820_2530-a

[Anterweb]

I Know this is an old machine now, But this one is much loved and in amazing condition for it's age and I would love to get this one going again.

Green Light on magsafe / No power on. no fan spin

No liquid or corrosion board looks mint! it just stopped turning on.


PPbus_g3H =12.55v
PP3v3_s5 3.30v

All -S5 voltages seem to be present but I have no _S3 voltages at all!

Trying to figure out where _S3 Voltages are created from Schematic and it looks like its U7200???

U7200 seems to have_S5 showing up but no sign of any _s3 Voltages.

Any help much appreciated,

And yes,m Im using the correct Apple magsafe charger

 

[2informaticos]

This is MCP platform; only turns on pressing power button.

Do you get L7770 voltage?
Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L.
If present, check for pulse at PM_SLP_S4_L (at same time).

 

[Anterweb]

Do you get L7770 voltage? - Yes , - 1.064v , Sorry I had measured this and had it in my notes but missed it when typing my post,

Trigger SMC_ONOFF_L , Can I do this by using the power on pads as shown here? -https://www.rdklinc.com/poweronpads/16

 

[2informaticos]

You can use R5015/16 pads, instead of power button.
We already have the information about how to bypass power button on the forum.

HOW TO collection

I hope this "How to" collection will help our members. I will possibly modify this post in time, if updates available. Trigger SMC_ONOFF_L (PMU_ONOFF_L): It reffers to simulate power button function, when the keyboard is not connected. We need to do this when we work with the board...

boards.rossmanngroup.com

 

[Anterweb]

Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L. = Yes


If present, check for pulse at PM_SLP_S4_L (at same time) yes goes to 3.3v

 

[2informaticos]

PM_SLP_S4_L pulsing, or remains at 3V?
If you only get a pulse, test starting in SMC bypass mode.

 

[Anterweb]

Remains at 3v.

 

[2informaticos]

This signal controls S3 voltages.
Also check if PM_SLP_S3_L stays high; it controls S0 state.

Any other big coil, apart of L7000 and L7220, get voltage?

 

[Anterweb]

So going over the board under the scope to check for voltages from your last post something caught my eye, pin 4 on J5713- keyboard ribbon connector, - pp3v42_g3h diddnt look right. To the naked eye it looked missing under the scope it was there but kinda weird not seen anything like it before, so I swapped J5713 for one from a donor board and boom. Booted first time!

Tested with a spare keyboard and It all works sweet! (orderd new keyboard)

Fixed and thank you!