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820-2879 green light, not turning on and not charging

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  • ytesfay80
    replied
    Okay thanks.

    Leave a comment:


  • 2informaticos
    replied
    Good luck to find a new MCP.
    Is probably better to trash this board...
    It still has more issues; not charging is not related with MCP.

    Leave a comment:


  • ytesfay80
    replied
    Okay I removed the thermal paste from the U1400 chip and confirmed that it is getting really hot when I put 2.6v on the PP3v3_s5 line.

    That means the chip would need to be replaced to fix this right?

    Leave a comment:


  • ytesfay80
    replied
    I removed L7220. Pin 1 was showing 0.002v and Pin 2 was showing 0.07v in diode mode so I went to resistance mode to ground and Pin 2 was OL and Pin 1 was like 5ohms so I injected 1v into Pin 1 and couldn't feel anything getting warm so I went slowly up towards 2v(shows 2amps going through) and the only thing I feel getting warm is U1400 and the opposite side of the board where u1400 is. I put alcohol on those areas and nothing burned away unusually fast.
    Last edited by ytesfay80; 03-22-2017, 08:48 PM.

    Leave a comment:


  • 2informaticos
    replied
    I'm wondering how can you read 280 value in a 200 scale...
    You've probably used auto-range, not 200K selected.

    Lift one pin of L7220 and look where the short is.
    Be aware, this will not completely discard TPS!
    Inject voltage starting with 1V, maybe less; keep the current under the limit of your lab supply.

    The short appeared when you powered up the board without TPS; don't do that again...

    Leave a comment:


  • ytesfay80
    replied
    Red probe on Pin 1 of L6995 black on ground in resistance mode 200k scale shows 280kohms.
    I removed Q7221 and measured.
    L7220 was showing nothing but pulses of 0.05-0.13v.
    L7260 was showing no voltage at all.

    L7220 in diode mode was 0v to ground on both sides.
    L7260 was 0.43v to ground on both sides.

    Also now I am seeing 3.38v on Pin of R7273 where before I was getting 0v on it.

    Should I remove L7220 and see which side the short is on?
    Last edited by ytesfay80; 03-22-2017, 03:50 PM.

    Leave a comment:


  • 2informaticos
    replied
    Check resistance to ground at L6995, in 200k scale.
    Remove Q7221 and tell us voltages at L7220/60 when PPBUS_G3H is high.

    Leave a comment:


  • ytesfay80
    replied
    I replaced the ISL6259 from a donor board and it is still fluctuating as I said previously. I also put flux and heated the SMC to rid of any corrosion under it and that still didn't solve this. Pins 17/18 27/28 resistance and traces are fine.
    Any other ideas dukefawks 2informaticos ? I may have to refund the customer and send this back.
    Last edited by ytesfay80; 03-22-2017, 05:26 AM.

    Leave a comment:


  • ytesfay80
    replied
    Okay I removed L6995 and the short was on Pin 2 side so I injected voltage there and the current was showing around 1 amps then it just started showing 0 amps and the short was gone. I put L6995 back on along with U6901 and now the green light is back.
    PPBUS_G3H is showing 12.58v then it will just go to 4v and quickly down to 3v then back to 12.58v for a couple seconds then repeats.
    SMC_PM_G2_EN is back at 3.4v.
    C7273(PP5V_S5_LDO) pulses from 4.7v and goes down.
    C7270(5V3V3S5_REG3) pulses from 3.33v and goes down as well.
    I need to get PPBUS_G3H stable as I did before. I'm not sure if these ISL6259s that I am getting from my spool are bad because I've replaced a few different ones and sometimes I get different voltages on PPBUS.

    Also, R5260 is still showing 0v to ground in diode mode on both sides.

    Leave a comment:


  • 2informaticos
    replied
    "So I removed the TPS51125 from the board and plugged the charger in"
    So you may have to trash the board now.
    I suppose one high-side MOSFET got burnt...
    Never-ever power up a board leaving MOSFETs from a buck converter with the gate floating!!!

    Leave a comment:


  • dukefawks
    replied
    Crap under SMC? Shorted SMC? Inject voltage on 3V42 and see if anything heats up.

    Leave a comment:


  • ytesfay80
    replied
    Do you know how SMC_PM_G2_EN could be present before I replaced the ISL6259 but not anymore?
    I have a green light on the magsafe.
    ADAPTER_SENSE is 3.38v.
    SMC_RESET_L is 3.4v
    U5010 measurements are fine.

    I've tested with 2 know good dc-in boards.

    Update: So I removed the TPS51125 from the board and plugged the charger in to see if SMC_PM_G2_EN would come on but it didn't and when I put the chip back on and plugged the charger in the light was dim green and SMC_RESET_L is 0.15v. I don't know what is going on. I've plugged in both DC-in boards and they both are dim green now.

    2nd update: I looked around the SMC and found R5260 was corroded and in diode mode 0v to ground on both sides. I removed it and the pads are still 0v to ground in diode mode.
    Pin 2 of R5071(PP3V42_G3H) was also 0v to ground in diode mode. Removed R5071 along with U6901 and still shorted to ground.
    Last edited by ytesfay80; 03-20-2017, 10:42 PM.

    Leave a comment:


  • 2informaticos
    replied
    Don't be so sure...
    In the first DC board was fucked some resistor on ADAPTER_SENSE line, which means overvoltage; maybe protection diode.
    That could slightly affected SMC, which still worked, but now missing SMC_PM_G2_EN could be result of that.
    Check SMC_RESET_L first, if no light on magsafe.

    Leave a comment:


  • ytesfay80
    replied
    Okay so I replaced the ISL6259 and now PPbus_g3h is a steady 12.56v.

    U7200 was still not getting steady voltage on the VDD Pin so I replaced the TPS51125 with a brand new one and still that didn't solve this.

    Now when I checked SMC_PM_G2_EN on R7273 there is 0v there, the resistance is around 95k and in diode mode SMC_PM_G2_EN is 0.45v .
    U7840 voltages
    Pin 1 - 3.4v Pin 2 - 0v
    Pin 3 - 0v Pin 4 - 3.38v
    Pin 6 - 0.98v Pins 7/8 - 0v

    Pins 8/17 of U7200 are still fluctuating and aren't at the proper voltages.

    I'm sure this can be fixed because I fixed this this board for the customer a couple of weeks ago. It was not turning on so I replaced the DCIN board and it was working again. After a week they told me it would no longer turn on.



    Leave a comment:


  • ytesfay80
    replied
    I measured as soon as the charger was plugged in with my fluke 115 multimeter and pin 17 of u7200 was 4.24v and it quickly goes down.
    Pin 8 was 2.78v and it quickly goes down towards 0.6v then jumps back up to 2.78v and repeats.
    SMC_PM_G2_EN is 3.4v.

    These measurements are with the original TPS51125
    Last edited by ytesfay80; 03-19-2017, 09:34 PM.

    Leave a comment:

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