Build Your Own Clone Message Board

Hi there.
I just "completed" an amp selector stereo fx router, and it is doing something strange. I am using it as an amp selector between Marshall class 5 and fender princeton

When I have a guitar plugged into input A, output A works for a second (way lower volume) and then fizzles out. Output B works fine. "Both" works for a second and the output A fizzles out.

When I switch the amps I get the same effect so it is not a function of the amps. Isolation seems to work fine, LEDS working fine, I cleanly soldered and now have reflowed and checked, everything in place, same effect. Here are some pictures, I cannot see any obvious problems, but the fact that it works and then fizzles out makes me wonder if some part is failing?

trying to get a new camera but let me know if there is something else to take a pic of.

Thank you! really enjoying the builds.

My first comment would be that there is not enough solder on the jack tabs. You should fill those holes and see if that helps. Next, it would be helpful to see the solder side of the PCB...

Welcome to the forum swantonio!

Yep, what mmarsh said. Here's a clean example of what your jack soldering should look like:


It's a little hard to imagine that the jacks are causing your symptom (though you still need to resolder them), so before doing that, I recommend taking the pcb back out of the enclosure and redoing the solder joints on the back of pcb again. Take some photos while you're at it. And it's not likely a bad component, it's more likely a short or bad connection.

Also, have a look a Stephen's tips and try to make your joints look like his: http://www.buildyourownclone.com/board/viewtopic.php?f=9&t=6401

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Thanks guys I will re-read the soldering tips, I have done a lot of soldering before but not with these types of circuits. I usuall err on the side of less solder, but going to redo the jacks and fill in the holes.

I was reluctant to remove the board from the box because I used bezels and you have to solder the LEDS last after assembly that way or else you cant push them in to the bezels! I just learned to not cut the LED leads until after I check it for that reason alone now I gotta buy some more LEDS. whoops.

I guess I thought it might be a part because it works for a second and then cuts in a fade. like effect is like the amp is being unplugged almost. I checked the switch and everything else looks clean to me, there is a little bit of rosin bleed from when I desoldered but I think it is really pretty clean.
One other thing I noticed in checking it was that when I had something plugged into input b (second guitar in this case) it really distorted. not sure that isn't a part? like an op amp or something?

thank you for the quick response! really appreciated, I am not frustrated by this at all it's really fun to try and figure out these issues for me. especially with the help/ just has to be something simple. I'll start with the jacks.

Of course I am always a proponent of human error and learning! it's probably me.

One other thing you might try is to swapping the two TL072's at the bottom left of the PCB. I *think* one feeds the A channel and the other the B channel, see if that makes a difference.

Most of your soldering looks good, but some of the IC socket joints are starved for solder. Make sure they all have enough. And fill those holes where the transformer tabs insert with solder too; you need to lock those down so they don't wiggle and stress the other joints over time. Also, finish filling the solder holes from the back for the DC jack now that it's set in place.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Hi guys thanks for all the advice. It works!
Let me tell you what I did.
First I tried filling in the holes entirely for the jacks and for the 9V plug. Then I reheated and soldered the joints for the IC sockets. tried it out, no difference. same problem. Tried switching the TL072s, no difference.

OK, so then I tired desoldering and re-soldering the switches and connections the the PCB no difference.

Then I tried stepping away from it for a few hours good suggestion in the soldering tips

Then I came back to it, reheated every point on the back of the PCB. No difference
Then, I heated all the resistor and reachable cap points on the top of the board. It works!
Then I desoldered and put in new LEDS (for the bezels, impossible to set the old ones back in there.) but LEDS were cheap.

Thanks for all the suggestions, of course the newbie blames the part. But, it seems the only part the was defective was my hand the first time around soldering the resistors and caps. they looked so clean but I guess maybe one of them wasn't good. Anyway, with a bit of patience it worked out fine really the hardest part was resetting the switches because I gave myself short leads.
Thanks guys

Nice job!

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MasterDelayer/Reverbrador/Ampaholic/TopJacker