Alright, repair is done!
I guess the flyback was still working. However, it wouldn't make any sense that if the flyback would be broken there wouldn't be any sign of life. Not even the power button led pulsing...
This block diagram can be found in the manual. The motheboard is getting its power through the Video neck board, the flyback doesn't seem involved.
Anyhow, here's more on the repair.
This is a list of the caps in the machine (and the ESR and capitance values I measured)
Some caps, like the C710 seem to have strange readings. The big cap 905 was bulging. I decide to replace all of them, preventing the need to take the machine apart a second time.
I replaced all of the caps with 105°C ratings and low ESR if possible. I replaced some caps with higher values (because my local supplier didn't had them in stock)
Besides that I also replaced two resistors who looked burned and had lower readings than they should.
This is what the board looked like afterwards, loaded with nice and shiny new caps!
Before assembling the whole thing again, i decided to check voltage readings from the video neck board. Here are the results.
I didn't replace the caps on the Down Converter board because those caps still looked brand new. After connecting everything and cleaning all the dust trying it resulted in the happy mac sound and a smooth boot. I'm happy this one is saved!
I guess the flyback was still working. However, it wouldn't make any sense that if the flyback would be broken there wouldn't be any sign of life. Not even the power button led pulsing...
This block diagram can be found in the manual. The motheboard is getting its power through the Video neck board, the flyback doesn't seem involved.
Anyhow, here's more on the repair.
This is a list of the caps in the machine (and the ESR and capitance values I measured)
Code:
C936: 6,3V 330uF Samyoung KMG (105°C) 6x11 | measured: 303,7uF 1,40 Ohm
C939: 10V 1000uF Samyoung KMG (105°C) 10x12 | measured: 977,0uF 0,50 Ohm
C940: 10V 1000uF Samyoung KMG (105°C) 10x12 | measured: 926,8uF 0,50 Ohm
C722: 16V 47uF Samyoung SMS (85°C) 5x10 | measured: 41,8uF 1,42 Ohm
C947: 16V 47uF Samyoung SMS (85°C) 5x10 | measured: 38,5uF 1,26 Ohm
C713: 16V 100uF Samyoung SMS (85°C) 6x10 | measured: 91,3uF 0,82 Ohm
C948: 16V 100uF Samyoung SMS (85°C) 6x10 | measured: 94,8uF 0,62 Ohm
C938: 16V 470uF SAMWHA (105°C) 8x11 | measured: 454,5uF 0,20 Ohm
C951: 16V 470uF SAMWHA (105°C) 8x11 | measured: 430,2uF 0,20 Ohm
C602: 16V 1000uF Samyoung SHL (85°C) 10x16 | measured: 890,6uF 0,10 Ohm
C604: 16V 1000uF Samyoung SHL (85°C) 10x16 | measured: 939,2uF 0,10 Ohm
C941: 16V 1000uF Samyoung KMG (105°C) 10x16 | measured: 993,3uF 0,23 Ohm
C922: 25V 33uF Samyoung SMS (85°C) 5x10 | measured: 26,9uF 1,94 Ohm
C937: 25V 33uF Samyoung SMS (85°C) 5x10 | measured: 24,3uF 1,76 Ohm
C906: 25V 47uF Samyoung KMG (105°C) 5x10 | measured: 10,9uF 3,40 Ohm
C934: 25V 1000uF Samyoung KMG (105°C) 10x20 | measured: 948,4uF 0,17 Ohm
C935: 25V 1000uF Samyoung KMG (105°C) 10x20 | measured: 948,4uF 0,32 Ohm
C710: 50V 1uF Samyoung SMS (85°C) 5x10 | measured: 0,9uF 10,70 Ohm
C916: 50V 1uF Samyoung SMS (85°C) 5x10 | measured: 0,9uF 2,60 Ohm
C945: 50V 1uF Samyoung SMS (85°C) 5x10 | measured: 0,8uF 2,60 Ohm
C520: 50V 10uF Samyoung SMS (85°C) 5x10 | measured: 9,1uF 1,08 Ohm
C981: 50V 10uF Samyoung SMS (85°C) 5x10 | measured: 9,2uF 1,23 Ohm
C946: 50V 4,7uF SAMWHA (85°C) 5x10 | measured: 4,3uF 1,03 Ohm
C918: 63V 47uF Samyoung KMG (105°C) 6x12 | measured: 44,7uF 2,60 Ohm
C603: 63V 220uF Samyoung SMS (85°C) 10x20 | measured: 203,8uF 0,10 Ohm
C724: 100V 10uF Samyoung SMS (85°C) 6x10 | measured: 10,1uF 0,58 Ohm
C719: 100V 22uF SAMWHA (85°C) 12x25 | measured: 21,7uF 0,12 Ohm
C949: 100V 100uF Samyoung KMG (105°C) 10x20 | measured: 94,8uF 0,20 Ohm
C950: 100V 100uF Samyoung KMG (105°C) 10x20 | measured: 96,9uF 0,22 Ohm
C933: 200V 22uF Samyoung KMG (105°C) 10x15 | measured: 21,0uF 2,20 Ohm
C723: 200V 33uF Samyoung SHL (85°C) 10x20 | measured: 32,1uF 1,44 Ohm
C726: 200V 33uF Samyoung SHL (85°C) 10x20 | measured: 30,9uF 1,33 Ohm
C932: 200V 47uF Samyoung KMG (105°C) 12x20 | measured: 46,1uF 1,06 Ohm
C905: 400WV 470uF Chemi-Con (105°C) 30x60 | measured: 434,1uF 0,08 OhmI replaced all of the caps with 105°C ratings and low ESR if possible. I replaced some caps with higher values (because my local supplier didn't had them in stock)
Code:
C722 & C947: 16V 47uF replaced with 16V 100uF
C922 & C937: 25V 33uF replaced with 25V 47uF
C933: 200V 22uF replaced with 200V 27uF
C723 & C726: 200V 33uF replaced with 200V 47uF
Code:
R957: should be 5,6kOhm but reading was only 3,3kOhm
R971: should be 100kOhm but reading was only 80kOhmBefore assembling the whole thing again, i decided to check voltage readings from the video neck board. Here are the results.
I didn't replace the caps on the Down Converter board because those caps still looked brand new. After connecting everything and cleaning all the dust trying it resulted in the happy mac sound and a smooth boot. I'm happy this one is saved!