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Re: Blue flash in an AX50
Geschreven door Frank Philipse om 22. Apr 2001 22:30:02:
In reactie op: Blue flash in an AX50 geschreven door Thierry Magis om 22. Apr 2001 20:52:46:
>Hello !
>A friend has give to me a lot of very old Philips amplifiers type 2844 , EL6420 , EL6435(searching diagrams of this model!). Some are in good condition , others quasi-totally destroyed . I try to repair all , i like their sound ...
>I've got a problem with an EL6420 : one of the two AX 50 "flash" when there is high power output. The blue light is very impressive - but i don't like it too much ! When i invert the two valves of the voltage multiplicator , the problem stays in the same valve. I first think at problem with the smoothing capacitors , but they seems to be OK ... Is this flashing normal? Does it increase with the age of the tube? I know the AX50 are gas-filled , is there a loss of this properties?
>Thank you very much !
>Greetings
>ThierryHello Thierry,
You can find the circuit diagram / service manual for the EL6420 here: http://frank.nostalgiaair.org/instruments.html
It is not normal to have flashovers inside the AX50. It is normal that it glows more when the amplifier has to deliver more power.
Maybe you should check the voltages in the amplifier. Very important is the negative voltage on grid 1 of the output tubes. See table at page 6 in the service manual (after downloading of course). It's also possible that the AX50 nears the end of it's life.
Very nice amplifier the EL6420! Wish I had one.
I have no info for the EL6435.
Maybe I have something for the 2844, I will try to find it. Is it the one with EE1 or EEP1?
If I find it, I will add it to my 'instruments' page.
Regards,
Frank