NXR-810
55
TROUBLE SHOOTING
1. Fault Diagnosis of the BGA (Ball Grid Array) IC
■
Overview
A
fl owchart for determining whether or not the transceiver can be powered on (
the Display does not function even if the
power switch is turned on
) due to broken BGA parts.
■
BGA parts
ASIC (IC20), DSP (IC6), SRAM (IC9)
●
Checking power supply voltage
Checking voltage
Points to be checked
Normal voltage
33M IC303 (5 pin)
3.3V
16M IC305 (5 pin)
1.6V
15M IC304 (5 pin)
1.5V
33A IC306 (5 pin)
3.3V
33BU Q303 (Collector Side)
3.3V
Power supply of each device is connected through the coil.
[ASIC]
33M: L20 and L308, 15M: L309
[DSP]
33M: L4 and L308, 16M: R324
[SRAM]
33BU: L5
●
Checking the clock
Checking the frequency and the magnitude voltage
Points to be checked
Normal Freq. and Magnitude
18.432MHz R115 (ASIC side)
18.432MHz 3.3V
R52 (DSP side)
18.432MHz 3.3V
32.768kHz IC17 (1 pin)
32.768kHz 3.3V
When a normal
value is confirmed.
When a normal
value is confirmed.
●
Checking the Reset/Control signal
Checking the reset and control signal input to the ASIC
Points to be checked
Normal voltage
RESET R511
3.3V
/BINT IC307 (1 pin)
3.3V
/OVRB Q301 (Collector side)
3.3V
Checking the ASIC input switch signal
*Each signal is not masked by the setting of the FPU.
The POWER key is pressed and held.
Points to be checked
Confirmed voltage
/PSW R271 (ASIC Side)
0V
[18.432MHz]
Remove the R115 and R52. If it oscillates normally,
the DSP and ASIC may be broken.
[32.768kHz]
Exchange IC17(RTC). If it oscillates normally,
the ASIC may be broken.
The BGA parts are not broken.
Checking for an abnormal point
33M has an abnormal voltage.
[ASIC]
Remove L20 to check the voltage of the 33M.
If the voltage becomes normal, the ASIC is broken.
[DSP]
Remove L4 to check the voltage of the 33M.
If the voltage becomes normal, the DSP is broken.
16M has an abnormal voltage.
[DSP]
Remove R324 to check the voltage of the 16M.
If the voltage becomes normal, the DSP is broken.
15M has an abnormal voltage.
[ASIC]
Remove L309 to check the voltage of the 15M.
If the voltage becomes normal, the ASIC is broken.
33A has an abnormal voltage.
[ASIC]
Remove L316 to check the voltage of the 33A.
If the voltage becomes normal, the ASIC is broken.
33BU has an abnormal voltage.
[SRAM]
Remove L5 to check the voltage of the 33BU.
If the voltage becomes normal, the SRAM is broken.
If the voltage is not corrected, there is a problem
other than the BGA parts.
When an abnormal
value is confirmed.
When an abnormal
value is confirmed.
When an abnormal
value is confirmed.
●
Checking the output signal
from the ASIC
Points to be checked
Normal voltage
/FRST IC3 (12 pin)
3.3V
If the /FRST is always 0V, the ASIC is broken.
When an abnormal
value is confirmed.
When an abnormal
value is confirmed.
When a normal
value is confirmed.
When a normal
value is confirmed.
When a normal
value is confirmed.
