14-01-2022, 07:51 PM
With a view to this event I had an unfortunate event today.
I like to think that I am a totally rational person but just now and again I tease myself with irrational thoughts. This happened today. I was running three sets simultaneously and adjusting the relative distribution of aerial signals for best performance. All of a sudden my HMV901 suffered a line collapse reducing its width to about 1". This set is normally very stable and reliable but here I was running it alongside others competing for its signal. Clearly a case a jealousy!
My first thoughts were to swap the line oscillator valve and the output valve but no change. Then in my depressed state thoughts turned to the worst possible failures. So I checked the output transformer and it looked OK, next the oscillator transformer and things were looking up for it was OK too. Must be the output anode choke? Nope, well that's good let's check the anode feed to the oscillator. Great! The 500K was open circuit. Raking around I found a suitable dog bone and gathered my tools and soldering iron at the set.
Having extracted the O/C resistor I then looked around for my replacement. I looked absolutely everywhere but it was nowhere to be found. After half an hour of fruitless searching I eventually discovered that when moving things in position I had placed the Anglepoise base on top of the resistor.
Well you might have expected things to come to a rapid conclusion after all that, but no. The combination of getting the Anglepoise to illuminate the spot and messing with head magnifiers and shakey hands meant that it must have been about another hour before I actually managed to solder the thing in place (badly).
However, at least the set now powered up with the correct width. Perhaps I'll think twice about sharing its aerial signal with other sets from now on.
Peter
I like to think that I am a totally rational person but just now and again I tease myself with irrational thoughts. This happened today. I was running three sets simultaneously and adjusting the relative distribution of aerial signals for best performance. All of a sudden my HMV901 suffered a line collapse reducing its width to about 1". This set is normally very stable and reliable but here I was running it alongside others competing for its signal. Clearly a case a jealousy!
My first thoughts were to swap the line oscillator valve and the output valve but no change. Then in my depressed state thoughts turned to the worst possible failures. So I checked the output transformer and it looked OK, next the oscillator transformer and things were looking up for it was OK too. Must be the output anode choke? Nope, well that's good let's check the anode feed to the oscillator. Great! The 500K was open circuit. Raking around I found a suitable dog bone and gathered my tools and soldering iron at the set.
Having extracted the O/C resistor I then looked around for my replacement. I looked absolutely everywhere but it was nowhere to be found. After half an hour of fruitless searching I eventually discovered that when moving things in position I had placed the Anglepoise base on top of the resistor.
Well you might have expected things to come to a rapid conclusion after all that, but no. The combination of getting the Anglepoise to illuminate the spot and messing with head magnifiers and shakey hands meant that it must have been about another hour before I actually managed to solder the thing in place (badly).
However, at least the set now powered up with the correct width. Perhaps I'll think twice about sharing its aerial signal with other sets from now on.
Peter
