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M1296 12" Macintosh RGB monitor warning


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Hi everyone

A recent project has been servicing my Apple 12" Macintosh RGB monitor M1296 made by Mitsubishi.  I have two of them in mint condition, both known to have minimal use.  I turn them on every 3 months or so and keep a diary simply 'Working great! 01/01/2018".  Well I went to test one and found vertical fold over symptom and quickly turned it off.

 

Top down inspection looked fine so I started to dismantle the main and neck boards.  This requires desoldering ground cables, the design is not user friendly at all.  

 

The further I got to the bare boards the more shocked I became.  My hands were becoming stained with a fake tan look and I could smell the oil.  When the main board sits in the plastic cage, was a thick line of wet capacitor goo.  The whole main board was sitting in a pool of electrolytic leakage.  I had to wear gloves to desolder and wipe down my ESD mat which was stained from all the crap.

 

My theory is the sheer level of 'wetness' to both boards caused it to fry itself.  All quite confusing as you'd think being 'low miles' that they'd last longer.

 

I would never turn a M1296 on again until I've washed the boards.  BOTH monitors were equally as 'wet', just the one shown had worse corrosion.

2018-03-17_17-21-29.thumb.jpg.c26eeb45a47696d1569a7f801031d9ee.jpgI spent at least an hour going over both sides with thick and thin cotton tips and alcohol to mop up the goo.  Later in the project I put the main board in a sink and poured alcohol over the solder side.  Again to my surprise , the alcohol turned brown and the sink was full of brown run off.  So the board was that filthy that even manual cleaning wasn't enough - it needed a scrub and rinse.

 

Element14 are stuffing me around with delivering my replacement caps so I am yet to actually re-cap it.

 

For the first time online I can present a reference list of capacitors:

 

image.png.a3da88c5778a3aab0ae20b766ba37e9b.png

Main board V uF Ordered
C525 50 0.1 1
C401, C413, C502, C523 50 1 4
C507, C520 50 10 3
C915, C921 100 10 2
Unknown 160 10 1
C416 25 22 ?
C105, C526 50 47 2
West of C417 160 82 1
C517 25 100 Yes
C414, C5151 50 100 2
C519 25 220 1
C205 100 e 1
C908 450 220 1
C919 180 330 1
C148 6.3 2200 1
C920, C417 35 2200 2
       
Neck board V uF Qty
C6B5, C6R5, C6G5, C207 160 1 4
C203 50 1 1
C2B4, C2G4, C2R4 50 2.2 3
C6B3 25 47  
C6R3 25 47  
C6G3 25 47  
C2R2,C2R1,C2G1,C2B1,C2G2,C2B2 25 47 9
C206, (C517 from main board) 25 100 2

 

2018-03-13_00-28-32.thumb.jpg.439a40205d59d3e0954d8aa38e014d0b.jpg

 

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This has been discovered by me a few years ago, I did a youtube video on it, but I never uploaded the 2nd part due to some issues with the footage. 

 

but yes the capacitor is a known leaker, its caused by the 2 resistors boiling right next to it causing this problem. 

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