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

uniserver
Member
From: Sf, Mi
Registered: 2014-05-15
Posts: 956
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)


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

mcdermd
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From: Corvallis, OR
Registered: 2014-05-12
Posts: 1,022
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
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From: Corvallis, OR
Registered: 2014-05-12
Posts: 1,022
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: 956
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: 453

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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#7 2020-01-31 01:39:31

ziggy90127
Member
Registered: 2020-01-31
Posts: 1

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

I aquired 2 Mac IIci's.  One did not boot at all.  I re-capped the motherboard, and it boots.  The other was booting, then got temperamental, then stopped booting.  I re-capped it, no improvement.  I removed UE13 and found this:

IMG-0694a.jpg

Electrolyte from the capacitors got between pin 7 and the circuit board.  I scraped the junk off pad 7 to get this:

IMG-0712a.jpg

I soldered on a new 74HC132:

IMG-0717a.jpg

But it still didn't boot.  I had another 74HC132 for UD13, but I decided to try to just run a bead flux and then solder over the pins of UD13 and UB13, and viola! It boots!!  A bit messy:

IMG-0718a.jpg

A note about re-capping:  The axial through hole capacitor by the slots requires a lot of heat to remove.  To get lingering solder out of the holes I used the method of heating one side and pushing a pencil pen lead through the hole.

Last edited by ziggy90127 (2020-01-31 01:42:36)

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