Rf Agc Adjustment; Vif Detector Output Level Confirmation; Buzzing Confirmation (Audio Circuit); Anode And Heater Voltage Confirmation - Panasonic TC-21FX30LA Service Manual

ADJUSTMENTS
ITEM / PREPARATION

1- RF AGC ADJUSTMENT

1. Supply a color bar PHILIPS pattern and adjust the RF
input signal of 69 dB mV (75W opened channel 7 RF
freq.: 175.25 MHz).
2. Connect the digital multimeter in TPA15.
2- VIF DETECTOR OUTPUT LEVEL CONFIRMATION CONFIRMATION:

BUZZING CONFIRMATION (AUDIO CIRCUIT)

3-
1. Connect the oscilloscope with a 7KHz filter between A22-
2 and A22-3 speakers terminals .
Set the controls as follows:
Volume ................Maximum
Balance ............. Center
Surround ............ OFF
Hyper Bass ........ OFF
AVL ...................... OFF
Sound Menu ...... Dialog

4- ANODE AND HEATER VOLTAGE CONFIRMATION

1. Supply a crosshatch signal.
2. Adjust the current beam to zero. (0 beam).
3. Adjust "SCREEN VR" and "CONTRAST" to minimum.
Note:
(When using a high voltage meter resistive type, it is
necessary to use an electrostatic meter type to verify the
values)
PROCEDURE
ADJUSTMENT:
1. Select "RF AGC" on "CHK2" service mode.
2. Adjust "RF AGC" by pressing VOL(+) or (-) until obtaining
2.2±0.1V in TPA15.
3. Increase the input level by +2 dB and confirm that the
voltage decreases in TPA15.
1. Install the chassis in the VIF calibration JIG and tune in a
63 dBU colorbar pattern (75Ω opened).
2. Connect the oscilloscope in TPA31.
3. Confirm that the output video sign is 1.05 ± 0.15 Vp-p in
TPA 31.
CONFIRMATION
:
1. Supply a colorbar signal with local frequency adjusted
and the AFC ON (Channel with sound bearer and without
modulation).
2. Assure that the width in the buzzing waveform is smaller
than 500 m Vp-p.
CONFIRMATION
1. Connect a voltage meter between TPA10 and ground.
Confirm that the voltage +B is within a range of 140.5V±
1.5V
2. Connect a high frequency voltage meter (VRMS) among
the heater, and confirm that the voltage is according to
the table below:
21"
29" Flat
3. Connect the high voltage meter in the CRT anode pin,
and confirm that the high voltage is be among 25,2~23KV
for 14" CRT and 27,2~25KV for 20" CRT .
- 23 -
TC-21FX30LA/LP / TC-29FX30LA/LP
smaller than
500 m Vp-p
6,30 ± 0,25 Vrms
6,30 ± 0,25 Vrms