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Are all 19kc coils created equal?

Carbsandcaps

Carbsandcaps

Super Member
Working on my Sansui 250 tube receiver that I’ve been listening to for a while now. Did a full recap and it sounds great but the multiplex never worked. I swapped it out today and decided to take a look at it and found 0v on pin 6 of the 6aq8. Turns out the primary coil of T7 is open. It’s the 19kc oscillator coil. Trying to find an exact replacement is next to impossible but I’m wondering if any 19kc oscillator would work or are these particular to a brand. The part number comes up with nothing. It’s MST-7A in the picture. IMG_4770.jpegIMG_4762.jpeg
 
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If you're getting 0V on pin 6 of V6, the problem is R41 not the transformer. The primary of the transformer goes to pin 1 of V6.

Per the transformer specifically, no, not all transformers are made equally. This one appears to have a ~12-15 mH inductance on both the primary and secondary. If it is indeed bad, take it apart and see if you can re-solder the (very, VERY) thin wire back onto the terminal. Note this is very delicate. You might also be able to tease the wire out if it's broken. Unwinding one turn to get enough to re-solder won't make any difference.
 
Yes I’m sorry pin 1. I was going to attempt to disassemble it and hopefully it it noticeably broken. I’ve fixed a few transformers before but I’m thinking this wire will be the smallest yet.
 
w3jn said:
d see if you can re-solder the (very, VERY) thin wire back onto the terminal. Note this is very delicate. You might also be able to tease the wire out if it's broken.
Click to expand...

Did this on a pair of tweeters once, its like soldering human hair. Extremely fussy, but not impossible. Magnification helps a ton.
 
I had an open transformer on a Sony STR-6060 I had. We were able to swap it with another one inside the unit that only needed one leg.

By putting the component with the failed leg on place of the component needing only only one leg, problem was solved!

Search for "STR-6060" or "MPX" by "Whitehall"
 
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