Left channel not working, Right channel is on the left ear

[Pisti]

Hi,

I recently bought the Bottlehead Crack with the speedball prebuilt (was in use for about 2 years). When I first tested the Crack, the left channel was not working - even more strange is that the right channel is on the left ear. The guy where I bought it said it worked fine for him although he admitted that he could have damaged the Crack while packing or the Crack could have been damaged while on transport. I first checked the source and the cable but these were fine (switched the channels). I looked under the hood and found that the grounding (?) of the RCA jacks was not soldered anymore. I resoldered it but still the same result. Could this unsoldered connection harmed the Crack when I first turned it on? Do you guys have any other ideas what the problem could be?

I have a multimeter (although a very cheap one) and a soldering iron, but I am not very good at it (that's why I already bought it prebuilt). Nonetheless I would like to save the seller from taking it back and sending it back again so you guys are my last hope!

Thanks

 

[Doc B]

You will need to use the manual to go through the amp and test voltages. Here's the place top look for how to start troubleshooting:

http://www.bottlehead.com/smf/index.php/topic,1667.0.html

 

[Pisti]

The previous owner did not send me the manual yet, but he said he will soon.
There is also humming on the defect channel.
I did some more testing with different tubes, and slightly adjusted the input tube a bit. I heard some crackle on the defect channel and for a short time the channel was working! But it only worked in an exact position, so I moved it by a tiny bit and the channel was not working as before. I couldn't reproduce this (at first I thought my HD650 got damaged so I tried them on a different amp, but they still work like charm) after replugging and retesting.
Can the pins of the input tube connector a problem? I looked on the inside and the white ring where the pins from the input tube are (numbered 1-8), some of them are a bit loose. I can push the ma bit in (in the direction to the tube). Could this be a problem?

Thanks

 

[Doc B]

Yes, the previous owner may have removed and replaced tubes often. This can eventually stretch the metal sleeves in the socket. You can take a very small screwdriver and squeeze them closed a bit right at the top. Buffing the pins of the tube with a scotchbrite pad might help too.

 

[Pisti]

I am quite sure that this is the problem or at least part of it. I am able to get hear something through the channel, but only if I bend the tube slightly. I tried to get in there and squeeze the sockets from the top, but a few of them are covered quite well. Is there another way I could try to ensure the contact of the tube?

 

[earwaxxer]

Tube equipment can be a bit finicky. I know that when you buy something you expect it to work. You do have to get to know the kit though. Swapping tubes from left to right usually gives you a clue as to where to start. Frequently there is a problem with a tube (they can be delicate). I dont take my tubes in and out very often if I can help it, so that they dont degas etc. Dont give up on it! You will get it to work, and you may just become one of us (that may not be a good thing) ;D

 

[Laudanum]

"I looked on the inside and the white ring where the pins from the input tube are (numbered 1-8), some of them are a bit loose. I can push the ma bit in (in the direction to the tube). Could this be a problem?"

Im not saying that the socket isnt a problem, Doc B would certainly know a heck of a lot more than me.  But, the tube socket contacts/tabs do float a bit.  They arent secured in the sockets with adhesive so it isnt abnormal to be able to slightly move them side to side and in and out just a little bit.  As long as the tube pins slide into the tube socket contacts with a solid connection, the slight movement of those tabs do not matter.    Definitely follow Doc B.'s advice, he is the master  ;D    But,  if that fails you may also want to check for a bad/intermittent connection (poor solder joint, or wire) on one or more of those tube socket solder tabs.  Or, as mentioned above,  possibly the tube itself.