Asus P526, Service Manual

Page: 40 / 113

GTC
■
Service Manual
GP137_TMC_EN)
f. Pin#4 (IN1) and pin#8 (IN2) of U29 is high (connected to GP137_TMC_EN) and pin#3
(COM1, DOCK_PIN2) is switched to pin#2 (NO1, MPU_RX1_3V3) and pin#9 (COM2,
DOCK_PIN3) is switched to pin#10 (NO2, MPU_TX1_3V3), that meaning L27 and L28
shall have correct signal (high –> 3.3V, low –> 0V) if TMC is working.
g. R245 (GP139_DOCK_PIN#4) shall be around 2.8V, when TMC cable is inserted. It is the
indication that TMC cable is inserted.
5.13 USB connection
(active sync.)
Needed Equipments:
A. Battery of P526.
B. Oscilloscope
C. Mini USB cable
D. PC
a. USB connection (for active sync.) uses same connector with TMC cable. Both signals R245
(GP139_DOCK_PIN#4) and T59 (GP137_TMC_EN) determine which device will be
selected. The combination is listed below.
In USB mode: R245 is low (0V) and T59 is low (0V).
In TMC mode: R245 is high (2.8V) and T59 is high (2.8V).
b.
Pin#2 of R126 (USB_PU_EN) shall be 3.3V.
c. T59 (GP137_TMC_EN) shall be low (0V) and U29 shall be switched to NC1/2 (USB_R_D-
and ).
d. L27 and L28 shall have correct signal (high –> 3.3V, low –> 0V).