My Crack is toast... again [Solved]

[Nick Tam]

Right so this time, right side channel pops occasionally and when the input tube is nudged. Any ideas?

[earwaxxer]

Nudging a tube is probably going to cause noise of some sort anyway. Problems with the sound otherwise?

[Grainger49]

If this is a new problem, it has been working well for a while, try FAQ #2.

Keep in mind, new sockets and tubes can sit around for years and collect surface corrosion before use.

Then go to checking solder joints.  I had one let go on my FP 2 from 10 years back.  It was good for 10 years then let go.  It can happen to anyone.

[Doc B.]

Dielectric grease should work OK if applied very sparingly.

[Nick Tam]

Okay solved it.

It wasn't even a bad solder joint, I think the problem has been there since I built it the first time; The two of the posts on the 9 pin socket of the right channel were loose had some wobble to begin with, all I did was apply solder to the base of the posts to fixate them to stop the wobble and the noise is gone.

Thanks guys.

[Laudanum]

The "wobble" is normal, you can get any one of those contacts to wobble when a tube isnt installed if you manipulate them.    The tube pin contacts/solder tabs arent exactly glued into the ceramic socket, they "float" for lack of a better word.  It allows for any slightly bent tube pins to still align in the contacts.    The wobble really doesnt matter because once the tube is in place, everything is cool as long as the actual tube pin contacts are tight around the pins.  The real problem may be a couple loose tube pin contacts themselves (a contact/contacts inside the ceramic not making tight contact around the tube pin/pins).   Your fix may be temporary ... by adding solder to keep the tube contact from moving, you may be covering up the real cause of the noise.  Atleast for the time being.  

If you have any more problems .... you can unplug the amp, remove the tubes, and try tightening the actual tube pin contacts that you think are problematic.  Something small enough to squeeze down the hole in the socket and wedge between the ceramic wall and the metal contact, carefully applying pressure to try and close it further so it will make tigher contact on the tube pin.   Ive done this before with a vintage amp and still works to this day.   You also may want to order a spare socket just to have on hand in case it ultimately needs replacing.

But hey, if it's working now then it aint broke so dont fix it.  Besides, I could be totally wrong.  It's been know to happen often enough  

[Nick Tam]

My tube is in fact tight in the socket, the contact posts slides in the ceramic socket when nudged so I thought the noise had something to do with it... otherwise I can swap out for the teflon socket as well but I REALLY CAN'T BE BOTHERED to touch the soldering iron again... oh well the pops is gone, hope the fix will last.

[Laudanum]

Yeah, like I said, if it aint broke, dont fix it.  I wouldnt sweat it as long as it stays quiet.       

Just some thoughts for future reference ... The tube would still fit tight in the socket if most of the contacts were tight.   But just one or two loose ones can cause problems and you wouldnt know it by going by how tight the tube seemed to feel in the socket.  Just pointing it out for something to consider in case you have the same problem in the future.  If you do, you can try what I listed in my prior post.  Also, dont rule out dirty contacts (and/or tube pins) first if you have noise issues that seem to be tube or socket related.   Uninstalling and reinstalling the tube in the socket several times can clean both the pins and the socket contacts.  You can also use some contact cleaner and one of those tiny dental brushes that get between the teeth to scrub the contacts.  Or even toothpicks and contact cleaner or 91% or better Isopropyl alcohol.

Anyway, glad to hear she's up and running once again.  Hope you are enjoying the amp.  I know I have been enjoying mine for a good clip over a year now.   Ive been listening to my old 600 ohm AKG K141's lately.  Got these back in the very early 80's.  I replaced the worn pads and elastics just after I built Crack but hadnt listened to them much until recently.   They bring back memories, they were my first decent pair of headphones and Im remembering the sound from back when and it's pretty cool.  They sound good, just a bit rolled off up top and the treble isnt quite natural.  But a blast to listen to.

Best.