Tube AMP problem! Please help me.

  • Thread starter Thread starter AngeloG.
  • Start date Start date
A

AngeloG.

New member
Hello, I am facing a diffuculty with my amp.

I started getting this weird crackling noise, about 3-4 minutes after the amp starts heating up. There is a photo of my amp, Peavey Valveking 112.

pict0297.jpg


And tube model:

pict0300.jpg


I will also post a sound sample in a couple of minutes.
I read, the most possible thing is the preamp tube's fault. But I have no idea about which tubes I need, how to install them, if they are compatible, etc. Please help me :)

EDIT:And here is the sound sample: Download noise.mp3 - Kiwi6.com Hotlinking
 
That's probably a cold solder joint. As the amp heats up and thermal expansions take place, the connect becomes a high resistance point.

As a first step re-seat the tubes and exercise any loop jacks.

Does tapping on the amp while it's sizzling change it?

Cold solder joints are usually diagnosed fairly easily with freeze spray.
 
I was able to re-seat the power tubes, however I can't seem to find how to remove the small ones, I remove the cap, but then how do I unplug them? And what does "exercise any loop jacks" mean?

Appreciate the response.
 
The pre-amp tubes should just pull straight out once the covers are off.

I think he means either wiggle them around ("exercise") or get them out of there ("perform an exorcism.")
 
stevieb said:
The pre-amp tubes should just pull straight out once the covers are off.

I think he means either wiggle them around ("exercise") or get them out of there ("perform an exorcism.")
Click to expand...

Well..wiggle around what?
 
AngeloG. said:
I was able to re-seat the power tubes, however I can't seem to find how to remove the small ones, I remove the cap, but then how do I unplug them? And what does "exercise any loop jacks" mean?

Appreciate the response.
Click to expand...
Remove the tube cover and gently wiggle them in the socket. Make sure they are seated all the way in the socket. Then wipe the tube off with a cloth.

Exercise the Loop Jack is take a plug and insert it remove it several times fast.
 
I reseated all the tubes, now I wait for it to warm up. So that loop thing, I must insert a plug on all inputs some times quickly?

EDIT: No avail, tried it..
 
if it's a bad solder joint ( a common problem) you're gonna have to take it to a tech.
It something that some folks could check themselves but if you don't even know how to deal with tubes you're still too much of a newbie to be able to get that deep into it.
 
I don't know what else to do, as far as electronics go, I happen to study them, I just have no experience about where is every part on the amp.
 
I took the circuit board out, I can't see anything unusual. What should I look for?
 
well .... a bad solder joints gonna show in one of two ways.
Sometimes they'll be a dull grey while all the other joints are shiny.
Sometimes though they'll be nice and shiny but will show fractures right around the wire that's been soldered.
These fractures will ONLY be visible with a very strong magnifying glass and a bright light. They're tiny ... but it'll look like a tiny crack running around where the wire sticks thru.

They'll also tend to be at spots where the circuit board gets flexed .... like where pots are soldered to the circuit board and then you turn the pots constantly flexing its' connections or where the jacks are soldered to the board and they get flexed by plugging and unplugging the cords and also where they have multi connectors between circuit boards inside the amp. Those connectors get flexed by the weight of the cables bouncing around as you move the amp.

BTW ..... any of those connectors inside the amp could concievably just need reseating. You unplug them ..... maybe use a little DeOxit to clean them and replug them.

IF you find any bad solder joints the fix is easy ...... reheat the joint ...... I typically add a tiny bit of solder to it but some don't.
 
At this point it's just a guessing game so go ahead and change the tubes. To figure out what the problem is you'll have to figure out what it isn't
 
Indeed..Any suggestions on which ones should I get, I want to change all of them for less than 110$.
 
If you leave the amp on for ahwile until it fully heats up...does the noise fade away?

What part of the country are you in, and is the amp ice cold when you power it up? It could be condensation...small amounts could make things arc/crackle until it dries out from the warmth.

Also...don't just exercise the tubes and put them back. Get some deoxidizer solution, like other's have mentioned...and using a Q-Tip, rub it on the tube's pins before you put them back into the amp...and THEN exercise the tubes a few times in/out.
Same with all the jacks...and if you have the jacks with the additional grounding leaf spring...that's often a common spot that connections are broken by oxidation.
 
You must log in or register to reply here.
Back
Top