SoftMachine Posted December 1, 2022 Report Share Posted December 1, 2022 (edited) I've read that this could be a failed memory module but I'd like some more info before I go ahead and start replacing those. I've seen some things that conflict with that info; LPC pin 5's trace, video encoder, etc. random nonsense. The board looks clean, I can't see any corrosion or trace damage, caps looks fine, I scrubbed it with IPA especially around the RAM and had no luck. Maybe someone else that's dealt with this before can share their experience. Edited December 1, 2022 by SoftMachine Quote Link to comment Share on other sites More sharing options...
KaosEngineer Posted December 1, 2022 Report Share Posted December 1, 2022 The signal on pin #5 of the LPC Debug port is LRESET# (aka MCPX's PCIRST# output). This signal connects to several other peripheral chips to initialize them during startup. For the RAM, the signal goes from the LPC Debug Port's pin #5 to several line drivers/level shifters whose output then connects to all of the RAM chip's CKE (clock enable) inputs on pin #53 to properly initialize them during system reset/startup. As I understand it if this active-high CKE pin is not pulled low then high at power-on, the RAM chips don't get initialized to function properly. Therefore, when the RAM is tested during system initialization, a data error is detected. The CPU tells the System Management Controller (SMC) that a RAM error has occurred which then indicates detection of this RAM error by flashing the Eject ring RED and ORANGE and halts the remainder of boot process. The RAM chips may be good but without the proper startup sequence, no go. 1 1 Quote Link to comment Share on other sites More sharing options...
Bowlsnapper Posted December 1, 2022 Report Share Posted December 1, 2022 5 hours ago, KaosEngineer said: The signal on pin #5 of the LPC Debug port is LRESET# (aka MCPX's PCIRST# output). This signal connects to several other peripheral chips to initialize them during startup. For the RAM, the signal goes from the LPC Debug Port's pin #5 to several line drivers/level shifters whose output then connects to all of the RAM chip's CKE (clock enable) inputs on pin #53 to properly initialize them during system reset/startup. As I understand it if this active-high CKE pin is not pulled low then high at power-on, the RAM chips don't get initialized to function properly. Therefore, when the RAM is tested during system initialization, a data error is detected. The CPU tells the System Management Controller (SMC) that a RAM error has occurred which then indicates detection of this RAM error by flashing the Eject ring RED and ORANGE and halts the remainder of boot process. The RAM chips may be good but without the proper startup sequence, no go. Holy SHIT, Kaos. That was like watching a Nova documentary... Badass. 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.