Acer Aspire M3970
Motherboard code: IPISB-VR REV 1.01
PCH - HM67
There was a trigger when I examined the motherboard. but the voltage was cut off. maintenance on the motherboard in another service.
I examined the bios chip is broken. BIOS programmer - chip read error message. i bios chip replace.
there was a result. this time the motherboard started normally. RAM +1.5v/ PCH +1.05v/ +1.8v - OK
CPU Core and GFX Core voltage - 0V
this time I started to examine the cpu circuit . CPU PWM - NCP6151
main voltage and enable signal normal. VRM_PWRGD - 0V (this is normal . because the circuit is not working)
this motherboard has 4 phase main coil. one coil GFX Core (intel hd graphic)
there is also an Buck MOSFET Drivers for core voltages (NCP5901)
later i realized that the Enable signal is too low ( +236mV) . this signal is normally +5V DRVON - generates its signal in CPU PWM. I measured CPU PWM DRVON signal
this signal is low due to another reason. i remove PR330. (2.2ohm)
I started the motherboard and the result is good. DRVON signal +5.0V OK
There is no problem in its CPU PWM then.
I applied a method. Buck MOSFET Drivers (NCP5901) - I cut the activ signals . Remove PR212 (0 ohm)
if no result, I would apply this method for the other PU15, PU16, PU17, PU18, PU19 and PU20(GFX)
I first applied this method PU14
Motherboard has started. DRVON enable signal is active (+5V). Motherboard gave beep signal 4 times. cpu on motherboard was broken
I wasn't sure the CPU was running because the motherboard was not working normally.
Replace CPU and worked CPU Core +1.04V and GFX Core Voltage +0.4V
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狗仔卡
发表于 2020-4-17 04:39:49
支持！
反对！
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