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OLDER DECWARE GEAR SUPPORT >> SE84A, SE84B, SE84C, SE84C+,SE84CKC >> weird problem SE84C
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Message started by Warren N CA on 04/05/13 at 00:06:15

Title: weird problem SE84C
Post by Warren N CA on 04/05/13 at 00:06:15

I have two SE84C that I used bridged, one complete two channel amp per stereo channel.

Both channels of one amp stopped working (no output). I am an experienced tube technician, so put it on the bench to fix. But this one is really confusing me. All voltages measure good. I can trace a sine wave as far as the anode on each output tube, but it does not appear at the output transformer secondary on either channel. The DC resistance of the secondaries, according to my Fluke 87 is 0.8 Ohms, same as my working amp.

Is it possible that BOTH output transformers have failed simultaneously?

Or do I need a long overdue vacation playing miniature golf or something?

Title: Re: weird problem SE84C
Post by Brett on 04/05/13 at 02:49:29

How about the primaries? If you are getting a sine wave at the output anode then that is puzzling. The power supply is filtered using the primary so you might look at possible grounding issues there. Try swapping the rectifier and then play miniature golf.

Title: Re: weird problem SE84C
Post by Warren N CA on 04/06/13 at 03:17:48

I have now replaced all tubes, including the rectifier. Everything still points to output transformers, but I still can't believe it. So I'm gonna replace a bunch of other parts that at least I have on hand here before I bite the bullet and order transformers. Thanks for your suggestions!