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Nederlands Forum over Oude Radio's |
Re: Philips 834A repair advice required
Geschreven door Nico den Haak op 25. Jun 2005 11:52:00:
In reactie op: Re: Philips 834A repair advice required geschreven door Mike Horne op 23. Jun 2005 20:59:23:
Hello Mike,
Another thing: it's possible that the switch needs cleaning first. Also the pin needs to be an exact fit. If this doen't solve your problem, maybe you need to examen the value of the negative grid voltage on the first grids of L1 and L2. When you measure the value of the tension on the first grid of L1, also turn the volume control to check the good working of R1. The voltage must variate with it. I don't know the exact value's, must be somewhere between -10V and around 0V when you turn the knob i think.
The most important thing is that you have a good response when turning the "volume control" I trust you have already checked the anode and screen voltage values of all valve's? Don't forget the negative grid of L4, also check it's anode current. Because i find your value 320V of the HS a bit(to)high. Even when using a modern measuring equipment. When L4 has lost his emmision, the HS will go up, because L4 is taking up the most current from the supply.
High value resistors are always under suspect. Please check them thourough. If you have one with an o/c, you can always fit a Philips 0,5 watt sixties resistor inside it's housing. At the outside nobody will notice the difference.
Succes!
Best regards,
Nico den Haak.