Hi all,
My first post to this forum! I finally built the Crack that I ordered last summer over this holiday break. My solder joints all look good, the resistance check came out OK, and the voltage check appeared OK as well. I have a few questions which I can't find answers for in the forums. These topics may be unrelated but perhaps not, so I'm lumping them together into one post.
1) Bell end grounding. I painted the bell end with two coats of a rustoleum primer (both sides) and several coats of a glossy rustoleum. From the forums, it appears that the lock washer on the transformer mounting screw closest to the power switch is especially important when painting the bell end. I used a dremel tool to remove paint and make sure that the washer makes contact. Then I tightened down the other three screws without washers, and they all ended up exposing bare metal under the screw heads. First I cleaned them up and allowed them all to make contact, but changed my mind and used plastic washers for those three. Now my bell end is grounded via the one correct screw, and the other screws should be isolated from the bell end, though of course they might be making contact at the edges of the holes. Does it really matter how many of the screws are making an electrical contact with the bell end?
2) Temperature. The metal plate that everything is mounted to gets warm. I guess I should have expected this, but I thought heat would be limited to the transformer and tubes. It's not too hot to touch, just quite warm. Is this normal?
3) Voltage check. The voltages checked out in the right ballpark, but there was definitely 10-15% variation from the target voltages (as the manual says may happen). But I expected the terminals with a target of 0V to read 0V. A few of them did, but most read something like 1-3mV, and one even read 30mV. Is this small enough to be considered 0V, or does this indicate a possible problem?
4) Clicking/scratching sound through the headphones. This is my biggest concern/annoyance. With no input source connected, there's a scratching sound (kind of like a scratched LP) through the headphones at approximately 2Hz. I'm using a Sonos Connect (playing FLAC rips of my CDs, FWIW), and when I skip to a new song, the scratch sound changes until the music starts, and with some songs the frequency of the scratching sound changes. This is strange, because the sound occurs even when I unplug the input from the Crack, but the nature of the sound appears to be influenced by the input signal. Turning up the headphone volume increases the music volume, but not the scratching sound, so I can drown it out, but it's pretty annoying at a low listening volume. I'm burning the system in right now, but after a few hours the scratching sound is still there... Any ideas?
Thanks!
Derek
