Loud Buzzing + Occasional Popping [solved]

Adelz · 1843

0 Members and 1 Guest are viewing this topic.

Offline Adelz

  • Jr. Member
  • **
    • Posts: 48
on: May 20, 2015, 10:20:44 AM
I'm in the process of building my second Crack kit and have run into a problem. I completed the circuit and both the resistance and voltage checks are within 10-15% of those listed; the numbers can be seen below. The voltage of the headphone TRS jack gets up to 7.7V on startup so that is also normal. After powering it on, there is constant and fairly loud buzzing as well as some occasional crackling. Plugging my headphones into the TRS jack does result in loud popping each time it goes past a ring terminal. The buzzing stays the same regardless of the volume level. I replaced the tubes and the problem was unchanged. I also tried a different power cord and that made no difference.
 
Whether or not the RCA cables are plugged in makes no difference either. When testing audio, the sound is very clear and the only problem continues to be the loud buzzing in the background (it stays in the background as opposed to affecting the audio being played through the amp). I tested all the grounds listed in the stickied thread and all of them read 0 other than Terminal 4: with one grounding point clipped to terminal 3, as instructed in that thread, and the other on terminal 4, the voltage continues to rise into the hundreds of Kohms. 
 
I'm not sure what the best course of action is for troubleshooting due to the correct resistance and voltage checks. I'm assuming I have a bad resistor; maybe the 22.1K resistor between terminals 4 and 5?
 
Thanks,
Andrew

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fpuu.sh%2FhUvUd.png&hash=31adee9dfd404459a4d36c35c7799e342a8b3ae5)
« Last Edit: May 20, 2015, 10:47:08 AM by Caucasian Blackplate »



Offline Doc B.

  • Administrator
  • Hero Member
  • *****
    • Posts: 9641
    • Bottlehead
Reply #1 on: May 20, 2015, 10:30:47 AM
Check the attachment of your power supply filter capacitors.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline Adelz

  • Jr. Member
  • **
    • Posts: 48
Reply #2 on: May 20, 2015, 10:44:00 AM
Thanks so much! I'm pretty sure that was the problem and it seems to be functioning perfectly now.



Offline Doc B.

  • Administrator
  • Hero Member
  • *****
    • Posts: 9641
    • Bottlehead
Reply #3 on: May 20, 2015, 10:51:21 AM
I get to keep the corner office for another month.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline Adelz

  • Jr. Member
  • **
    • Posts: 48
Reply #4 on: May 20, 2015, 11:02:11 AM
Haha, I guess so. Your post solved the background noise, however the occasional popping/crackling was still happening. Tapping the power tube made it pretty obvious that it was the problem. I've replaced it and now the amp is working perfectly. Who should I contact for a replacement power tube?



Offline Doc B.

  • Administrator
  • Hero Member
  • *****
    • Posts: 9641
    • Bottlehead
Reply #5 on: May 20, 2015, 11:10:41 AM

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline Adelz

  • Jr. Member
  • **
    • Posts: 48
Reply #6 on: May 20, 2015, 11:39:05 AM
Thanks.