Re: Lenovo B50-45 dead after APU change
Nothing visible under magnifier.
I can't believe that 2 of 2 new APUs could be bad the same way...
homeless_cz
Member
Last Activity: 02-02-2025, 11:57 AM
Joined: 10-01-2017
Location: Prague
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Lenovo B50-45 dead after APU change
Hi, I'm a bit despered of this laptop.
The board is Compal LA-B291P which worked but AMD APU was defective causing random sudden reboots.
So I decided to replace APU E1-6010 with better one compatible.
First I updated bios to latest, all OK. Then I desoldered old APU and put new one A8-6410 - the same platform "Beema" . Since that time no init, black screen.
All voltages OK, checked power sequence, all signals between EC and APU are OK, susp# signals goes high, SPI has read activity, the only thing I miss is Backlight ON and a picture.
Today I decided to... -
Re: IC chip getting hot when turn it on
These caps are between common groud and audio ground, they are not related to ALC chip directly.Leave a comment:
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Re: Questions about EC's(KBC)
I have read on russian forum about ITE858x, when is blank (new) , on first power-on it reads EC block from SPI and it programs itself. When is taken from a donor board where previously used, it doesn't do that and needs to be programmed or erased externally.My experience is with few 8585e and 8586e, after replace with new chip it worked this way on Asus boards.Leave a comment:
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Re: Compal LA-6901P : No power with battery alone
Both cases battery and adapter pin 3 is clear, GND, pins 1 and 2 almost 0. In battery mode PQ9 gets short pulse to base and it sets gate of PQ5 to GND via PR15 , this opens PQ5 to pass the battery voltage to system. When you plug adapter, then VIN = 19V which closes PQ5 via PR16.Leave a comment:
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Re: Compal LA-6901P : No power with battery alone
??? You should have 3,3V on that button.
Anyway here is schematic -> [url]https://cdn.badcaps-static.com/pdfs/5a47d0346798be2b2719baa12dee6b89.pdf[/url]
Focus on page 48 and check mosfet PQ5 and other parts related to its Gate.Re: Compal LA-6901P : No power with ...df[/url]<br />...Leave a comment:
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Re: Lenovo G50-70 - power on problem
That's the problem. PROCHOT# is signal of overheated CPU, overheated voltage regulator and under voltage protection. It can't be 0 for normal work.
Check everything related to PROCHOT# and find what generates 0 and blocks normal work.
On page 47 is nice diagram of power-on sequence....Leave a comment:
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Re: Lenovo G50-70 - power on problem
Strange.
101 must be 0 to chip select, 103 is data output from SPI chip, 105 is clock for SPI chip
Is SPI chip OK?
Pin 71 is ADP_I from charge controller, shoul not be 0 but analog 0,7 to 2,7V I think depending on charge current.
And pin 80 PROCHOT?
Is ITE well soldered?
Anyway you should check page 53 of schematic. Check all mosfets.Leave a comment:
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Re: Lenovo G50-70 - power on problem
This means ITE hasn't met his requirements to power on the system.
LID SW is OK -> LID OUT is OK, AC present is OK. PWR sw is OK.
When you press PWR button, pin 110 goes down and 86 should go down too, then 97 high, 93 high, 79 high and all other SUSP# and SLP# signals should go high too.
Check the same way:
108, 71, 14, 111, 112,
If you have a oscilloscope, you should check pins 101,102,103,105 if there is some communication with SPI flash rom.
Does the laptop at least charge the battery? Is it indicated...Leave a comment:
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Re: Lenovo G50-70 - power on problem
Is 3V_ALW_PCH present ? If yes then you have to check what happens on IT8586.
Does it have +3VALW and +3VS ?
Check this in ready state and then after pressing pwr switch:
PWR SW on pin 110
LID SW pin 109
AC present pin 128
PCH_PWR_EN pin 97
PCH_PWROK pin 99
PBTN_OUT# pin 86
MAINPWON pin 79
EC_LID_OUT# pin 2
EC_RSMRST# pin 93Leave a comment:
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Re: Enermax PRO 82+ 525W repair
Well I really appreciate you share these conclusions and spent lot of time with writing these long posts
It is all interesting. I'll consider to change primary caps to 450V ones even if they are OK, but are about 8 yrs old.
You were lucky with a thermistor, mine was shorted and blown up like a grenade, only legs in PBC stayed
Leave a comment:
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Re: Enermax PRO 82+ 525W repair
You are right, first I tried it with no load, voltages were OK, then I tried to add some old HDDs which made too low load for proper regulation. Today I tried to add 22 Ohm power resistors to each rail and everything looks to be OK.
The only similar spare I had is 2N5401 with lower hFE, but this shouldn't be a problem.
I'm asking myself the same question.
I think you are absolutely right and in my case the destruction started with defective TH1. PCB under TH1 is burned....Leave a comment:
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Re: Enermax PRO 82+ 525W repair
Thanks for suggestion guys. I had a suspicion that primary part works for 1 half wave only, I mean 1 switching cycle. I was checking what happens after power on and I found out that secondary monitoring IC PS231S turns off PFC IC CM6802 after a while. So for the 3rd time I checked all primary parts and found 1 dead transistor which I missed before. CM6802 controls via this transistor the gate of 1 PFC FET. So this confirmed my suspicion.
After replace of this transistor PSU started to work normally, but I didn't have exact replacement. At this...Leave a comment:
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Re: Enermax PRO 82+ 525W repair
Output power diodes OK, all other diodes OK, caps no shorted, good capacity.
I can´t understand why it works when I unplug AC cord only. If I leave AC cord connected and just switch off the main switch, which brakes the phase wire, it doesn´t work.
I have to unplug AC completely and then power on by green wire, then it works until primary caps discharge. WTF?Leave a comment:
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Enermax PRO 82+ 525W repair
I´m trying to repair this PSU.
One day I powered on my PC and I heard a blow.
So I disassembled the PSU and found burned out thermistor and 1 MosFET in PFC circuit.
So I replaced both FETs K20J60T to K20J60U but I didn´t know what thermistor was there, so I put SCK055. And new fuse of course.
Now the PSU does strange things. +5V SB works normally, but when I power on(green wire to GND), output voltages goes up for half second. And then nothing.
If I unplug AC cord and then power on, output voltages are OK for 3 seconds until primary capacitors discharge.
PFC...Last edited by homeless_cz; 09-29-2018, 08:46 AM. -
Re: asus x550LD rev 2.0 bios needed
Many thanks for the dump, helped me a lot.Leave a comment:
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Re: New Members - please post your introductions here
Hi,
my name is Milan, I'm from Prague, Czech repulic and I'm trying to get deeper into laptop boards repairs. I have a few years of experience with electronics repairs but I am in no an expert.Leave a comment:
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