Bottlehead Forum
Bottlehead Kits => Eros Phono => Topic started by: gabriel on April 13, 2020, 03:54:55 PM
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I just completed construction of the Eros 2 and am wondering whether I have a bad tube and/or broke it.
Just after completing I listened to some music and it sounded wonderful at reasonable volumes. However at semi-loud volume with nothing playing there was a fluttering in the left channel (helicopter sound), and a pretty reasonable buzz in the other channel.
Today I went through the wiring again and discovered some untrimmed wires touching the metal chassis. I trimmed those, and there's much less noise and buzzing only at even higher volumes. However one channel is now VERY quiet. When I swap the EF86 tubes, the quiet channel swaps. The tube which was generating the helicopter sound is now the very quiet tube.
Did I kill the tube? Is the tube dead / the problem do you think? Thanks for any help.
edit:
I just redid my resistance and voltage checks. They were perfect immediately after completing the build. Now the voltage checks are not.
IA, IB 210-230V --> 215.2, 214.5
OA, OB 155-185V --> 168.5, 145.0
OC, OD 95-100V --> 95.3, 114.0
OkA, OkB 95-105V --> 96.7, 113.8
OkC, OkD 0.7-2V --> 1.28, 0.007
Do you think these measurements indicate a failed tube?
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The OKC/OKD voltage follows an EF86?
If so then yes, it's possible that one of those leads touching the chassis exhausted the EF86. I just wrapped up an Eros 1 repair last week that had a similar issue that destroyed a brand new EF86 in the process.
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Thanks Paul. Those voltages do in fact follow the "bad" EF86. Looks like I killed a tube.
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Oh yeah, that tube is just totally refusing to conduct!