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December 03, 2020, 05:45:07 AM

Recent Posts

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1
Crack / Re: Bay Area Crack Repair
« Last post by dodossssssssss on Yesterday at 06:24:25 PM »
I can't thank you enough! It's working and sounds better than I remember. Thank you so much for helping me out with this! I was at my wits end trying to figure this out on my own but am ecstatic to have it working again.
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Crack / Re: Bay Area Crack Repair
« Last post by dodossssssssss on Yesterday at 05:31:17 PM »
Thank you! I'll get started soldering again tonight and let you know how it goes. I'm using 60/40 with rosin core. I think I got it from ace hardware back when I first built the Crack.
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Crack / Re: Bay Area Crack Repair
« Last post by Paul Birkeland on Yesterday at 05:08:48 PM »
You need way more solder on your joints.  You also need to heat the joints longer to let the solder flow out.  Out of curiosity, what kind of solder are you using?
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Crack / Re: Bay Area Crack Repair
« Last post by dodossssssssss on Yesterday at 03:56:34 PM »
I've attached the photos. If you want better pictures of any specific part please let me know.
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General Discussion / Re: Coupling cap installation
« Last post by Paul Birkeland on Yesterday at 02:22:09 PM »
The primary impedance of the OT in the Mainline is 4K.  I believe you'll hear a bigger difference from a nicer cap more than going from 10uF to 15uF.
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Crack / Re: Bay Area Crack Repair
« Last post by Paul Birkeland on Yesterday at 02:20:51 PM »
We see a blown power transformer about every 5 to 10 years.  If the tubes are still glowing, your power transformer isn't blown.

Could you post some photos of your build?
7
Crack-a-two-a / Re: TwoQuiet Fine Attenuator Problem
« Last post by Doc B. on Yesterday at 12:55:38 PM »
If it's going to mono from stereo that would indicate that left channel and right channels are shorting together somewhere. That sounds like it could be a problem at the wiring going into or out of the switch, since it would involve somehow shorting together two different decks in the switch.
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Crack-a-two-a / Re: TwoQuiet Fine Attenuator Problem
« Last post by Deke609 on Yesterday at 12:23:01 PM »
Sometimes I can just jiggle the knob slightly to restore stereo ...

That points to a loose solder connection - my guess would be one of the black ground wires.

cheers, Derek
9
Crack-a-two-a / TwoQuiet Fine Attenuator Problem
« Last post by Bubbatwoa on Yesterday at 10:03:13 AM »
I finished building my C2A a couple of weeks ago, and everything tested within spec.  After a day of listening, I installed the TwoQuiet upgrade.

The problem I'm having is, when I turn the fine attenuator knob from one position to the next, about 75% of the time the sound immediately collapses to mono.  Sometimes I can just jiggle the knob slightly to restore stereo, and other times I can go one more position and then come back to the previous position to get stereo back.  In other words, starting from position 1 (stereo), I turn to position 2 and get mono.  Turn to position 3 (also mono), then back to 2, which is now stereo.

Every position on the fine adjustment experiences this problem.  It doesn't matter which position you start from or what direction you turn the knob.  Again, it happens about 80% of the time and it doesn't matter which direction you're turning the knob.  I can always get stereo back one way or another, but it's quite annoying to have to play with the knob almost every time I turn it.

The coarse adjustment attenuator is rock solid, and it's position has no effect on the behavior of the fine adjustment with respect to the symptoms.

Since the trouble isn't happening consistently, I tend to think the attenuator itself is faulty rather than the wiring or solder joints.  I have no idea what would cause the stereo signal to revert to mono upon changing the position.  I've inspected the solder joints and they all look good.

As the manual recommended, I turned the knob repeatedly through it's range, both slowly and very quickly, in hopes of cleaning the contacts a bit.  I didn't use any DeOxit.  Should I try it?

Any suggestions as to what might cause this type of problem?

edit:  I should mention that the fine attenuation works as expected.  The volume goes up and down in predictable steps as I turn the knob.  It's just that the signal becomes mono when I select a new position 80% of the time.
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Crack / Re: Bay Area Crack Repair
« Last post by dodossssssssss on Yesterday at 09:09:22 AM »
Thank you for the response! I just attempted to reheated every joint till the solder was flowing and found that terminal 10 was not properly secured with solder so I added some to it but this hasn't fixed the issue. I also noticed some gunk (looks sort of like melted plastic) on PT-10 terminal 13. The black wires on the headphone jack are both very secure on each of the joints that they go through. The LED's still don't light up despite the tubes lighting and warming up. Could the PT-10 be blown?

Also, I realized that the resistance readings on the rca center pins are correct, my multimeter just doesn't go high enough and since they read somewhere above 50k I assume they are at the correct resistance.
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