SERVICE PROCEDURES
HT-R820THX
1. Replacing the fuses
This symbol located near the fuse indicates that the
fuse used is show operating type, For continued protection against
fire hazard, replace with same type fuse, For fuse rating, refer to
the marking adjacent to the symbol.
Ce symbole indique que le fusible utilise est e lent.
Pour une protection permanente, n'utiliser que des fusibles de meme
type. Ce demier est indique la qu le present symbol est apposre.
3. To initialize the unit
This device employs a microprocessor to perform various
functions and operations. If interference generated by an external
power supply, radio wave, or other electrical sauce results in accident
which causes the specified operations and functions to operate
abnormally.
To perform a result, please follow the procedure below.
1. Press and the hold down the VIDEO 1 button, then press the
STANDBY/ON button when the unit is Power On.
2. After "Clear " is displayed, the preset memory and each mode
stored in the memory, are initialized and will return to the
factory settings.
REF NO.
PART NO.
DESCRIPTION
F6901, F6902
F6901, F6902
F6901 or, F6902 or
F901
F901 or
F903
F903 or
252199
252100
252307
252198
252261
252164
252258
10A-UL
10A-EAK
10A-TL250V
8A-UL
8A-T/UL-ST2
5A-UL/T-237
5A-T/UL-ST2
2. Safety-check out
After correcting the original service problem perform the
following safety check before releasing the set to the customer
Connect the insulating-resistance tester between the plug of
power supply cord and terminal GND on the back panel.
Specifications: More than 10Mohm at 500V
The HT-R820THX uses a battery-less memory backup
system in order to retain radio presets and other settings
when it's unplugged or in the case of a power failure.
Although no batteries are required, the HT-R820THX
must be plugged into an AC outlet in order to charge the
backup system.
Once it has been charged, the HT-R820THX will retain
the settings for several weeks, although this depends on
the environment and will be shorter in humid climates.
5. Memory backup
REMARKS
<Note>
Main microprocessor Q7008 only.
1. Press and the hold down the DISPLAY button , then press the
STANDBY/ON button when the unit is Power ON.
Version is displayed on FL display only for 3 seconds.
2. Press the STANDBY/ON button to Power Off.
4. To check version of microprocessor
Ver. 075 (04809a)
<ex.>
NCDG-8230
25138230B
GND
232RXD
232TXD
NC
FVCC
P7701
Q7008
Main microprocessor
6. Changing the AM band step
1. Necessary to change as follows.
R7003
Change to 10 kohms. Refer to <Fig-1>
R7004
Change to 10 kohms. Refer to <Fig-1>
2. To select.
Press and hold down the TUNER button , then press the
MEMORY button.
Component side
<Fig-1>
NADG-8230 (Pre-amplifier PC board)
R7004
R7003