C. 50 + 50 uF in B6CA38A (Techniek Radio/TV)

door soundman2 , Wouw, 28.04.2015, 11:54 (3500 dagen geleden) @ Pandu Rajan
Bewerkt door soundman2, 28.04.2015, 12:02

Dear Forum members

I have a radio gram which has the set B6CA38A made by Philips India. Recently it developed a hum problem. On investigation I found one of the 50ufd capacitor faulty. I measured the capacitance of both. The healthy one showed a value 47ufd whereas the faulty one showed a value 0.008ufd. So practically the value of the faulty part had nearly become zero. This resulted in increase of the AC reactance to a very high value causing the hum.I had a spare filter capacitor, though old one, but on measuring the capacitance I found the values as 67ufd/75ufd. If I use this capacitor what problem would it cause? I understand that if a higher value of the filter capacitor is used then the valve EZ80/EZ81 is more stressed. But a filter capacitor which is old and due to aging whose capacitance value has increased will also cause the same problem which a new capacitor of higher value would have caused? Is it possible to detect by performance vise whether the filter capacitor value has increased or not?

Regards

P.Rajan

A little rewiring solves your problem.
Connect te good half (47uF) direct to the rectifier tube as first capacitor (C25) and the new cap as second, the second is connected via a filtercoil (output transformer).
If the bad cap is already the second (C26), no rewiring is necessary.
Soundman2