Sony MHC-6800 - Service Notes; Service Mode Operations; Service Position

SECTION 2
SERVICE NOTES
2-1, SERVICE MODE
When the test lands on the panel board are shorted, this set
will enter the Test Mode. This allows you to test the fluores-
cent indicator tube and the LED display and to turn power
ON/OFF.
Short these two lands with tweezers, etc.
3% The Test Mode cannot be entered unless the POWER is
turned ON.
(1) POWER ON
In this set, the control (AU BUS) of the power amplifier
TA-H6800N is used to turn the power ON/OFF. Without
this power amplifier, even if 100Vac is input, the set will be
always in the STANDBY (POWER OFF) state and any test
other than clock operation check cannot be performed.
Also, any power supply to the AUDIO system (A+10V,
DSP+5V) is OFF and so any energization check by sound
input is not allowed. Therefore, the POWER ON test lands
should be used to turn the power ON before entering repair.
(2) POWER OFF
This changes from POWER ON to STANDBY state. The
fluorescent indicator tube display will be of half brightness
to display the clock.
(3) TEST MODE
In the POWER ON state, when the Test Mode lands are
shorted once:
@ All LED indicators are totally lit. (VIDEO 1 and VIDEO
2/MD/DAT are lit orange due to simultaneous illumina-
tion of red and green.)
@ One vertical line appears on the fluorescent indicator
tube surface and moves from left to right. At this time,
make sure that this vertical line is not partially thicker.
{
|| =>
@® The fluorescent indicator tube display is totally lit and
this operation is stopped. Make sure that the display is
illuminating equally without unevenness.
Each time the Test Mode land are shorted, the following
operations are performed in turn:
Dolby sound in DSP menu is selected and
@ The parametric equalizer is set to 3dB up at 1kHz.
@® The parametric equalizer is set to 6dB up at 1kHz.
© The set returns to the STANDBY state and the clock
displays “0: 00” (Cold Start). All the parameters includ-
ing clock will be reset.
2-2. SERVICE POSITION
For this set, with the front and rear panels open, remove 4
screws securing the power transformer and 1 screw securing
the AC inlet. Then, by facing the power transformer down as
shown below, all the boards can be repaired.
MONITOR board
POWER board
| | INLET board
DSP board
MICOM board