This was an email from Marty S., who wrote, "Just wanted to let you know that there are bad caps on Apple G4 eMac logic boards. There were 5 different models, and I think there were only slight differences between the logic boards. The one in the photo is Apple part # 820-1591-A, from a 1.25 GHz system. Needs 5 units of 1000 uF 16v, and 8 units of 1800 uF 6.3v. One happy aspect that these are pre-RoHS machines, which means you can actually get the failed caps out without a struggle."
Thank you Marty for the information, and the insight about the standard solder. I have the high quality, low ESR cap kits available for sale at www.jwestsales.com.
Exactly how how do you test the PSUs out on the Apple iMacs?
How do you turn on the iMac G5 power supply when it is out of the computer?
iMac G5 Power Supply Connector – P-1
1. +3.3 – BlackA3B
12. +3.3 – BlackA3B
2. +3.3 – BlackA3B
13. +12v – BrownA3B
3. GND – BlackB4B
14. GND – BlackC4B
4. +5v Gray/PurpleA4B
15. On/Off – Gray
5. GND – BlackB4B
16. GND – BlackC4B
6. +5v Gray/PurpleA4B
17. GND – BlackC4B
7. GND – BlackB4B
18. GND – BlackC4B
8. PG – Blue
19. +12v – BrownA3B
9. +5.1Vsb – Purple
20. +5v Gray/PurpleA4B
10. +12v – BrownA3B
21. +5v Gray/PurpleA4B
22. +20v to +24v – Brown
On the 661-3350 power supply and other similar PSUs, jumper pins 15 (gray) and 16 (blk/gnd) to turn the PSU on. With the power supply on, you should be able to read all the voltages listed above with a DC voltage meter. Between pins 22 and any GND pin, you will see approx. 24vdc, which is needed for the backlight. Note that the plug is numbered on the wired side of the connector plug. You will need some good lighting to see the numbers. A small flashlight comes in handy.
When reading the voltages, it is always a good idea to check both for proper DC voltage and AC ripple voltage. Note that AC ripple voltage should be relatively low, in the low millivolts range.
From what I have been able to tell, the other power supplies in both the 17 inch and 20 inch iMac G5 computers all used the same DC voltage pinout arrangements. I believe the voltage pinout arrangements are different on the Intel iMacs and some of the iSight models.
If anyone has more information for any of the power supplies (especially the pinout arrangement) used on the various Mac products, including the various PPC models, Intel Models, and Power Macs, please send it to me.
Voltage pinouts listed above cover the following Apple PSUs: 661-3350, 661-3289, 614-0353, 614-0296, 614-0297, 661-3351 614-0923 614-0352 614-0294, AP14P46, 614-0398, 614-0326, 661-3625, 661-3289, AP13PC97, 614-0279, DPS-180SB, A 614-0334, 614-0366, 614-0326, 614-0398, 614-0353, 614-0328, 661-3627, 614-0327, 614-0325, 614-0365, 614-0329, 661-3290, Manufacturer Part Numbers: DPS-180QB-1A Rev 01, API4PC47, DPS-180QB ) along with a number of different manufacturers including: (ACBel API3PC96 – Celetronix Q45B – NPFC), and additional manufacturers’ part numbers than what is listed here.
PG acronym represents the Power Good signal. I found the following reference in the Wikipedia when it comes to talking about power supplies in general for PCs.
In addition to the voltages and currents that a computer needs to operate, power supplies also provide a signal called the Power-Good signal, sometimes written as Power_OK or Power_Good or you can distinguish it by its gray color. Its purpose is to tell the computer all is well with the power supply and that the computer can continue to operate normally. If the Power-Good signal is not present at startup, the CPU is held in reset state. If a Power-Good signal goes down during operation the CPU will shutdown. The Power-Good signal prevents the computer from attempting to operate on improper voltages and damaging itself.
The ATX specification defines the Power-Good signal as a +5 volt (V) signal generated in the power supply when it has passed its internal self-tests and the outputs have stabilized. This normally takes between 0.1 and 0.5 seconds after the power supply is switched on. The signal is then sent to the motherboard, where it is received by the processor timer chip that controls the reset line to the processor.