04-12-2018, 09:03 AM
Hi.
Welcome to the Forum, you'll get sound advice form the people here.
It's always an idea not to run up a set after years of not being used. I often say to people would you start a car that has been sitting for 30 or more years without checks etc.
Inevitably these sets will as has been said need a few capacitors replaced. Just plugging in a radio to mains is fraught with possible problems, the main smoothing capacitors need a slow awakening so one of the things you should make is a lamp limiter if you dont have a variac, this reduces the current available to run the set as the "Bulb" is in series with the mains to the set, you can use different wattage bulbs to vary the current available to the set. A filament or Halogen bulb has to be used and wattages from 15, 25, 40, 60 & 100 can be used to gradually bring up the set. When it comes to resistors valve sets are very forgiving with values that have gone high and I'd concentrate on coupling and de-coupling capacitors initially. As has been said the grid capacitor to the output valve should be an automatic replacement and the smoothing capacitors not subject to sudden full voltage, the fact you have replaced the AZ31 makes me think the set is drawing more current than it should, even a tired AZ31 will normally work fine in a radio, the AZ31 is what is known as a directly heated rectifier, a good enough valve but they pass current very quickly and if running with full mains the smoothing capacitors charge up very fast with no load from the other cold valves, another good reason to make a lamp limiter or use a variac.
Take your time don't rush and enjoy the restoration.
Welcome to the Forum, you'll get sound advice form the people here.
It's always an idea not to run up a set after years of not being used. I often say to people would you start a car that has been sitting for 30 or more years without checks etc.
Inevitably these sets will as has been said need a few capacitors replaced. Just plugging in a radio to mains is fraught with possible problems, the main smoothing capacitors need a slow awakening so one of the things you should make is a lamp limiter if you dont have a variac, this reduces the current available to run the set as the "Bulb" is in series with the mains to the set, you can use different wattage bulbs to vary the current available to the set. A filament or Halogen bulb has to be used and wattages from 15, 25, 40, 60 & 100 can be used to gradually bring up the set. When it comes to resistors valve sets are very forgiving with values that have gone high and I'd concentrate on coupling and de-coupling capacitors initially. As has been said the grid capacitor to the output valve should be an automatic replacement and the smoothing capacitors not subject to sudden full voltage, the fact you have replaced the AZ31 makes me think the set is drawing more current than it should, even a tired AZ31 will normally work fine in a radio, the AZ31 is what is known as a directly heated rectifier, a good enough valve but they pass current very quickly and if running with full mains the smoothing capacitors charge up very fast with no load from the other cold valves, another good reason to make a lamp limiter or use a variac.
Take your time don't rush and enjoy the restoration.
