Completed sex kit: No sound from right channel

[mpent]

Ok, understood. I am trying to tie this together in my head. So as of the last time I checked, I have voltages within range with the exception of A1, 9, B1 and 19 as indicated in my post on 6/19. Moreover, the issue of no sound in right channel unless I turn the gain to the max. Would this short you see be causing this?

[mpent]

Well, I finally got it working!!! Voltages and resistances all check out. The right channel issue was apparently a short in the gain. I think the reason why I thought I previously fixed this issue earlier in the build was because I had the SEX acting as a power amp with the gain all the way up with a preamp connected. Since removing the preamp and notwithstanding the tube that went bad, the issue was there all along. I insured not components were touching and double checked the wiring...resoldered a few joint and still no sound from right channel unless gain was set to max. Playing with the gain, I pushed it past the max gently and this seems to have corrected the issue. Not sure how really but I am getting good sound across the continuum of the gain. I hope I am good to go now. PB, thanks so much for bearing with me and for all your advice.

Michael

[mpent]

Hi all....so unfortunately I have to revive this thread.  The sound from my right channel is dropping again.  There seems to be a short somewhere and I am not certain how to address it.  Again, the problem is rectified when I turn the gain all the way up to the max...sound form the effected channel re-appears and I can attentuate across the continuum yet after listening for extended periods, the sound will once again drop out after a period of time.  Any advice? I am wondering if I could have a faulty volume pot?  Is that possible? 

Michael

[Doc B.]

Try exercising the pot by rotating it through it's entire range 20 or 30 times and see if the problem goes away.

[mpent]

Will do. Thanks.

Michael

[earwaxxer]

Try exercising the pot by rotating it through it's entire range 20 or 30 times and see if the problem goes away.

hummm....

[mpent]

Try exercising the pot by rotating it through it's entire range 20 or 30 times and see if the problem goes away.

Ok, so I heeded this suggestion but it did not solve the issue.  Again, when I turn the gain to max, sound will appear from right channel and will maintain across the continuum thereafter for an unspecified period of time.  If I listen for several hours, at some point the sound drops again from right channel. 

Moreover, after completing Reduction build and hooking that to SEX and turntable, no sound whatsoever from right channel.  Even if I turn the gain to max on SEX, no sound appears.  I hooked the Reduction up to another power amp in a separate system and it worked great so I think the problem persists with the SEX.

I am really at a loss.  Paul mentioned earlier in the thread that if there is a tiny level of hiss/hum with the gain all the way down in both speakers that the problem should be at the input or gain control.  I performed this test again and yes, with gain all the way down i do hear hiss in both channels...performed this with headphones as well to confirm. Any suggestions??

[Doc B.]

Have you gone through and re-soldered every joint on the right side circuit? It kind of sounds like an intermittent connection that is happening when parts in the amp run for a while, warm up, expand and maybe a connection that looks good opens up.

[mpent]

Yes, I did when I rewired the right circuit. I will go through it again though.....thanks.

[Grainger49]

This sounds just like a bad solder joint.  Do as Dan says and report back.  You don't need to add a lot of solder, that just makes "solder blobs" which are bad joints.  A tiny amount is fine. 

Just heat each joint with the soldering iron on the tube pin or terminal and touching the component lead/wire.  When it becomes liquid count to three and let it cool.

[mpent]

Unfortunately I need to resurrect this thread.  So after last post I went through and re-soldered every terminal and pin.  It seemed to have fixed the issue but only for a time. Yesterday, I turned the amp on and again, no sound from right channel.  If I turn the volume all the way up to max then I will get a very weak output from the right channel.  Went through visual inspection again...and resistance/voltage checks.  All resistances check out ok.  All voltages check out ok except:

Terminal 9, 19: Fluctuating reading 4-6mV; Fluctuating reading 7-17mV...the readings just fluctuate back and forth variably between these two numbers for each terminal respectively

Pin A1, B1: Same issue as above:  6-8mV and 10-12 mV respectively.

Any ideas?

Mike

[Paul Birkeland]

Hello Michael,

Can you try connecting the two middle lugs on the pot?

When you do this, do you get both channels, same as before, or other?

[mpent]

Ok, excuse my ignorance. How do I go about connecting the middle lugs?

[Paul Birkeland]

Temporarily solder the same piece of wire to each of them. (Or use a clip lead)

[mpent]

After soldering the wire in connecting the middle lugs of the pot, I get sound from both channels.  So what does this mean?  Should I leave the wire in there and consider the problem rectified?