac II Will not power on after a re-cap?

I had a IIx that was in pretty bad shape. Even after a recap and fresh batteries, it would not power on or even jump start. It ended up it had three bad traces, eaten away by cap goo. This goes for all boards that have leaked extensively: check the traces. If any look blackened or even dark, put the meter on them to test continuity. When you find a bad one, use a piece of wrap wire to jump between the closest points. I like to hit the wires with a dab of hot glue at stress points to mimic the repair style Apple used at the factory. It takes time but in the end you can usually get it fixed.


Daily Drivers: 27" iMac 2.8 GHz Quad-Core i7 (Late 2009), 21.5" iMac 2.7GHz Quad-Core i5 (Late 2013), 11" Macbook Air 1.6 GHz i5 (Mid-2011)
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#3 2014-05-30 15:10:42

bbraun
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Registered: 2014-05-29
Posts: 1,064
Website

Re: Mac IIx / Mac II Will not power on after a re-cap?

If none of the above works, there's also two 74HC132 NAND chips on the II/IIx/IIci and possibly others, that are involved in the power on process that can go bad.  Typically those chips are pretty simple and shouldn't fail, but either corrosion due to the capacitors leaking, or some bad voltages (possibly also caused by capacitors leaking) can cause them to fail.

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#4 2014-05-30 15:57:07

mcdermd
Member
From: Corvallis, OR
Registered: 2014-05-12
Posts: 940
Website

Re: Mac IIx / Mac II Will not power on after a re-cap?

landonf @ mac68k.info wrote:

The machine now boots 100% reliably after replacing the SN74HC132 at UE13. Here's the new one:

This has to be a leaked electrolyte issue. My IIci had a bad trace right at pin 2 on UE13. I bridged the bad spot and it was good to go.


Daily Drivers: 27" iMac 2.8 GHz Quad-Core i7 (Late 2009), 21.5" iMac 2.7GHz Quad-Core i5 (Late 2013), 11" Macbook Air 1.6 GHz i5 (Mid-2011)
See the restored heroes here.

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#5 2014-05-30 21:30:24

uniserver
Member
From: Sf, Mi
Registered: 2014-05-15
Posts: 955
Website

Re: Mac IIx / Mac II Will not power on after a re-cap?

Great info guys!


#I Re-Cap √Mac √NeTX √Amiga Boards - A/B - PSU# (MacCaps.com)  Modern SCSI HD's - For Old Macs - Pre Cfg'd - 10k RPM! 73gb!! $50 + free shipping  -- Mac 128K Re-Ram kits (16 Chips) $35 + shipping, Floppy Issues?-> Bourns Filter Solution 128k - SE/30, $16 + shipping

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#6 2014-05-31 01:16:47

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac IIx / Mac II Will not power on after a re-cap?

Awesome! Wonder what other shotgun fixes there might be.

Last edited by techknight (2014-05-31 01:18:16)

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