Music only playing through one ear

[cayoung05]

Thanks PB, really appreciate your help. I'll give your suggestions a try tomorrow and tell you what I find

 

[STURMJ]

Also make certain that you have a volume pot, and not a balance pot.  Turn the pot to the halfway point and recheck both channels.  This is a fairly common mistake, either you ordered the wrong pot (almost happened to me once) or they sent you the wrong pot.

 

[Paul Birkeland]

Also make certain that you have a volume pot, and not a balance pot.  Turn the pot to the halfway point and recheck both channels.  This is a fairly common mistake, either you ordered the wrong pot (almost happened to me once) or they sent you the wrong pot.

Wow, that would be frustrating! It must've taken you a while to figure that one out.  The Alps Blue MN taper balance pot would indeed kill one channel for most of the useful rotation of the other.

 

[cayoung05]

I got another 12U7, but the buzzing in the right channel is still there, and i can't hear anything through that side unless the volume is very very low. Check the resistance, everything is checking out. Checked the voltages, everything is receiving power and none of the voltages seem irregular at A1-A9.

Sturmj, thanks for the suggestion. I checked that too, but I don't think that's the issue. resistance at both channels were the same as  when the volume was turned all the way down

Any other suggestions I can try?

 

[STURMJ]

Fortunately my near mistake was noticed Just before placing a order.  I clicked the next to last click on a order and my brain said did that say balance? and it did.  Luckily I still could change the order.

 

[grufti]

Have you plugged your headphones into another amp recently to make sure that your headphone cable and/or your headphones are OK?

 

[cayoung05]

Hey guys,

Sorry to bring back an old thread but I'm still having the same problems with the right channel cutting out. Whenever I resolder all the joints, both channels will work perfectly the first time I turn it on. But after I power down and turn the crack back on, music won't play through the right channel.

-I've replaced both tubes and these aren't the issue
-both red LED lights are getting power
-Ive checked the solder around the center pins of the RCA jacks and it doesn't appear to be shorting
-headphones (sennheiser 650s) work when I plug into other devices

Anyone have any other suggestions I could try? I'm running out of ideas. Thanks,

 

[Laudanum]

Heres what I would try, but mind you, Im not nearly as tech savvy as most of these folks.  Turn chassis plate upside down, keep hands, pets and kiddies clear.  Poke around with a non conductive probe ... wooden chopstick or small diameter dowel rod works well.  Not very technical but this is actually referred to as a chopstick test.  No kidding.  Just probe/poke/tap around the rca jack, volume pot, headphone jack and the associated wires and just about anywhere else if those components dont show the issue.  You can do this when the right channel is working to try and get it to quit or generate noise or when it's out trying to get it to come back to life, even if just for a second.  Could be as simple as a cold/poor solder joint, or wire broken underneath the insulation.  This "test" can often point you in the right direction, or right to the source when you have an intermittent connection/problem.  The good news is that there isnt much that can go wrong with the amp and since you built it, you can fix it.  Just have to find it first.  Stay persistent and again, be careful when poking around, keep bare fingers clear.

 

[Paul Birkeland]

When a channel cuts out, this should be accompanied by voltage(s) that aren't correct.

Recheck the voltages once the channel has cut out, then report back.

-PB

 

[cayoung05]

Laudanum and PB,

Thank you very much for your help. I measured voltages and everything seemed fine (I can post it later if needed). Then, I poked around with a wooden chopstick. I found that when i put pressure on the potentiometer tab that the right channel wire was attached to, I could hear both channels. So i cut the wire, reconnected, resoldered, and pushed the tab in a little. So far, so good, I can hear from both channels. Thanks again for your help, it's amazing something so small could be the source of problems!

 

[Laudanum]

It's great in those fairly rare instances when I can actually help and my pleasure to do so 
Hopefully it's a permanent fix.  Worst case, replacing the pot isnt too much of a PITA.