Yamaha DRX-2 Service Manual page 96

DRX-2
1.3 Attenuating the 40.4 MHz [5710]:
(SECAM only)
Service tasks after replacement of coil 5710:
Purpose: To attenuate the band I carrier rests.
Symptom, if incorrectly set:
Bad picture quality when the filter attenuates the picture
carrier (38.9MHz).
TP ADJ.
OFW 1701 L5710
Pin 1
(F709)
DISC
If the adjustment is correct the signal at pin 1 of OFW
[1701] must be smaller than the input signal amplitude by
at least 6 dB.
2 Reprogramming Procedure of NVM on
the Microprocessor Sub PCB
The NVM, item 7808, on the Microprocessor Sub board
contains the following factory settings:
1. Clock correction factor
2. AFC reference value
3. Slash version
The settings 1,2 and 3 are stored in the NVM during the
production of the analogue board.
The slash version is stored at the end of the production
line of the set.
In case of failure, the NVM must be replaced by an empty
device. By way of commands via the Diagnostic Software
or via ComPair, the factory settings must be restored in
the NVM.
2.1 Clock Correction Adjustment
To guarantee an exact function of the real time clock, an
adjustment of the clock frequency is possible. The
adjustment value is storedin the NVM.
Procedure:
• put the set in service command mode
• execute command 1117 to initiate that a signal with
32768 Hz is available on pin 3 of connector 1988
DS:>1117
• measure the frequency f means of the Clock Crystal
with an accuracy of ± 0.1 Hz.
96
MODE INPUT
40.4 MHz,
TUNER
200mV rms at
Tuner 1705,
Pin 11 (F710,
IF-out)
MEAS.EQ. SPEC.
Oscilloscope, adjust
Sinus minimum
Generator, amplitude
Counter
• Calculate the parameter to be entered: 32768/f means
*10 6
• Normally the parameter must be between 999902 and
1000097. If the parameter and therefore the frequency
of the crystal is outside this range, the crystal must be
replaced.
• Execute command 1118 with the parameter as input
Example:
DS:>1118 1000023
2.2 AFC Reference Voltage Tuner
This function stores the reference voltage for the tuner in
the NVM. Before this value can be stored, the AFC
adjustment, described in the adjustment instructions of the
analogue board, must be carried out.
Procedure:
• Adjust AFC circuit
• Calculate the reference value
• Execute command 1119 and use the calculated
reference value as parameter
Example:
DS:>1119 128
2.3 Slash Version
The slashversion is stored with command 1217 followed
by the slash version as parameter.
The slash versions used are the following:
U model: 178
A model: 97
G model: 57
Example:
DS:>1217 57
Reset of Slash Version
Use command 1115 to reset the analogue board to the
default setting.
Procedure:
• Put the set in DSW command mode
• Execute command 1115 with the following parameters:
DS:> 1115 w 0xAE 2 0xD0 0x00
• Leave the DSW command mode and start up the set in
application mode
No background is visible on the TV screen. The
analogue board is ready to accept the appropriate slash
version