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Old 1st Jul 2009, 2:47 pm   #61
Steve_P
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Default Re: Ekco U29

Not necessarily as it is basically an open circuit. When it gets some work to do, it plays up.

If it's not the valve (somebody give him one to try or he could try http://www.crowthornetubes.com/valcont.htm ), then if the caps are OK, I hope T1 hasn't gone faulty

Cheers,

Steve P.
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Old 1st Jul 2009, 2:56 pm   #62
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Default Re: Ekco U29

Ok just tried the other test . DMM on ma setting and tested between pin8 and c29(8uf cap)L15.The reading I got was 0.03-4 ma......
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Old 1st Jul 2009, 5:30 pm   #63
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Default Re: Ekco U29

Hi Ben, can I just clarify your last reading, I'm hoping you mean 0.03-0.04 A, ie 30-40 ma which strongly suggests that nothing in the HT line is amiss. ( and concurs with your earlier voltage reading across the choke )
Assume this is with the lamp limiter out ?

This is looking like a CY31 playing up under load possibly through an h-k short. Can't immediately think of anything else given these current and voltage readings.

I don't think this is an expensive valve anyway.

As per the earlier suggestion, you could now try a resistor/diode combination in place of the CY31, but ensure that there are no connections left to pins 5 and 8
The connection from R18 which went to pin 5 should go to the additional surge resistor, say 100 ohms, and the other end of this resistor to the diode anode. The diode cathode goes to the junction of C29/L15 ( trader sheet ). If this works without a problem, it may be worth leaving the valve in situ and making the diode permanent. You might need to further adjust the surge resistor to bring the HT line down to the correct voltage, as the drop across a silicon diode is a lot less !!

Andy
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Old 1st Jul 2009, 6:33 pm   #64
benjamin77
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Default Re: Ekco U29

Hi steve
Yes sorry I believe that you are correct about what I meant and what I actually wrote. With my limited knowledge I think its most probably the CY31 playing up when its under load also confirmed by when I switch out the lamp limiter F1 "pop's". I am not to confident it going down the resistor diode route.......

Think I will send the valve for testing...!
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Old 1st Jul 2009, 6:45 pm   #65
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Default Re: Ekco U29

I don't like valve testing, as a valve that is OK on a tester might not work well in a radio. And the other way round too by the way.

Get a replacement valve. If you don't need it, you've got it as a spare anyway. But I think you will.

Cheers,

Steve P.
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Old 9th Jul 2009, 8:29 pm   #66
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Default Re: Ekco U29

Success......new valve in place and all is well. Its even back in its case and now understand the meaning of hot...! I thought my U245 got warm but this one well its seriously hot...
All I need now is to source a replacement knob

A massive thanks to all who helped
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