820-3115 - One beep every 5 seconds. Ram definitely installed.

[gcain]

Customer says it works sometimes but generally just gives the one beep every few seconds.

Have tried wiggling the ram and checked the seating. All looks okay. Fresh ram made no difference.

Any suggestions?

 

[jadao]

Hi, check and compare pch smbus connections R5201/R5200 diode mode, continuity and resistors value. Anything on the bus may cause the one beep error. More often the led backlight. If diode mode is low try removing R9753/R9757 and see if diode mode on smbus come back to normal value.

Of course you have to make sure ram is working and detected.

 

[gcain]

R5200: 0.647k
R5201: 0.619k
These are supposed to be 1k. Don't think I have ever seen resisters read low... so must be reading the circuit. A working board I have here reads 1k on both resistors.

Diode mode on R5201::2 = 0.065
R5200::2 = 0.150

 

[dukefawks]

Problem on the SMBUS. Check all components connected to the bus. Backlight chip is a common suspect.

 

[gcain]

Can I pull an LP8550 from a donor board or does it need to be a new one?

Haven't done a BGA chip like that before.
Before I do that though I am going to take Jadao's suggestion and remove R9753 & R9757 and check for changes.


Edit: The board just suddenly chimed and worked fine, reconnected power and back to the beep. :/

 

[dukefawks]

Yeah pull those resistors first to see if it fixes the issue.

 

[gcain]

I removed R9753 & R9757, but still get the single No Ram beep.

 

[jadao]

So diode mode values are still low on the bus?

Something else on the bus is causing the short.
look at page 48 "SMbus connections".

Please check them all, same principle as you did for Backlight chip. Remove resistance if any or the chip to isolate the bus. And check each time if diode mode value become higher.