Trouble Shooting - Kenwood TH-D72A Service Manual

Built-in GPS Operation Check Method
after Repairs
When the built-in GPS is turned ON, the main MCU sets
the IGPS_TXD as High level and requires the start of the
GPS data transmission to the built-in GPS. The location data
is sent to the main MCU via the IGPS_RXD.
The data of the built-in GPS, such as the latest satellite
information that is necessary for a hot start, is stored in the
battery backup memory (BBSRAM). The BBSRAM backup
power source is supplied by the backup power source input
terminal (GP_BU), separate from the main power source
input terminal (33GP) of the built-in GPS. If there is a normal
voltage external power supply input from a charged rear bat-
tery or through the DCin terminal, the BBSRAM of the built-
in GPS is backed up.
Even if the rear battery is removed or the external power
source is disconnected, the built-in GPS is backed up for ap-
proximately 3 minutes with the secondary internal lithium
battery (when the secondary internal lithium battery is at full
charge).
However, when the DC plug is connected to the DCin
terminal but with the external power supply turned off and
a rear battery is installed, the built-in GPS will not be backed
up beyond what is available by the secondary internal lithi-
um battery.
When the latest satellite information is backed up, the
built-in GPS is able to hot start. But, when the satellite in-
formation is not updated up for approximately 2 hours, the
built-in GPS is cold started.
■ Operation check method
1. Turn the transceiver power ON.
2. Switch to the GPS only mode by performing the follow-
ing operations:
[Menu] > GPS [ OK] > Int. GPS [ OK] > Operating
Mode [ OK] > GPS Only [ OK]
∗ Operate in the menu mode as follows:
Press the [ ] / [ ] keys to select an item.
Press the [ OK] key to set the content.
Press the [ESC ] key to return to the previous content.
Fig. 1 Menu screen 1

TROUBLE SHOOTING

[ OK]
TH-D72A/D72E
After pressing the [ OK] key, the initial screen of the
GPS Only mode is automatically displayed.
Fig. 2 GPS Only mode initial screen
3. Switch to the location data screen by operating the fol-
lowing keys.
• [POS]
After pressing the [POS] key, "Finding GPS satellites..."
is displayed when the position has not yet been calcu-
lated. Once the position is calculated, the latitude and
longitude is displayed. In this case, the built-in GPS is
connected properly.
Fig. 3 Satellite search screen
Fig. 4 Latitude/longitude display screen
If "iGPS ERROR" appears after a short while ("Finding
GPS satellites..." is not displayed), a communication er-
ror between the built-in GPS and the main MCU has oc-
curred.
Fig. 5 Built-in GPS communication error screen
Either the built-in GPS is not connected properly, or the
input/output circuit is malfunctioning.
When the position calculation is completed, and you
are in a location where the GPS satellite signal can be
received, the display changes from "Finding GPS satel-
lites..." to the latitude/longitude display.
The built-in GPS is operating normally if the position cal-
culation is completed.
37