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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

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Old 8th Feb 2006, 12:26 am   #1
Station X
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Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
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Default DAC90A. Heat shielding of dropper resistor?

Should the dropper resistor of a DAC90A have any form of heat shielding? I know that the dropper in the DAC90 is wrapped in asbestos, but this doesn't seem to apply to the DAC90A.

The one I am working on has burnt/melted sleeving on wires close to the dropper and the paxolin board to which the dropper is screwed is blackened. All the components in the set test OK apart from the coupling capacitor feeding the UL41, which is leaky. Could this have resulted in enough excess current through the dropper to do the damage? The UL41 is actually OK according to the valve tester! O/P transformer is OK too.

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Old 8th Feb 2006, 12:30 am   #2
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Join Date: Jan 2005
Location: Oxford, UK.
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Default Re: DAC90A. Heat shielding of dropper resistor?

Hi Graham,

No, there's no heat shield as far asI can remember.

I think your capacitor theory could well be right. Other causes, I suppose, could be incorrect voltage setting, or running the set hard up against a wall, depriving it of ventilation

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