imac 820-3588-A keeps beeping with or without RAM.

[LaptopRepair]

Working on one imac 27. It keeps on beeping with the RAM plugged or without.

VDDSPD at pin 199 of the RAM slot is present 3V3.

PPDDRVTT is also present 0V75.

I am wondering if I am on the right direction. Please need a quick answer!!

Greeting

 

[Alan.L]

both slots beeping or just one?

is it 3 beeps?

 

[LaptopRepair]

Both of them.

 

[dukefawks]

One beep or 3 beeps? Using DDRL RAM?

 

[LaptopRepair]

One beep then stop then one beep then stop continuously. I wanted to upload a video when to see that, but it is not possible as I see..44

 

[Alan.L]

buy one of this, if some led doesn't lit up then you have bad soldering joints
1Pcs DDR3 memory slot tester card with LED for laptop motherboard Notebook AS

 

[LaptopRepair]

I need some troubleshooting method by use of the schematics Alan L. Not a try and error way. But thanks anyway for trying to help.

 

[dukefawks]

One beep can pretty much be anything. It can be not recognizing RAM but it can be 100 other things. Any history on this machine?

 

[LaptopRepair]

Customers was using it and power it off next day didn't want to come on only beep.

Can you just give me an indication where to begin with troubleshooting? At which stage should we begin with testing signals?

 

[dukefawks]

The only thing you can do is diode mode/resistance to GND/voltage on both SMBUS_PCH lines.

 

[LaptopRepair]

what kind of voltage do I expect there on SMBUS_PCH_CLK and SMBUS_PCH_DATA?

 

[LaptopRepair]

3V on both lines

 

[dukefawks]

I asked more than just voltage.....

 

[LaptopRepair]

Can you be more specefic?

 

[LaptopRepair]

Correction on the above information concerning the VTT voltage, it is 0V67 instead of 0V75. Will it matter?

 

[dukefawks]

0V67 is fine as that is half of 1.35V for the DDRL RAM.

How can I be more specific if I ask for diode mode and resistance to ground on both SMBUS_PCH lines?