Siera CTS-AA, Руководство по обслуживанию

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8.3 AFC
IF Carrier frequency can be adjusted in automatic or manual way. It is recommended the automatic way.
There is an adjusting symbol for AFC on the top of the service menu consisting of a double arrow (><). If only one arrow
appears (<) or (>) AFC should be readjusted to reach double arrow (><).
8.3.1 Automatic AFC adjustment
- Insert a 38.9MHz 106dB/µV signal in pin11 of the tuner (1001 diagram C) across the following network:
Note: For Pal I sets, frequency is 38.9MHz only if saw filter (1015 diagram A) used is J1952.
If saw filter is J1951 frequency of the inserted signal should be 39.5MHz.
- Select AFC Adjust (item 23 of Service menu) and press V+ on RC.
- Press OSD key to save adjustment.
- Enter in Service menu again and check that adjusting symbol is correct (><). If not, readjust AFC Fine (item 2 of
Service menu) till symbol is (><).
Multistandard sets
A second adjustment for L’ system is necessary when the set is multistandard, to do it TV should be tuned in
the first half of BI (L’ channel).
- Repeat the same automatic AFC adjustment procedure, inserting a signal of 33.9MHz instead of 38.9MHz
and using AFC LP Adj. (item 24 of Service menu) and AFC Fine LP (item 4 of Service menu).
8.3.2 Manual AFC adjustment:
- Insert the frequency signal defined in 8.3.1
- Adjust the value of AFC coarse (item 1 of Service menu) to 00 and the item value of AFC fine (item of Service menu)
to 40.
- Increase the AFC coarse value just till adjusting symbol is (><) or (<) and adjust AFC Fine to fine a value just in the
middle of the range fulfilling the correct symbol (><).
Multistandard sets
TV should be tuned in the first half of BI (L’ channel)
- Repeat the AFC Manual AFC adjustment procedure inserting a signal of 33.9MHz instead of 38.9MHz and using
AFC coarse LP (item 3 of Service menu) and AFC fine LP (item 4 of Service menu).
8.4 AGC Adjustment
- Connect a pattern generator to the aerial input with RF signal amplitude = 1mV.
- Adjust the value of AGC start (item 6 of Service menu) so that voltage at pin 1 of the Tuner (1001) is 3.7V.
8.5 White D
8.5.1 Manual cut-off:
Item 8 of adjusting values should be 00 (see table 8.1), that means set is in automatic cut-off. However it is possible
that RGB do not start (black picture), due to grid 2 is not adjusted. In this case we recommend to change to Manual
cut-off ( Item 8 = 01), pre-adjust grid 2 to have a good picture and change to automatic cut-off ( Item 8 = 0) before
continue adjusting (see warm-up detection circuit in 7.1.5)
8.5.2 Grid 2:
- Connect a white pattern generator.
- Adjust contrast at 07 and brightness at 22.
- Adjust VG2 potentiometer ( in line transformer ) till voltage in collector of transistor 7213 is 142V in 20"/21" or
134V in 14" (measured with a DC voltmeter).