[mechanical model]: hs525td
[board number] hs-525t chip group type d525 cpu+nm10 south bridge
[facilitation]: the cashier's main panel is not powered to display
Maintenance:
The customer sent a cashier computer, which was described as unable to turn on and tested the machine to confirm that the main plate was unresponsive. First, there's a collection computer and a master board。
The first step was to cut the main plate, measuring positive 12 v, plus 5 v, plus 3. 3 v on the main panel with a mass gauge, the primary memory supply of 1. 5 v, the bridge core supply of 1. 5 v and 1. 05 v, and the unaccepted cpu vore supply barrier。
In the second step, the eight waiting conditions at the south bridge can only be checked by chip group time. The time chart is as follows:
An analysis of the physical time chart of the master plate indicates that it would be useful to check the protection of the main board, i. E. Dc12v, and to hit the ground value first. The first foot of the tensile meter pq6 mos tube has 12v voltage, but the eighth foot is zero voltage. The diagrams are as follows:
This tube is the mos tube of the p-tunnel, which, when the four feet are low, the 1/8 foot of the mos is fully connected and the g is controlled by pq97002 mos. The 12v voltage was distributed to the pq9 g pole by approximately 1. 0 v voltage via pr20 20k, and the 7002 tube conductor was used to split the control signal resistance between pr17 and pr19 on pq6 so that the 8th foot of pq6 had 12v voltage output. The process was performed using oscilloscopes to measure the pq9 tube at foot 1 voltage of 0v, which is normal for 1v. After the main plate was cut off, the visual look of pq9 and the surrounding components was examined, and the prc20 was found to be impervious, and after finding a 20k resistance from the material box, the main plate was placed on tester pq6 foot 8 + v12al voltage ok, which triggered the key opening of the main plate, and the main plate was still without a sound, which took me half an hour。
Step 3, check +v5sb and +3. 3s for south bridge, with main plate number pu2 uz1085l。
Standby voltage is 0k:
Step 4, check the rtc part of the south bridge and the working conditions. As shown in the figure:
Checking the 3rd foot 3. 3v vccrtc of the d4 bat54c diode with a oscilloscope and checking the 2nd rtcrst# 3. 3v signal on jcmos cap is ok。
The oscilloscope measure y32, 768khz crystal waveform is normal。
Step 5 examined the south bridge standby voltage with the pm-rsmrst signal, and the oscillator measured 3. 3 v at a position of su1 74hct14 circuit。
The master plate has the physical upper number r233。
Step 6, overhauling the pansw signal to sio it8718f and to the pwrbtn signal on the nm10 south bridge. As shown in the figure:
The 75th foot on it8718f, the 72nd foot and the 71st foot were checked for high- and low-level electrical flat-jumping processes。
The sio chip received the slp s3# signal, which would lower the ps on signal from the 76th foot, so that the master plate would complete the powering. The oscilloscope checked the 76 foot signal for a pull from 5v to 0v and followed the signal back to the pq12 mos tube。
The rationale analysis is as follows: pq12 foot 1 is the end of a low-altitude tube, and +v12al voltage is blocked to the first foot of pq11. 702 n via pr21,100 k, which enables mos tube conductorization, resulting in a split pressure of p18 and pr22, lowering the g pole of the pq8 ap6679gm p ditch channel, and generating +v12s working voltage from the d-s polar channel。
The 1st foot of the pq117002 tube was measured at 0v voltage, and the main plate was hit with a g-to-ground value of 20 euros after another power outage of the pq11 tube, with suspected resistance values abnormal。
As a result, the pq11 mos tube was opened with a barbed iron and the ground value of the first foot recovered to 500 om. It appears that the small mos hose was damaged, the 7002 tube was loaded from the scrapboard and the main plate was activated and the electricity went back to normal. I'm glad the backboards didn't turn on, when i saw the lunchtime and left the machine for dinner。
Step 7 main board is not open, following the three principles of electronics work, to check the power supply clock and re-entry signals. The pltrst signal on the oscilloscope card chip is 0v. The original master plate was not reset and the signal was normal for 400 euros. Checked the main plate, all the power was normal, and in order to make quick decisions, the main plate was replaced by the south bridge, and the sound of the bells remained。
Step 8 can only recheck the clock signals of the south bridge, mainly pci 33m clk and pcie 100m clk。
The waveform and face-to-ground resistance of the 46/47 foot on the measured clock chip. The pci clk 33m wave shape on foot 7 of the check clock, followed to point a on r8 22, but point b on the block was zero-v-free, and r8 was found to be inexhaustible, and it was also electrically induced by a mass gauge. By this time, the main panel was repaired and the main panel was installed in the case。
The two-hour machine repair process took me three hours to write a sticker, which seems to be more difficult than a fixer。
