7c53bc94   
   From: nasadowsk@usermale.com   
      
   In article   
   ,   
    Travis  wrote:   
      
   > on an early stereo Q160 ( chassis SHFA2 ) I am going through some   
   > spare amps and trying to figure out whether the transformers are any   
   > good. I ohm'd out 3 different Output Transformers and they all read   
   > the same to within an ohm or so BUT they all were unsymetric in the   
   > same way which causes me to believe the winding is partially shorted,   
   > but all 3? and the same to within an ohm?   
   >   
   > Center Tap to each grid reads 30 ohms but grid to plate reads 50 ohms   
   > for one tube and 75 for the other in the pair --- in every case. These   
   > are with the 6973 tubes, the sockets were empty of course and there   
   > are no other components attached to those leads so I am measuring just   
   > the winding resistance.   
   >   
   > Anybody ever see this before?   
   >   
   > Thanks in advance for your comments, Travis   
      
   I once figured out I had a bad transformer on an AMI D by adding a very   
   low voltage (like 2 or 3) AC to the speaker, with no tubes or speaker   
   hooked up (!), and looking at the waveforms on a 'o scope at each tube   
   plate.  With the unit off.  They should be opposite, symetrical, and   
   more or less cancel if added.  Bonus points if you've got an audio   
   generator - you can sweep the band.   
      
   In a pinch, a 6.3V transformer, variac, and voltmeter can do a good 'go'   
   'no go' test.  Suicidal folks will just use a variac >:)   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)