Little help, please? [resolved]

[bAd]

With a little help of the people from the service department my first DIY amp is finally running!  I'm still in the process of burning the uint it.  Unfortunately after three days of listenig the amp started making noise in the left channel. It sounds just like described in the manual scratchy, hissy, crackling. I know it's not the  bad tubes as i tried to swap the left with the right one.  No luck. (cold joint somewhere?)  When I got it back from the repair I was told that the tube sockets were super dirty.  I just wanted to ask if any of you guys could help me identify the problem.  Or maybe point me in the right direction.
Thanks. bAd

 

[Doc B]

Was this a repair we did?

 

[bAd]

Hi Doc. Yes, I just got the amp back on Friday, but this particular problem occurred just now and when I sent it for repair I didn't mentioned that on the list of issues.  So by any means I'm not trying to blame your crew for it.  I was the one who solder stuff wrong. Lol.  Anyhow how do I go about this problem?
Thanks.

 

[Doc B]

Try rocking the tubes a bit in the socket while it's running.

 

[Strikkflypilot]

Are You sure there is nothing near Your amp supplying noise, some sort of wireless communications device? Wireless speakers, WIFI... I had a media center bugging me, and it wasnt even wireless, still produced RF noise, I guess..

Edit: Oops, just realized You may not have read Doc's latest reply above mine before I add another one. Sorry.

 

[bAd]

Hi, rocking tubes in place did not change anything.  But somehow an idea popped in my head to go go ahead and re-solder all the joints at the tube socket and all the wires connecting the left channel pc board with power supply board on both ends, etc, etc. That fixed the problem.  So it was just a simple cold joint that I didn't even know how I found, but everything has been working fine with no issues for good 10 hours. I'm keeping my fingers crossed.  . Thank you for your time.

 

[bAd]

Hi again. Just like I was expecting, the quick fix would have been too good to be true. The raspy scratchy noise is back. Same left channel, tubes are not damaged. I noticed, that a gentle tap on the top  metal plate can get rid of the noise, a few more taps will bring the noise back. Where should i look for the source of the problem? The noise reminds me of a broken inside xlr sound.
Thank you.

 

[Strikkflypilot]

I had the same issue. Turned out I had connected a wire to a terminal and completely forgotten to solder it. This definitely sounds like a soldering issue...cold solder joint, forgotten soldering or such. Just my to cents, though...

 

[bAd]

Thanks. The gun is warming up.

 

[bAd]

Re-soldering the terminals and all possible connections didn't help. Does any of you guys think that it could be something on a left channel PC board?

 

[bAd]

Not the PC boards. I just swapped them around. No idea what it could be.

 

[Doc B]

Tighten all your screws.

 

[bAd]

Hi Doc. All the screws were tight. However I was able to find the problem somewhere else. Going back and forth, slowly eliminating possibilities I exhausted all the options. Then I flipped the plate, connected the amp to the power, connected the headphones and on the amp turned on I gently tapped all the usual suspects one by one with a screwdriver. (I know. Not exactly a "PRO" thing to do, but I was desperate). That led me to the regulatory board. That's where the problem lived. After re-soldering all the joints.... we're back in business. Again... keeping my fingers crossed!

 

[Mike V.]

Hi Doc. All the screws were tight. However I was able to find the problem somewhere else. Going back and forth, slowly eliminating possibilities I exhausted all the options. Then I flipped the plate, connected the amp to the power, connected the headphones and on the amp turned on I gently tapped all the usual suspects one by one with a screwdriver. (I know. Not exactly a "PRO" thing to do, but I was desperate). That led me to the regulatory board. That's where the problem lived. After re-soldering all the joints.... we're back in business. Again... keeping my fingers crossed!

That sounded so dangerous, be careful amigo

 

[jjvornov]

That sounded so dangerous, be careful amigo

And dangerous to the amp. It would be easy to short out a component or board by putting the conducting metal across contacts inadvertantly. A loud pop and puff of smoke may ensue. A chopstick is often recommended to avoid putting anything that is conducting in and around the live circuits.

James

 

[bAd]

Hell yeah! I was super careful. Desperate times call for desperate measures. It was the last resort to go that far. Lipstick is a good tip.