Newcomer with questions

[Heckler45]

First I'd like to say hi.  This site seems like it is a wealth of info.  Thanks in advance.  Now down to the nitty gritty, I have a Moog Lab Series L7 (309A) and I need some help.  For those unfamiliar it has 2 channels.  The 1st is a clean channel, the 2nd offers clean, reverb, frequency and midrange.  The 1st channel is working great, the 2nd channel is not working.  All I can get from the 2nd channel is the sound of the frequncy adjuster.  I plug in the guitar and nothing.  The only way I get any sound from the second channel is when I turn the volume knob past 5 and the midrange is set to 0, it is at this point that I can hear the sound of the frequency pitch which changes pitch as I turn the frequency knob.  I found a bad solder joint on the input of the 2nd channel and fixed it but still no go.  Just so you know it makes this noise with or without the guitar plugged in.  Any ideas?

Thanks in advance,
-Dave

[Enzo]

So you have some bad part of failed connection in that preamp channel.

Do a search on this forum for Lab Series, and also specifically the L7.  You may find some insights, and I think we have posted the schematics of these.

As to why there is no signal, apply a steady good signal to the input and trace it through the amp.

[Heckler45]

Enzo thanksfor the heads up.   I'm going to poke around it again today to see if I can find any other bad solder joints.  I have the schematics but they aren't doing me much good as I haven't used a those skills since high school.  My brother is an elec. eng. so when he gets back in town I will hopefully have some help from him. 

When you say to apply a steady siganl, what would you suggest for that, perhaps hooking it to a stereo through the headphone jack?  Would the best way to trace it be to follow the printed pattern on the circuit board starting at the input jacks and working away from there?  Sorry, as I said I have not done much electronic work since high school 15 years ago, so I'm trying to regain any skills I had, and hopefully develope more.

[Heckler45]

I appreciate the assistance thus far, thank you.  I have decided however that this is over my head for the repairs due to out of practice skills and lack of proper equipment.  Luckily for me, I found out today that British Audio Sevices is 10-15 miles from my house.  I've heard they are excellent.  Think I'll put them to the test.  By the way for anyone near Ohio, or if you may have questions on Lab Series Amps try Empirical Sound they are on the web.  Called and talked to a tech today who was very knowledgable on the Lab Series Amps.  Please note that I am not afiliated with either of these companies just trying to pass along some helpful info.  Hopefully I will get my L7 in ater the holidays for the repair.  I'll keep you all posted so others who may have the same issue can learn from this.

Thanks again,
-Dave