Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: afilen on June 21, 2021, 05:01:02 AM
-
Build just finished, resistance check went off without a hitch, but voltage check had one and only problem, Terminal 9 showed 140V. Turning off the amp produces a loud buzz in the right channel, no sound in the left channel, and this is with/without RCA cables. Posted some pictures, any help is appreciated!
-
I see some very long leads on one of the 220uF power supply capacitors. It also doesn't look well soldered.
You have no wire connected to B4. You have two wires connected to B3. This is not correct.
-
Noted! I'm getting some replacement Hlmp-6000 LEDs on Friday due to one breaking in the process. Can I still run my voltage checks in the meantime with only 1 of the LEDs connected?
-
If you connect a jumper wire between A3 and A8, you can do that.
-
Re-wired B3 and B4, and tidied up the capacitors. Resistance and Voltage checks passed, nothing over the limits now. Got both tubes glowing. Now I get still get a decent buzz in both channels, both with and without RCA cables. When building the kit, I never received #8 star lockwashers to go between the transformer cap and the transformer itself. The locknuts with teeth are properly tightened, per instructions. And of course, during this process, I managed to mangle the LEDs completely. Re-did the resistance and voltage checks and everything was within limits once again. If I take out the 12AU7 vacuum tube, the buzzing stops.
-
If you pull the 12AU7 out of the amp while it's running, that's just not OK on many levels. You may do some serious damage to the 6080 or the amp itself by doing that.
Can you post the voltages you have on 1-10?
Buzz in both channels would have me suggesting that one of your 220uF capacitors is loose.
-
1 - 60V
2 - 171V
3 - 0V
4 - 171V
5 - 60V
6 - 0V
7 - 103V
8 - 0V
9 - 103V
10 - 0V
-
With the volume pot all the way down, is the buzz still there?
-
Yes, increasing or decreasing the volume pot does not change the volume of the buzzing at all
-
This would suggest a loose 220uF capacitor, possibly a different loose connection, or just loose hardware in general. The lack of #8 star washers shouldn't cause major issues.
-
Reflowed and trimmed as much of excess leads as I could, not seeing any gaps in the joints from my end but the problem still remains. Buzzing in both channels regardless of volume or RCA inputs
-
Can I see an overall shot of the top and bottom?
-
Here ya go, let me know if you need me to take more of particular components
-
If these touch, you will run into some bad issues, but this isn't going to cause buzz.
-
3U does not look to be soldered and the leads need to be trimmed back.
A9 does not look well soldered.
The wire going into A4/A5 has too much jacket stripped off.
I would definitely want to see the wiring of the headphone jack.
-
Trimmed 3U and resoldered, resoldered A9. I also switched the 12AU7 tube to a new one from Amazon and now I only have a very faint hum in the left channel. Connected my DAC via RCA and am able to get sound in the left channel, but even after turning the volume to near max on the Crack, the music is far too quiet. New pics added
-
Checked my voltages again and they are in the 170V range once again, so I’ll have to see if there’s any crossed wires
-
Checked my voltages again and they are in the 170V range once again, so I’ll have to see if there’s any crossed wires
Which voltages are 170V? That would be appropriate for T2, T4, B2, and B5.
Where the black wires on the headphone jack meet doesn't look well captured by soldered.
-
Cleaned off and resoldered where the 2 black wires meet on the headphone jack. No hum/buzz anymore. Connecting it to my DAC, I hear no sound unless I turn up the volume pot to the max - and even then, it is barely audible through the headphones. Currently testing with ZMF Auteurs
-
Cleaned off and resoldered where the 2 black wires meet on the headphone jack. No hum/buzz anymore.
How are the voltages?