There is no joy in Mudville tonight.
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Noise with the headphones plugged in, Yes.? Easy to see with scope at C64 feeding the jack tip.
Noise with the headphones and the 6V6's removed, Yes.
Noise at the plate of the 6R7 and T5 junction, Yes.
Noise at the plate of 6R7 without the connection to top of T5 in place, No.? A steady -.77v.
Noise at the unconnected top terminal of T5, Yes.? And bottom (@ R29/C46 tie point).
Headphones don't work now, using scope is difficult as there is now so much fluctuation in the trace (Ch1) no matter what I try to sync Ch2 to.
Removed the "S meter" tie at R30 (but think the 6V6 removal achieves same.? If anything, further removes T5 secondary and 6V6 sockets.)
At the terminal strip holding R29 10K & C46 1mfd, lifted the B+ wire coming up from C44 and Ch1 choke.? This remove B+ feed to remainder of chassis.? Milli-volts of noise seen at open top of T5 terminal, and bottom (R29/C46).
At that point there's nothing driving T5, it's just a conductor for the most part.? The power supply is all that's left.
Replaced both C44, C45 filter caps as I had done during the recapping, using 22Mfd @ 450v.
I don't have a spare 5Z3. (SX-11 has one but I'm not pulling one out of the other working receivers.)
Cobbled together a solid state replacement for the 5Z3, tacked it in bottom side to the empty socket.? No change. ?
(Didn't add the usual CL-140 so just very gradually turned up the variac when powering up.? Also, no need to apply beyond 60VAC before you can see/hear the noise.)
Pulled the Ch1 choke and replaced with a 2K 10W, no change to what I can see on the scope.
Tacked the loose wires back into place to verify I can still hear noise in headphones, receive stations, Yes.? Good, I didn't make it worse.
Pulled the SS replacement 53Z, put the tube back in, put the choke back in, put the 6V6s back in, verified receiver works as it had prior to my hacks and still painfully loud SCP over the speaker.
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When I next get to it, I have a PT I can wire in for the mounted transformer T7, one heavy 320-0-320/5v4A/6.3v4A with nice long leads I use to bench test with.?
If the PT is the culprit I've Xfers from a SX43 & 110 that should fit.
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--
Dan
K1DTS
