Re: Imac G5 Video/Display problems.
Suspect that your problem's due to a failed ball array that connects the GPU to the logic-board. For some reason this video failure symptom is more prevalent in the 17" G5 series than the 20". But when you replace all caps on a G5 board & there's still no video...it's likely that the GPU's separated/separating from the board. Strange that you get positive diagnostic light indicators, or that ASD did not detect a failure point, but the fact that you can attach a secondary display successfully underscores that the on-board video chip's...
dbridgma
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Last Activity: 01-20-2010, 07:31 AM
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Re: iMac G5 1.8G - Fresh caps, but not quite there...
Didn't miss your instructions, Toast...just didn't process them fully while swimming in a sea of conflicting multi-meter advise, much of it generic...& since the Blue ESR meter came assembled...page 9 of "assembly" didn't leap out.
This is all news to me, so each phase is fraught with missteps, half-recollected instructions. I'm slow...but trainable:-)
DanielLeave a comment:
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Re: iMac G5 1.8G - Fresh caps, but not quite there...
Keri,
Thanks for the detailed summary of how to work with the AnaTek Blue ESR meter. It was not obvious how to zero it out before taking readings...or that doing so was necessary. Glad you chimed in.
So I used your method to reset/restart the meter before each testing...when I do this the caps either test at .01 (not the .09/.08 that the meter registers without reset) or .00. So, I'm assuming this means that they're within the range of functionality...although a cold joint may be lurking somewhere....Leave a comment:
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Re: iMac G5 1.8G - Fresh caps, but not quite there...
Okay, I'll test again if you suspect that these ESR readings are wacked. The Blue ESR meter is consistently measuring .08 or .07, which I interpreted to be below the .1 max for caps above 500uF (as summarized on the Anatek chart). But you're saying the caps in circuit should be .00 or .01? Their chart shows .01 as the base of the chart, all readings are above it...
Will bad solder joints push the in circuit ESR numbers upward?
DanielLeave a comment:
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Re: iMac G5 1.8G - Fresh caps, but not quite there...
Correction to the ESR readings on the caps that were replaced on 06-01-o9...Anatek Blue readings were uniformly .08 or .09, not .8 or .9 as I erroneously recorded in that earlier post.
Those readings check against Anatek's website, as good cap ESR values on 1800uF v6.3 caps.
I'm checking these boards for continuity, however, I'm doubtful that I know what I'm looking for. Somewhere continuity has been broken because now I can only get a single trickle (green) diagnostic light. The second (PSU) light...Leave a comment:
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Re: iMac G5 1.8G - Fresh caps, but not quite there...
Musing over what could be causing the iMac 1.8GHz LCD failure...I'm pondering whether the temporary presence of extra caps (see post on 06-01-2009 above), and perhaps, solder that entered the thru-holes might have produced/contributed to the condition that's stopping the logic board from posting, or booting.
I inadvertently added two extra caps to these Rev A boards (the Rev B actually populates the extra holes with additional caps) & am now wondering if residual solder in the holes might be affecting the board's...Leave a comment:
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Re: iMac G5 1.8G - Fresh caps, but not quite there...
So, as a last resort tested all capacitors I replaced with an Anatek ESR unit that I got recently...and all replacement capacitors check out. They all come up with a .8 or .9 ESR reading on my Blue ESR meter. All solder-joins seem sound...or at least they check out when probed. So the good news is: I didn't destroy any caps when soldering them.
But I've still got no (3rd) LED diagnostic light, & cannot boot either G5. The single successful boot is looking like it was a fluke.
I suppose I probably...Leave a comment:
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Re: iMac G5 1.8G - Fresh caps, but not quite there...
Yes, many interesting differences among the various early iMac PSUs. I looked, but didn't dismantle that odd menagerie of caps incrusted in glue.
So, to recount, I discovered that I'd mis-soldered extra 1800uF 6.3v caps onto the midplane in the group near the heat sink. There's supposed to be a cluster of 14 (with a unused row of 2), and I stuck 2 extras in there. From left to righ It goes: row 1: 4 1800uF 6.3v row 2: blank (row of 2) row 3: 4 1800uF 6.3v row 4: 6 1800uF 6.3v
Well, I initially booted...Leave a comment:
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Re: iMac G5 1.8G - Fresh caps, but not quite there...
I'll go over the boards again according to your instructions. I suspect that you're correct...there's a bad connection lurking somewhere. But finding it is the challenge.
By the way, I did the 20 1800uF & 5 1000uF caps. But notice that there are two Nichicons in the (lower right) corner of the board that I didn't replace--for some reason Warholic's kit did not include those two. Not sure why he calls these 25 a "full set" for the first generation iMacs.
I have 3 unmodified PSU's pulls...Leave a comment:
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Re: iMac G5 1.8G - Fresh caps, but not quite there...
Been over these boards about 50 times looking for loose connections/connectors. Can't find anything suspicious. Went back over solder joins because two were not as solid as I'd like. I'm stumped by the failure of the board to activate the 3rd green light (the LCD-related indicator) which signals that the system's likely to boot normally.
The very first time (the 1st) re-capped board was powered, everything went smooth...all 3 lights illuminated & I had video, fans, the whole enchilada. I was ecstatic, however,...Leave a comment:
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Re: iMac G5 1.8G - Fresh caps, but not quite there...
I'm up against the same predicament. I have two iMac G5 17" 1.8Ghz units that I recapped (with new PSUs & inverters).
The logic boards sometimes gets all three diagnostic lights lit...but there's no video. The screen remains black. I disassembled & then reassembled both & was able to get one to boot fully (fans running a normal speed, hard drive spinning up) minus any video. But now neither one will light the third LCD green light or fire the hard drive/fans.
Does anyone know how...Leave a comment:
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