[Amps] Trio TL-922 Filament Transformer...

[r391]

Tonight I decided to pull some PM on my Japanese Trio TL-922...

Filament voltage 4.8 volts... at the tube pins... thought hmmm... better a 
little low than a little high?

Felt the filament transformer and it felt quite warm after only 5 minutes 
or so of operation...  this is the first time I've done this so I don't 
know how warm the transformer should feel after 5 minutes so...

Out of curiosity I decided to check mains input voltage to the filament 
transformer and it was 122 volts on one leg and... 102 volts on the other 
so that the two primaries input voltages are unbalanced to each other by 20 
volts...

Thinking "that can't be right" as the schematic shows "0" to "0" and "120" 
to "120" between the two transformers so that  their both shown to be 
phased the same way and that my 122 volt line voltage should appear on all 
of the primary windings equally... I decided to trace the wiring.

Found the installed wiring different from the schematic...  this difference 
is either from the factory or by previous owner design but is such that one 
of the 120 volt lines from the filament transformer is connected to the 100 
volt connection on the HV transformer thus feeding one of the filament 
transformer primaries 100 volts instead of 120 volts while the other 
primary was connected to the 120 volt connection on the HV transformer and 
receiving 122 volts...

Was wondering if this is a factory wiring error or a deliberate attempt by 
the factory or a previous owner to adjust the filament voltage... anyone 
seen this before?

tnx, Ott


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