Hello and happy New Year!.
Today I received an Imac G5 20" 2.0Ghz producing no video except a dark purple tinge.It would display on an external monitor and I managed to run ASD which showed no errors in video or any other component,all 3 diag leds were on.No overheat led was displayed.I changed the inverter and screen with same make model.No video.
Time to look very carefully at the caps.Three to the right of the CPU housing looked slightly odd,not in your face bad,but I pulled them anyway.Using my Atlas ESR meter with probe compensation,1 measured 8ohms,another 6,the last 5.Recapped with Nichicon HZ's rated at 1800 @ 6.3v.Reassembled to see the results,no video.
Time to pull the lot.The Ruby 1000 @ 16v x5 were all spot on.So far,twenty of the Chemicon KZJ 1800 @ 6.3v have all measured between 2200-2400 on the cap scale at 0.00 Ohms.
I know these are above rated but they still fall in the 20% margin,just!.I've only had a video signal problem once before so my experience is limited on this one,the cause of the other one was a faulty LVDS cable,but as I've said above,I ruled out any other possibility.
In any bodies experience,would a bad cap(s) be the cause of this problem or could any one with a similar experience point me in the direction of a possibe failure in another component.I had a look at the video connector on the board with a magnifying glass,the solder joints look fine,but if there is a test I could perform with a DMM,please let me know,
I really would appreciate the help!.
Today I received an Imac G5 20" 2.0Ghz producing no video except a dark purple tinge.It would display on an external monitor and I managed to run ASD which showed no errors in video or any other component,all 3 diag leds were on.No overheat led was displayed.I changed the inverter and screen with same make model.No video.
Time to look very carefully at the caps.Three to the right of the CPU housing looked slightly odd,not in your face bad,but I pulled them anyway.Using my Atlas ESR meter with probe compensation,1 measured 8ohms,another 6,the last 5.Recapped with Nichicon HZ's rated at 1800 @ 6.3v.Reassembled to see the results,no video.
Time to pull the lot.The Ruby 1000 @ 16v x5 were all spot on.So far,twenty of the Chemicon KZJ 1800 @ 6.3v have all measured between 2200-2400 on the cap scale at 0.00 Ohms.
I know these are above rated but they still fall in the 20% margin,just!.I've only had a video signal problem once before so my experience is limited on this one,the cause of the other one was a faulty LVDS cable,but as I've said above,I ruled out any other possibility.
In any bodies experience,would a bad cap(s) be the cause of this problem or could any one with a similar experience point me in the direction of a possibe failure in another component.I had a look at the video connector on the board with a magnifying glass,the solder joints look fine,but if there is a test I could perform with a DMM,please let me know,
I really would appreciate the help!.
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