820-4924-A - No Green Light

[m3g4tr0n]

Have a 820-4924-A - with no Green light on the charger.

R7020 looks discolored and measures 31.9ohms insstead of 47ohm.

attached a picture with voltages between dc jack and u7090.

also getting a short to ground on PP3V42_G3H (L7095, C7099, C7010, C7008, ...)

took off u7090 and L7095, C7099 and short still there. didn't take anything else off.


thanks

[mon2]

Re: 820-4924-A - No Green Light

What is the resistance to ground at c7010?

The 3v42 rail is required for the one wire circuit to operate and light up the adapter green light.

You may have a shorted cap but please post the above resistance reading for this rail.

[m3g4tr0n]

Re: 820-4924-A - No Green Light

C7010 resitance to ground

001.5ohm (0.004 diode mode)

[mon2]

Re: 820-4924-A - No Green Light

PP3V42_G3H_REG goes all over the board including powers the one-wire circuit that is not being powered due to lack of 3v42 presence.

Remove the trackpad & keyboard cables and check again on this resistance.

Look around for possible liquid damaged parts that may be impacting this rail.

Something is causing for this low resistance on this line which is then forcing this rail to shut off.

Do you have a voltage injector? Do not use it yet. Others may have other advice but please post the results from the above testing.

[zpi]

Re: 820-4924-A - No Green Light

Usually these boards has damaged c7090 c7091 or c7092 when PP3V42_G3H_REG is shorted. You allways can inject 1v and check if one of this caps does not get hot

[mon2]

Re: 820-4924-A - No Green Light

Recommend to throw with Q-tip (what we use) some alcohol these tantalum caps. They are usually the bad boys that die over time. For us, we saw the alcohol evaporate quickly with a small amount of smoke with our 30A injector @ 0.9v. Found the bad tantalum in seconds.

[m3g4tr0n]

Re: 820-4924-A - No Green Light

PP3V42_G3H_REG goes all over the board including powers the one-wire circuit that is not being powered due to lack of 3v42 presence.

Remove the trackpad & keyboard cables and check again on this resistance.

Look around for possible liquid damaged parts that may be impacting this rail.

Something is causing for this low resistance on this line which is then forcing this rail to shut off.

Do you have a voltage injector? Do not use it yet. Others may have other advice but please post the results from the above testing.

The test was done on the board only nothing connected. I didn't see any liquid damage. I'll look again after work.

I have a bench supply.

[m3g4tr0n]

Re: 820-4924-A - No Green Light

Usually these boards has damaged c7090 c7091 or c7092 when PP3V42_G3H_REG is shorted. You allways can inject 1v and check if one of this caps does not get hot

If they are damaged should they not short to ground?

[m3g4tr0n]

Re: 820-4924-A - No Green Light

Recommend to throw with Q-tip (what we use) some alcohol these tantalum caps. They are usually the bad boys that die over time. For us, we saw the alcohol evaporate quickly with a small amount of smoke with our 30A injector @ 0.9v. Found the bad tantalum in seconds.

My Bench supply only has 30v 5A. Do you mean short killer? Don't have one of those yet.

[mon2]

Re: 820-4924-A - No Green Light

Yes, short killer. We have the TS-30A which is working well. We dialed up to 0.9v and applied onto the rail. The point of contact would spark a bit and then we removed the injector probe. This surge pulse (a few times) was ample to locate the shorted cap for our first time use about a week ago. Very very helpful tool.

I think you can do the same with your power supply.

Lower the voltage to 1 volt on your power supply and apply onto the same rail of interest.

Connect black to ground.

What is the current draw once you attach the power supply probe (+; Red wire)?

Assuming that the current draw will spike, check for the caps that may be heating up. The alcohol will help a low and the heat from the bad cap will make the alcohol smoke up / dry up very quickly.

With tantalum caps, when they die, they present a short circuit to ground. Useless caps in my opinion. We have 1M++ of our products in the field and rule #1 for our designs...NO TANTALUM CAPS. Have devices with 10++ years of service and still kicking. Can you imagine $$ equipment just dying over a cap? If I recall correctly, Japan had a ban on tantalum caps ages ago. Can really appreciate their point of view.

[mon2]

Re: 820-4924-A - No Green Light

I do not believe that you have a short on c7090 c7091 or c7092 since the voltage on this rail remains within range with Pin 1 of D7005.

If the value @ pin 3 of D7005 is very low then yes, one or more of these caps on this leg is shorted and drawing too much current, hence a power rail drop which in turn does not allow for the 3v42 regulator @ U7090 to turn on.

Please confirm the details on this leg but believe you are ok here.

I think you may want to consider the voltage injection @ 1V on the PP3V42_G3H_REG line which was showing a low resistance to ground. Then review which cap is heating up. My bet will be on the polarized tantalums (assuming that the board has been cleaned up enough from any possible liquid damage).

Locally we get the real confessions from the customer after we inform them of the neon green oxidation of the PCB, etc. - 'oh yeah, my sweetheart daughter spilled this or that...' - no kidding. Alcohol is great at cleaning up most of such damage.

You may want to consider a professional ultrasonic cleaning tank to handle small / mid size PCBs. We purchased 2 such units - one for phones and one for macbook size boards. This along with the cleaning solution will do a nice job to remove spills off the board. Many on Aliexpress / Alibaba - we went direct to the mfr of the cleaners.

[m3g4tr0n]

Re: 820-4924-A - No Green Light

Update: Macbook is working.

Voltage injection on the PP3V42_G3H_REG line

1V 1A - nothing got warm or hot (0.5xxA)
2V 1A - nothing got warm or hot (0.5xxA)
2V 2A - nothing got warm or hot (0.5xxA drops to 0.2xxA)

3V 2A - was drawing all 2 amps. i kept connecting and disconnecting the ground cable from the bench supply and on the 4th try it stayed on 3v and the amps dropped to 0.2A.

checked the caps and inductor that were shorting before and theres no more short.?????? where did the short go?? only thing i did was put IPA on U7090 and it's surrounding components.

pluged in adapter got a green light for 2-3 seconds then it stays on orange. Logic board with and without battery

[mon2]

Re: 820-4924-A - No Green Light

Excellent.

The injection removed the short. One or more of the caps internally no longer have this short circuit event.

Consider to source a high current injector and keep the voltage low at 1v or close to. That is what we understand is the proper procedure. TS-30 is the model we purchased which works fine. Only one small complaint is that the display is not as bright as the videos nor advertisement.

There are a number of similar looking cloned injectors on AliExpress.

For your 3v42 rail, your process was fine. Just keep the voltage to a safe level.

For us, the current would peak to 8A while the cap was shorted.

Good work!

[m3g4tr0n]

Re: 820-4924-A - No Green Light

@mon2 thanks for your help.

i'll probably get the short killer in the end of the month.

i wasn't gonna inject more than 3v.

what about the orange light, is that normal? never had a mac before.

[mon2]

Re: 820-4924-A - No Green Light

Orange light is to inform the user that the macbook is charging the battery.

Leave the unit plugged in and monitor the battery charging progress bar at the desktop. After 10-20 minutes, do you see the battery level increase?

There is a battery meter tool included with the operating system that will show the battery level.

If after charging, the macbook can continue to run on battery then all good.

If the macbook powers off with the adapter removed then you have a dead battery and the battery must be replaced.

Once the battery is 100% charged, the adapter will turn green.

[piernov]

Re: 820-4924-A - No Green Light

200mA drawn on PP3V42_G3H is still pretty much a partial short to ground. SMC can cause this (but still another component could be the culprit). It should warm up more than usual.

[m3g4tr0n]

Re: 820-4924-A - No Green Light

it's charging now.

if SMC was shorted, would i need to use one from the same board model?



thanks everyone

[zpi]

Re: 820-4924-A - No Green Light

Yes