Sunn 200S blown OT

[george]

My son posted a note on this board looking for advise on repairing his 200S. I believe the OT is shorted since all tubes check out okay. The amp is exhibiting very low gain after the output was shorted with close to max output.

  The high impedance side of the OT reads 22 ohms grn to red (center tap) and 72 ohms blue to red. The other side is about the same (10% difference in values). This will only give me a diagnostic for an open not a short anyway. Appreciate any other helpful hints. I would also like any info on replacement OT suppliers.

Thanks,

george

[Anonymous]

Hi George I got your PM.  In my opinion your output transformer IS toast.  The discrecency between the legs should not have exceeded more than an ohm or two.  50 ohms is WAAAAAAAAY too much.  It depends on how original you want to keep the amp, I would send it to Mercury Magnetics and get the original rewound.  www.mercurymagnetics.com

[george]

Thanks for the info any idea what the cost would br to rewind? Does Mercury also have a 200S replacement OT (the site just had a 2000S - $300 - ouch).

george

[Anonymous]

I doubt they have a 200S tranny, because they aren't that popular, and get ready the rewind is going to be about that much.  Let me know how you make out