Laptop motherboard repair does not take the code
mahmoud
We refer here not to go yard, provided that CPURST # and CPUPWRGD have been normal. If CPURST # and CPUPWRGD not normal output, not in the scope of this lesson. Note that some machines if CPURST # pull-up resistor is not connected to the VCCP, the general need to install the CPU to normal output CPURST #, because they can not use the dummy load, to bring trouble to our testing, the general need to control point map, to find ICT use CPURST # test point. CPUPWRGD not affected, you can still use the dummy load measurements.
If some models do not install CPU power-down (such as T40), you can try to short the pins of the CPU of the remote temperature measurement method to use dummy load.
If some models do not install CPU power-down (such as T40), you can try to short the pins of the CPU of the remote temperature measurement method to use dummy load.
CPURST # test is a very important point. In general, CPURST # If the normal output voltage of the entire board that has normal output. But there are exceptions, models with different models, some machines in CPURST # after the election, there might still be voltage did not produce. CPURST # has been generated in the case, to measure the voltage of the board is still necessary, at least to a large amount of inductance of the output voltage again.
CPURST # can not only characterize the normal output voltage, the DMI-based motherboard is concerned, it can be characterized by the DMI bus connected properly, the maintenance is concerned, this can save us the measurement of DMI resistance, reducing the workload. But the motherboard does not apply Hublink architecture.
When CPURST # normal output, the focus of the next test should go into the LPC bus, because the CPU wants to read the BIOS, LPC is a necessary channel. The FSB, DMI (Hublink) as too fast, useful information can not be obtained through the oscilloscope.
In general, if the LPC moment no action, the focus should be placed in the CPU test working conditions. If there is an instant action, the focus should be placed north and south bridge test, EC and BIOS above, of course, including LPC’s own resistance to the ground.
The CPU test points, in addition to the foregoing CPURST and CPUPWRGD, as well as test points to be measured:
CPURST # can not only characterize the normal output voltage, the DMI-based motherboard is concerned, it can be characterized by the DMI bus connected properly, the maintenance is concerned, this can save us the measurement of DMI resistance, reducing the workload. But the motherboard does not apply Hublink architecture.
When CPURST # normal output, the focus of the next test should go into the LPC bus, because the CPU wants to read the BIOS, LPC is a necessary channel. The FSB, DMI (Hublink) as too fast, useful information can not be obtained through the oscilloscope.
In general, if the LPC moment no action, the focus should be placed in the CPU test working conditions. If there is an instant action, the focus should be placed north and south bridge test, EC and BIOS above, of course, including LPC’s own resistance to the ground.
The CPU test points, in addition to the foregoing CPURST and CPUPWRGD, as well as test points to be measured:
Clock is first measured the CPU bus clock. Upgrade the CPU bus clock speed quickly in recent years, the frequency has reached 200M. Caused to the equipment replacement maintenance personnel on the pressure. If the oscilloscope bandwidth is not enough, the amount of voltage can also be a way to
indirectly determine. Normal output of the CPU clock, voltage 0.3V or so.
There also need to test the north and south bridge clock
H_GTLREF here to take VCCP 2 / 3, is 0.7V. The CPU voltage is the definition of high and low points, commonly known as the false base mounted on the load voltage. Northbridge has a similar test points, as follows:
FSB bus resistance , whether Intel’s HOST, or AMD’s HT bus, FSB are no open-circuit system without the necessary conditions to go yard. Here you can use with light-load to measure, reduce the amount of manual labor to fight the resistance, with light load if there are some false light does not light, indicating that there are open to the North Bridge, if some light brighter than other lights, indicating that the data lines are short. Uncertain circumstances, it can be verified with a multimeter again.
HOST 界面和DMI 界面补偿电阻
These are precision resistors. Some designs may be unreasonable pressure to the top of the radiator, damage to the resistance, leading to not take the code. If the LPC moment any action, but did not last. You can look at the amount of LPC and PCI bus 33M resistance and the corresponding clock. Here the LPC bus, for example, if LAD0, 1,2,3, FRAME, which have too large a resistance or a few cases, the board may have broken. LPC devices may have a small short-circuit. In contrast, LPC bus, it is quite easy to go wrong.
Negative output power supply may also affect the CPU to the CPU’s normal to go yard. Although the CPU power supply has output, but the CPU is a high-speed devices, sensitive to external conditions, have the CPU power supply output is still necessary to look at the power supply waveform.
It should be clear that the majority take the FF machine, we could not measure the voltage on any surface and waveform abnormalities, the more new models more so. Many cases can only be tentative brush BIOS or change the bridge. General order for the bridge is Southbridge, Northbridge, CPU. In terms of models for Hublink architecture, PCI bus exception will lead to not go yard. If the bus between the Northbridge and Southbridge conditions have Hublink amount again. After DMI architecture models, there is no CPURST enough to reflect the DMI bus connections, no need to measure.
