hi , you will have to do some reading here but this guide may help . internal battery change and reset may help.
do you get chime while powering on ?
do you get apple logo ?
Resetting the pram , after battery replacement can help .
Please follow the full guide for your Mac :-http://support.apple.com/kb/HT1379?viewlocale=en_USextra info :-Contents of PRAMSome Macintosh computers may not have all the settings described below.Settings Stored in PRAM :-Status of AppleTalkSerial Port Configuration and Port definitionAlarm clock settingApplication fontSerial printer locationAutokey rateAutokey delaySpeaker volumeAttention (beep) soundDouble-click timeCaret blink time (insertion point rate)Mouse scaling (mouse speed)Startup diskMenu blink countMonitor depth32-bit addressingVirtual memoryRAM diskDisk cacheOk, let me know if this helps ?Thanks.
Also have no "Trickle Voltage on the Logic Board Test Point
Iv heard the APV board or Down Converter Board are the main issues on the board for failing .
Do to overheating .
this guide shows a full tear down of imac models and gives some info for part numbers .
board. Once the unit is plugged in, power flows from the AC outlet at the wall to the AC inlet on the power/analog board. From there, the power flows through the main cable on the power/analog
The iMac requires trickle voltage (+5 TRKL) in order to power- on. If you are experiencing power problems in the iMac unit, you will want to test for trickle power to pinpoint the location of the problem and to determine whether or not the power supply/analog board is functioning normally. If you have trickle power in the
cord, power-on the system using the power button on the front of the computer. If the system powers on, you can assume the AC out- let is good and the problem is with the keyboard. If the system still won’t power on, try connecting to a different AC outlet. If the unit powers on this time, you most likely have a problem with the AC outlet. If you still have no power, you may need to reset the PMU chip (power manager) on the logic board (refer to “Resetting the Logic Board” in this chapter).
Plug in the computer, but leave the iMac powered OFF. Ground the black probe on the volt meter to the logic board screw, as shown in the photograph below. With one hand behind your back, touch the red probe on the volt meter to the top pad (pin 1) at J9 (see the photograph below) on the logic board, to see if you have +5V on the logic board. A +5V reading on the logic board means the power supply is providing the necessary trickle voltage to the logic
Testing for +5 V Trickle Power at J9 on the Logic Board
meter to the logic board screw, as shown in the photograph below. Touch the red probe to C10 (see the photograph below.) The DCO voltage should measure approximately -1.2 volts with the power cord plug plugged in. The voltage will jump to 21 volts after pow- ering on the system. A reading of -1.2 volts up to +1 volt indi- cates the logic board is OK. Without a reading of -1.2 volts, verify the fuse at F901 is OK (refer to “Testing the Power/Analog Board Fuse” in this section). If the fuse is OK replace the power/analog/ video board.
Testing J7 for Voltage on the Logic Board
touch the red and black probes to the two metal points at location F901 and check for continuity (reading of “0”). If the ohm meter registers “0”, the fuse is good. If the meter registers “infinite”, the power/analog/video board should be replaced. A bad fuse is
not affected. The PMU isvery sensitive and touching the circuitry on the logic board can cause the PMU to crash. If the PMU crashes, the battery life goes from about five years to about two days if the PMU is not reset. Refer to the next topic, “Resetting the PMU on the Logic Board” for the procedure. Many system problems can be resolved by resetting the PMU chip. The PMU reset button is
1. Disconnect the power cord and check the battery in the bat- tery holder (BT1). The battery should read 3.3 to 3.7 volts. If the battery is bad, replace the battery, wait ten seconds, and then reset the PMU (refer to the next step). If the bat- tery is good, go to the next step.
2. Press the PMU reset switch (S1) once on the logic board and then proceed to step 3. DoNOT press the PMU reset switch a second time because it could crash the PMU chip.
ering the computer on. If the computer powers on, go to the next step. If the computer does not power on, there is some- thing else wrong with the computer, refer to the symptom/ cure chart, “No Power” in this chapter.
startup chime. Instead, the system will beep as explained below. Refer to “Error Beeps” later in this chapter for instructions on how to troubleshoot and repair an iMac that sounds error beeps at startup time.
The battery on the logic board controls the stored system settings, such as date and time. It is only necessary to test the battery when you can’t power on the computer, or the date and time are reset every time the AC power is removed.
The battery is also used to power the PMU chip (because the PMU chip keeps time and must always be running) when the computer is unplugged from the wall (AC power). The PMU isverys e n s i t i v e and touching any circuitry that is connected to the PMU can cause it to crash. If the PMU crashes, the battery life goes from about five years to about two days if the PMU is not reset. Once the bat- tery goes dead, the PMU will reset the time and date to 12:00 AM 1/1/04 every time the AC power is removed. To fix this situa- tion, replace the battery and reset the PMU (refer to “Resetting the PMU on the Logic Board” mentioned earlier in this chapter).
There are two part numbers in service stock for the power/analog/video board on the iMac DV computers (Summer 2000) because there are two vendors manufacturing the boards. The part numbers are XXX-XXXX and XXX-XXXX. These boards must be exchanged like- for-like.
The XXX-XXXX board (Figure 1) has a switch at location SW901 that must be set for the type of CRT tube in the computer. The switch settings are silk-screened on the board near SW901. If this power/analog/video board or the CRT are replaced, make sure to set the switch to the appropriate position (either to LG or CPT). Refer to the next page for CRT identification information.
spare part :
more spares :
Hi , hope all thia info is of use to you ,
If you need more info , you may be able to contact apple , or a service provider .
alternatively you may be able to get extra help via :