Transformer...tests faulty ?

[petemoore]

  Fischer Stereo Tuner/Amp iron.
  I have all leads open exept where I connected for testing.
  two leads come in from AC supply, I put 8vdc across them, the primary.
  I tested across many lead combinations of the wires coming out of the other hole diamond pattern weave with colors
  Yellow/Black weave
  Yellow
  Red
  Green
  Blue
  Orange
  Six wires from the right hole
  -------------
  Two wires from the left hole
  Y/B
  B
  I didn't find voltage across any of the six secondary wires, I also found what reads as 'open' on the primary, I believe the primary is open, and I'm testing a faulty transformer. The primary reads 0.0hms, and doesn't register on the Diode checker, voltage from battery remains the same when tested, then tested with the primary wires attached.
  either that or I'm missing something...
 
 

[jrc4558]

shouldn't you have an AC voltage for testing a transformer? I think they decouple DC completely.

[Aharon]

Too many clues lead to a faulty transformer,I'd say it's fried.
Do you have onre of thse home made light bulb current  limiters?
Aharon

[Aharon]

Oh yeah,test with AC on the primary.
Aharon

[petemoore]

shouldn't you have an AC voltage for testing a transformer? I think they decouple DC completely.
 I thought about typing that^, but recall the battery mentioned in a transformer page could be used to find the turns/voltage ratio. I gotta little AC dapter, small volts I can try, but I can probably just find out if AC transformer is a different beast to test than DC transformer.
  Edit, thanks aharon, will try an AC source...

[petemoore]

Daft, the AC source has hidden itself...
  I did read put 10v battery across primary and test secondary voltages..pretty sure..
  shouldn't you have an AC voltage for testing a transformer? I think they decouple DC completely.
  If this is true, I'll be looking for that AC WW, small voltage, because my reading of exact same DC voltage from battery and battery w/primary attached would be 'normal' or useless as a test.

[mdh]

DC on the primary won't induce a current in the secondaries... it has to be AC. http://en.wikipedia.org/wiki/Transformer.

I believe there's a page on GEO somewhere about testing an unknown transformer.

[petemoore]

  k..5vac adapter.
  Reads same voltage with primary circuit in, and not connected.
  And nothing seems to be coming out the other side.
  So I'm pulling this out, saving the nice frame, and grabbing the next one.

[mdh]

Just one last thing... you are setting your meter to AC volts when you test the secondaries, right?

[petemoore]

  Good call MDH, but yupp, for some reason I've managed to get the distinction between settings for Ac and Dc on the meter before testing mostly I think.
  So forget the battery as iron test power source.
  Adapter putting out 5.6v AC...did some testing, trashed that iron, deemed unacceptable for further study, so I took it apart for the bolts and copper and the view of the smoke path. the end plates make good part holders.
  I don't know where to put the scrap iron and windings, in the trash or the recycle.
  Second transformer under test soon shows;
  when 5.6vac is applied to the two right side red wires, I get 23.2vac and .9vac from the two grey solid core wires.
  When 5.6vac is applied across the two orange wires right side, I get 10.7vac from the yellow and white wires on the left side, .3vac from the grey ones.
  So about 4:1 and and 1:4 ratios when using the red 'primary'
  And about a 2:1 and 1:2 ratios when using the orange 'primary'.
  I'm not even certain I have the 'primary' and 'secondaries'...maybe it's intended to work reversed...dropping voltage...I haven't looked at a reciever schematic to see what voltages these Big RCA BJT's in the heat sinks were run at. the B/E diodes test good.
  Any suggestions as to what applications such an iron could be used for, or how to figure that out...
  Seems like I could have ~440vac, then Bridge Rectify to get DC volts, that should be a good amount, possibly enough for a tube output section, or perhaps a Mosfet Amp of some type.
  The transformer is a large one, I don't know how that equates to current rating.