Philips PTV2

HOW TO ENTER SERVICE MODE TO PHILIPS [PTV SERES] TVs

PHILIPS; PTV800_PTV805_PTV810_PTV811_PTV815_PTV820_PTV825 _ SERVICE ADJUSTMENTS.
                                                                     PART -1

• All service adjustment to this chassis are hot voltage wise, So ensure the use of properly insulated tools.

TUNER ADJUSTMENT

• Turn the set ON, and tune to an on-air station.
• Connect digital voltmeter to [TP-41] on the small signal panel.
• Adjust (C341) [Zone E-6] to obtain a reading of 2.5VDC on the meter.
• This adjustment may effect on-screen menu positioning  as well as other graphics generated set.

RF AGC DELAY

• Single tuner models. [ASG051 & ASG052]. The adjustment control [R202] can be located on the small signal panel in zone area J2.

1. Tune to a weak station.
2. Set R202 to its fully counterclockwise position.
3. Slowly advance it to a point slightly beyond the point of minimum noise in picture.

• Two tuner models. [ASG053 & ASG054]. Control resistor [R256] can be located on the small signal panel zone area K5  Use the adjustment procedure as described above, to this adjustment too.
• Do not advance the control any further, as it may result in an overloaded picture.  The range of the AGC voltage supplied to pin [9] of the Varactor tuner may vary from 4.2VDC without signal, and 1.87VDC with signal.

VCO AND AFT ADJUSTMENT.

Single tuner models.

1. Cut the shield break point around IC200, and the IF circuitry.  Peel the top cover of the shield to gain access to internal circuitry.
2. Short test points 16A&16B of the varactor tuner module.
3. Short test point [23] to ground.
4. Connect DC voltmeter to test point [7].
5. Turn the set ON, and record the voltage reading from test point [7].  Typically 4.5V to 5.0VDC.
6. Turn OFF the set, and remove both shorts from test points TP16A/B and TP23.
7. Connect the coincidence line at the collector of [Q207] to +5V DC line on the tuner.
8.  Apply local broadcast signal, preferably on-air signal, to antenna terminals and turn the set ON.
9. Select the cable tuning from the menu item, select channel 36 or other high band inactive cable channel.
10. While still in cable mode, select local VHF broadcast channel.  The tuning system will attempt to tune three times and then lock on to the FCC assigned frequency.
11. Adjust AFT coil [L202] to obtain a reading of +7.5VDC at test point [tp2].
12. Adjust VCO coil [L204] to obtain the same DC voltage that was noted above.
13. Remove the jumper wire from coincidence line.
14. Verify the adjustment by changing between by High Band and local VHF broadcast channel, and ensure that the local broadcast channels lock in quickly.

Two tuner models.

1. Cut the shield break points around IC201 and IF circuitry.  Peel back the top cover of the shield to gain access to the internal circuitry.
2. Short test points [16C&D] of the varactor tuner module .
3. Short test point [23A], pin 13 of IC201, to ground..
4. Connect DC voltmeter to test point [7A].
5. Turn the set ON and record the voltage reading from test point [7A]; typically 4.5 to 5.0VDC.
6. Turn OFF the set and remove shorts from test points [TP16C,D&23A].
7. Connect the coincidence line at the collector of Q207, to 5VDC line on the tuner.
8. Apply local broadcast signal by the antenna terminal, and turn ON the set.
9. Select the Cable Tuning from menu options,and select channes 36 or some other high band inactive cable channel.
10. While still in cable mode, select local VHF broadcast channel. The tuning system will attempt to tune three times, and then lock on to the FCC assigned frequency.
11. Adjust the AFT coil [L219] to obtain a reading of +6.6VDC, at test point [TP2A].
12. Adjust the VCO coil [L220] to obtain the same DC voltage reading at test point [TP7A] that was noted in step 5 of this adjustment procedure.
13. Remove the jumper from the coincidence line.
14. Verify this adjustment by changing between the high-band and local VHF broadcast channel and ensure that local broadcast channels locks in quickly.

Continued in part-2