problemen Philips BX798X-02 : oplossing? (Algemeen)

door Pandu Rajan , 19.01.2016, 11:45 (3233 dagen geleden) @ Sieme

Dear Mr. Sieme
Thanks to all for the reply. I carried out further checking as follows:

1. I removed valve B8 and checked for any leakage at the terminals 6 and 7. But no leakage observed.
2. Considered the changing of the base for B8 valve as a last option.
3. The wiring to the k,g3 for both the valves B8 and B9 has been done as follows. A wire is connected to the terminal no 7 - k,g3 to the spigot of the valve holder of B8. From the spigot one wire goes to C102 and the other wire goes to pin no 7 of B9 which is again connected to the spigot of B9. R68 is connected from this spigot of B9 base to ground.
4. I suspected leakage voltage from the pin 5-g2 of the valve B8. I did not suspect leakage from pin 5 to pin 7 as it is at a good distance. I suspected a leakage from pin 5 to the spigot of B8 as both are very close.
5. I removed the wire from the spigot of B8 and directly connected pin no 7 of B8 to pin no 7 of B9 thus isolating the spigot of B8 and avoiding any leakage.
6. Now there is no Hum and all the voltages are O.K.
7.The final voltages are as follows.
a. At C1 - 301V
b. C2 - 290V
c. C99- 244V
d. C98- 211V
e.Valve B9 pin 2- 294V
pin 5- 290V
pin 6- -7.83V with respect to Cathode.
pin 7- 8.54V
f.Valve B8 pin 2- 295V
pin 5- 291V
pin 6- -7.95V with respect to Cathode
pin 7- 8.62V

Regards
P.Rajan