|
QUESTION NO. P102902-4: Panasonic Panasync S110 monitor Chassis HV10S has no display. B+ is normal, Yoke drive OK. No drive to flyback and no output from IC671. |
Review Question number P60602-5. Also check J114 which on this model may be 800mA microfuse or as the S110i has Q861 is the same thing on the 185V rail. Check Q881, Q549 & R890 also review Question P311-4. |
The flyback transformer (TLFA01365) is very high failure in this chassis. Check out the flyback's internal capacitors, from the HV anode to pin 14, and to pin 15. If the capacitor to pin 15, that gives HV feedback for IC671, goes leaky/shorted, the output from IC671 can become reduced, to very narrow spikes, or shut off. Also check if IC671 is now bad. |
QUESTION NO. P101102-7: Panasonic Panasync S110i Chassis 21HV12S Model TX-D1F64MA monitor. Has vertical white line signal ok, yoke ok came in with shorted h/def transistor Q555 (2SC5423), used 2SC5047 problem remains. Have reviewed questions P311-4, P61402-7 & P60602-5, very similar in most cases but not exactly the same. Secondary voltages ok. Suspecting D606 Sanken RP1HN special build reads high impedance, is this correct or going in wrong direction? Q881, Q549 & R890 are also ok. |
Beware of false board numbering. Q861 is not a transistor but an 800mA semi-fuse, after replacing this the 185 volt rail was restored and works fine with 2SC5047 a little bigger physically but angle the 6.8 ohm resistor to fit. |
A Sanken RP1H is a 2KV diode, and its forward voltage is 6 to 7 volts, so many meters will read it as open-circuit in the forward direction. First, check the P/S secondary, on the 185 Volt supply, and see if either R861 (0.33 Ohm, 1/2W), or the microfuse at location Q861 (TO-92 case, UN11008 = 0.8 Amp fuse), are open. If the 185 Volts gets to Q881, after all, see if Q881 has gate drive. If no, check IC850. If Q881 is getting gate drive, and providing B+ voltage to the collector of Q555, after all, see if Q555's base has horizontal drive from IC580, via Q549; also check R554, D555. |
QUESTION NO. P90302-8: The image size of Tektronix TX-D1F63R monitor (Chassis Panasonic 21HV10S) is too big to fit screen as a sudden event. An adjustment via OCD is not possible (range too small). Image is relatively sharp and clear at slightly decreased brightness. |
You should be looking for a coil that has changed in value, or the center core has dropped to the bottom of of the coil. |
QUESTION NO. P61402-7: Panasonic PL-70 monitor has no horizontal deflection. Measuring Q550 gives nice waveform on oscilloscope. Bringing up brightness shows vertical line 4 mm wide. I am using P-70 schematic as it seems similar. R588 & R589 are ok. |
Found the deflection problem. 1st problem was scope, measurement probe was partially broken, ( ground connector not connected sometimes) thus I had false measurements. The real problem was J114 was open, this is actually miniature fuse, rating unknown, maybe 1A. The reason for fuse blowing was Q881, 2SJ306 was shorted. |
QUESTION NO. P60602-5: Panasonic panasync S110 monitor chassis HV10S. The lower part of the picture has become a very dense line in the middle of the crt and there is nothing in the lower part of the crt. R482 (150ohm) has overheated beyond identification. |
Your R482 and R483 should have matching values (other models use 1.2 ohm, 1 Watt), so compare R482 to the value of R483. Check if R482 burned due to an overload from a shorted component off the vertical IC, LA7875, including the filter cap off of pin 2, and check the vertical IC, itself, as well. |
QUESTION NO. P311-4: Panasonic Panasync S110 monitor. The HOT 2SC5423 and transistor Q881 2SJ306 were shorted. I changed them and now I have the HV but there's a single vertical line at the screen, probably the horizontal deflection. I checked for bad solders or components but everything seems to be fine. I checked the yoke coil with an ohmmeter and that's fine too. Could it be the horizontal deflection transformer? With an ohmmeter, all the pin on the primary have low resistance between them, same for the secondary. |
Q550 is only for horizontal deflection. Check if its B+ resistor, R890 = 1 ohm, has also opened up. Aside from the B+ resistor, there should be DC continuity between the drain of Q881 and the collector of Q550, through the inductors. If this is OK, check if Q549 and IC580 are good, and providing drive for Q550. Also check the associated electrolytic caps, C551, C578, C859, etc. |
QUESTION NO. P1114-5: Panasonic S50i TX-T5F73 monitor is dead. On main power supply board, R803 SCK162 is broken. |
SCK162 is an inrush-current limiter, rated for 2 Amps, and initial resistance of 16 ohms at 25캜. A Keystone Thermometrics' CL170 device should substitute; Mouser Electronics (www.mouser.com) lists CL170. This monitor may have taken a surge on the AC power line, or had a short in the primary. I would check main cap C820, bridge diodes D801-D804, line filter L801/L802, fuses F801, F802, F804, F805, and FET Q820. If Q820 had shorted, check components off its gate, including IC820, and ring T801. |
QUESTION NO. P921-4: Micron 700FGx monitor. Looking for correct value & voltage on the ceramic capacitor C556, in chassis #HV9. |
In the Panasonic 17HV9 chassis, C556 is 470 pF, 2KV. |