06-05-2011, 06:48 PM
Hopefully this will me my last report on this set (said he crossing fingers and touching wood). I had better warn the likes of Alan B and Yorkie not to read on as the fix is nothing like to their high standards as it's involved 'Thinking outside the box' of which Oliver Bulleid would be proud.
I got my new reistors and capacitors yesterday and fitting these reduced the hum but it was still loud enough to be a PITA, especially at low volumes.
I have some knowledge of general electronics but very little of valves but one thing of which I am possessed in spades is low, base, animal cunning.
I've stuck a silicon rectifier and capacitor onto the LT to power just the iffy EBC81. I also incorporated an LM317 and with the heater voltage trimmed down to 3.2v there's no hum. A happy side-effect has been to lower the minimum volume.
[attachment=1190]
The speaker seems OK if positioned upside down so hopefully all will continue to be well until I get my mitts on a replacement valve.
Just in case anybody has noticed my post about this 'elsewhere' no offence was intended. It was just that there's more people on that and I was getting concerned that I was asking too much of the members of this forum - I need to save some credit as I'm yet to touch my Echo and it doesn't work on VHF so will certainly need assistance on that.
All the best
- Joe
I got my new reistors and capacitors yesterday and fitting these reduced the hum but it was still loud enough to be a PITA, especially at low volumes.
I have some knowledge of general electronics but very little of valves but one thing of which I am possessed in spades is low, base, animal cunning.
I've stuck a silicon rectifier and capacitor onto the LT to power just the iffy EBC81. I also incorporated an LM317 and with the heater voltage trimmed down to 3.2v there's no hum. A happy side-effect has been to lower the minimum volume.
[attachment=1190]
The speaker seems OK if positioned upside down so hopefully all will continue to be well until I get my mitts on a replacement valve.
Just in case anybody has noticed my post about this 'elsewhere' no offence was intended. It was just that there's more people on that and I was getting concerned that I was asking too much of the members of this forum - I need to save some credit as I'm yet to touch my Echo and it doesn't work on VHF so will certainly need assistance on that.
All the best
- Joe
