Philips 7538, Руководство по обслуживанию

Страница: 42 / 67

3. Move the meter probe to OSD test point, TP33 (E-2).
4. Adjust L325 (E-2) to achieve a voltage at TP33 that is equal to one half of the voltage recorded at TP32
(approximately 2.5Vdc). This voltage must be set within the following tolerances: -10% to +2% of half of the
voltage recorded at TP32.
Remote Locator RF Xmtr Out Adjustment
1. Short L301 (B-4) to Ground (the end closest to IC2 (A-4)). This turns the
Remote Locator on.
2.
Short Antenna Al to ground.
3.
Connect a 5OMHz. Oscilloscope to L6 (B-5), connect to the end closest
to IC2.
4.
Use a 100:1 scope probe or a probe with a very high input impedance to
avoid loading the signal.
5.
Adjust L9 (B-4) to achieve the maximum signal level on the oscilloscope (if a 100:1 probe is used be sure to set
the scope to read a very low voltage).
Clock Calibration
Note.- Clock models are shipped from the factory with a default value of 00 or 80 for NO correction. When
setting the correction avoid 00, 64 or 80 when a -1 microprocessor is being used If correction is necessary use
the following procedure:
1. Minutes of error per month X2 = Seconds of error per day
2. Determine if the clock is gaining or losing time
3. Enter the Service Mode and access register 84 via the numeric keypad on the remote transmitter. If the value
is 00 or 80 refer to the use table for the number of seconds of correction needed, fast or slow, and enter the
calibration code (hex).
EXAMPLE:
4 minutes fast a month X 2 = 8 seconds a day fast. The chart says if the clock is 8 seconds a day fast without
correction use 59. Change register 84 from 00 or 80 to 59. If there is a calibration code in register 84 other than
00 or 80 see the following examples:
COMPLEX EXAMPLE #1:
Using the error from the previous example, 8 seconds fast a day, go to register 84 and see that it has a value of
16 already in it. Look up 16 on the table and find that there is already a correction for 2 seconds fast a day. 8
seconds faster is needed (2 + 8 = 10) or a total of 10 seconds fast correction which is 6E. Enter 6E in register 84.
COMPLEX EXAMPLE #2:
If the clock is 8 seconds fast a day and 96 is already in register 84, a 2 second a day correction in the wrong
direction (slow) is present. The code for 6 seconds fast should be loaded (43 from chart), this adds up to 8
seconds fast correction.
IF CLOCK IS FAST:
Freq.,Hz.
Cal.
[-Comp.] (Hex) (sec./day)