Quote:
Originally Posted by DonaldStott
So what we found was that if you remove the valve and check on a low Ohms range first between pins 4 & 5 of the valve itself, then between 4 & 9 and 5 & 9 you get a reading of 1 - a short/open circuit?
|
I am confused by your result of measuring the resistance of the valve heater. A reading of open circuit would normally be OL and of a short would be 0.5 or what ever the resistance of the meter leads is.
A reading of "1" does not seem likely.
Across pins 4 & 5 (both halves of the filaments) you should get a reading of about 13 ohms. Between 4 & 9 and 5 & 9 you should get about 6.5 ohms as you are measuring each half of the filament.
The heaters may be faulty but I would suggest it is a broken valve pin.
Carefully check the valve socket pins to see if you can see any broken pins.
I carefully use a solid piece of wire the same thickness as a valve pin to push into each valve socket hole to see if there is any friction from the pin making contact with the wire. What ever you do dont use a piece of wire thicker than the valve pins.
Mike
edit
I have just checked on a very cheap £3 meter and and an open circuit resistance is shown as 1.