247it
Member
"Im an old guy, still working in IT, enjoying microsoldering and generally fixing anything i can get hold of"
Last Activity: 04-22-2025, 01:51 PM
Joined: 03-03-2023
Location: Bristol
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So, im thinking a something starting or a power rail being created into a short is causing a protection condition, im not seeing heat because the protection is very rapid, so would anyone know what power rails to check further down the line that would cause a complete power cycle? if i can find the rail i may be able to inject an appropriate voltage and current to identify the short, or is this a bit simplistic. -
Lowest coil resistance to ground is 6 Ohms, highest is .5M, does that seem like CPU is ok?
three things get warm,
CPU heat sink,
U7210 @ 40C, (replaced it, still warms up)
U7270 briefly (1sec) warms while CPUSA_DRVH is at 4.4 volts (replaced U7270 also)...Leave a comment:
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Hi mon2, thanks for your help,
I managed to get a like new track pad and ribbon for £10, not too bad, i also picked up a drilled but tidy doner board for £13, so have some spares, I have replaced the U9000 chip as i poorly reflowed it a year ago (last time i worked on the mac) but still the same,
its a long shot but you may know what the below means,
Power meter starts at 5V then jumps to 20V - current climbs to 600ma and stays stable for a while, then the amps jump to 800ma, reset then happens immediately, meter reads 0 amps 20V and the cycle starts again,...Leave a comment:
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Thanks for the advice, Amazon have them for £20, the main board ribbon is also toast, one of the pads has rotted to nothingLeave a comment:
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Everything checks out fine, no shorts and voltages are all stable, I saw a post of yours [URL="https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-laptops-tablets-and-mobile-devices/3157188-macbook-a1989-missing-rails-pp3v3_s5-and-pp1v8_s5"]MacBook A1989 missing rails PP3V3_S5 and PP1V8_S5 - Badcaps[/URL] my trackpad is very liquid damaged, im guessing this could be the problem?Everything checks out fine, no shorts and voltages are all stable, I saw a post of yours [URL="https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-laptops-tablets-and-mobile-devices/3157188-macbook-a1989-missing-rails-pp3v3_s5-and-pp1v8_s5"]MacBookLeave a comment:
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Thanks mon2, ill work my way through...Leave a comment:
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Macbook Pro 13" A1989
Hi all, I picked up a MacBook pro 13" with a A1989 mainboard, it suffered a little liquid damage around the CPU power section,
USB C switches to 20V 0.17 amps, this rises to .6 amps, stays that way for 30 seconds or more, then drops to 0 amps, 20V is maintained, fans spin at full speed for 1 second then the cycle starts over, CPU warms up slightly, mosfets U7210 heats to 38C and U7220 briefly heats and then goes cold at the start of the cycle,
Could anyone point me to some posts on what voltages to check and where / how to check for shorts and the places to often check?... -
If anyone is interested, this problem was a corrupt EEPROM, there is some talk that the PD controller (TPS65994) doesn't need programming, it does 100%, if the code in the EEPROM goes bad, the PD chip will not start and is inaccessible,
Massive credit to SMDFlea, thanks man! donation to the site made, link to the solution here.Leave a comment:
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Still a Legend
should i put a link to the solution in the hardware troubleshooting post i have open? Noob here so not sure...
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SMDFlea you are an absolute genius! I would love to know how you figured that out,
LEGEND!
[ATTACH=JSON]{"data-align":"none","data-size":"small","data-attachmentid":3599769}[/ATTACH]...Leave a comment:
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Thanks,
Main firmware R1SET59W(1.30)
PD Hardware ID = 677ee0c5-bedd-4116-ac65-056912e78a79
Version FFFFFF00...Leave a comment:
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Hi SMDFlea, huge thanks for the reply, yes, the laptop does charge and run fine but only charges at 5v 3 amps,
I tried what you suggested yesterday but will have another go today,
the main bios is the latest available as of yesterday, the PD firmware seems to install in windows, however when the computer restarts the firmware doesn't seem to install, just boots straight into windows,
is the bios supposed to interrupt boot to install the PD firmware similar to the main bios install?...Leave a comment:
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PD Controller TPS65994AE EEPROM
[FONT=Aptos]Hi, I have a ThinkPad E15 G4 I am working on for fun, the PD chip is not talking to the charger, it's stuck at 5v, I have replaced the PD chip three times now (new chips) and always the same result, I have checked for shorts, correct voltages on the PD IC etc - 5v 3v, and the 1.6v on the cc lines, even replaced the USB C port protector IC and the charging port,
The PD IC has a EEPROM connected directly, it's the one in the image attached, I assume the PD chip will not start without some initial commands stored in the EEPROM, the PD IC never shows in device manager, i backed... -
Hi mon2, new PD chip is in, in diode mode red to ground black to cc1 and cc2 reads .432 there is 5v on the vbus,...Leave a comment:
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[FONT=Aptos][FONT=Arial]Thats great info, thank you, the PD chip is out at the moment, i hope to get the new one Sunday or Monday, I'm seeing 5v on TPS65994AE BGA pad - pin H8 - TBTA_VBUS20,
i do recall seeing 1.6V on one CC line and .4V on the other, spin the USB C plug over and the voltages reverse,
ill have a look at the analysers, sounds like an interesting tool to have,
i had a slight concern regarding EEPROM that the PC chip connects to (CAT24C256WI) i took it out and read it so assume all good, i may be getting ahead of myself though
appreciateLeave a comment:
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Thanks FriedFred, makes sence, i have learnt afterwards the PD chip has a charge pump of its own, it looks like that is used to raise the gate voltage higher than 20V so the MOSFET conducts correctly, still stuck at 5v at the moment, i have a new PD chip on the way plus a new port protector IC just in case, everything else seems ok,...Leave a comment:
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Thanks FriedFred, the battery is 11.1V there is a boost converter on the mainboard, 5 volts on the usb c (on the meter) 12v charges battery, not sure why the buck-boost, maybe to suppy the battery mosfets gate with more than 20 volts when running corrrectly,
anyone know the buck-boost purpose?
[ATTACH=JSON]{"data-align":"none","data-size":"medium","data-attachmentid":3588766}[/ATTACH]...Leave a comment:
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Thanks FriedFred, battery seems ok, holds a decent charge anyway, just takes forever to charge at 5 volts 3 amps, even if the battery isnt installed the voltage from the charger never goes over 5 volts, should be 20 volts at 3 amps, tried different chargers and a big power bank but 5 volts is the max that the power supply goes to, its a real tricky one but im enjoying learning, thanks for your input...Leave a comment:
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[SOLVED] Lenovo E15 G4 charging at 5 volts
[FONT=Aptos]Hi everyone, I hope someone has some pointers for me, for fun I'm trying to repair USB C charging on a Lenovo E15 G4 laptop, I brought this back from work as it was written off, I successfully replaced the USB C port some time ago, however it was broken again by the end user, this time the port was twisted off the board but the pads survived,[/FONT]
[FONT=Aptos]I have installed another port but the charger never gets the ok from the PD chip (tps65994ae) to go to 20 volts, it does charge slowly using the boost converter to step up the charging voltage but takes hours, voltages...
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