No Sound, Blue Glow... How'd this happen?!?

[otokomae]

OK, I have a Fender Supersonic that has gone from working fine to freaking out in mere minutes, and I can't find the cause!

All I did was change the tubes, set the bias for the new tubes, and when I put it back together there was no sound! Also, the tubes have started glowing blue, and I noticed that the jewel light, which used to come on dim and sort of go "in and out" while playing, is now on FULL and BRIGHT from the moment I switch the power on! I've tried changing to other, confirmed working power tubes, changed out the PI driver, and have the chassis open now, looking all through it for anything that might have burned out, but I can't find anything!

Can anyone offer me any help here, or possibly give me any idea where to start looking?

Thanks in advance!

[TD_Madden]

speakers plugged-in?

[otokomae]

Yep. Forgot to mention it, but the speaker is connected (it's a combo), and I also checked the cables to make sure they're working. The exact same guitar and cable had no problems through another amp, so I assume they're not the problem. I also plugged another amp into the combo's speaker, using the same cable, and it works fine. This one's a real mystery to me...

Oh btw, sorry for the double post; I didn't realize I'd done that! I'll see if I can get rid of the other one.

Thanks for the help! Any other thoughts?

[tubeswell]

bad/loose socket pin(s)/pin soldering? (Check socket pin lugs are soldered properly to the wires - no loose connections, and gently wriggle the lugs to make sure they are tightly attached to the tube pins (with power off/amp unplugged and caps drained of course)

[otokomae]

Yeah, that's along the lines of what I was thinking, actually... I guess I was just hoping that there might be some simpler solution that I wasn't thinking of. The solder joints on PIN 7 of tube V7 and PIN 2 of each of the power tubes in particular are a little "brown"... any ideas about which tubes/pins would be most likely to cause this problem?

[Don Moose]

Let's not overlook the simple version of a bad socket - one of the pin ... clips, i guess could have gotten bent out of shape getting the old tubes out or the new ones in.

No real idea how to check for that - maybe R.G.'s Tube Amp Debug Pages have something?

Hope this helps!

[Enzo]

Speaker is plugged in, but is it in the main speaker jack and not the extension speaker jack?

[otokomae]

Yeah, it's plugged into the main spkr jack. I didn't unplug it between the amp going from "fine" to "broken", so that shouldn't have been what caused it, but I did try plugging it into the ext spkr jack on the off chance that that might fix something, but no change. I also checked the fast-on's, and the speaker end of the cable is connected as well, and I've also tried plugging another amp into the combo's speaker, and it worked fine. I really do wish it were either the speaker or the speaker cable, since that would be an obvious fix, and it would just be a matter of replacing it (costly perhaps, but I could fix it right away and get back to playing!)

Thanks for the help guys! Seriously, this has really been a lot of help!

[Mars Amp Repair]

Hello,
The Supersonic's are fairly new, so I'd look for something you might have inadvertanly bumped loose or such.

Also, I'd say if you're seeing blue in the power tubes, then they have all the voltages they need to work...esp if the blue is being modulated by any sound input the amp.

Also, (don't do this for long) but can you hear sound coming directly from the output transformer when you play? Put your ear close to it while you play , if you can hear sound from the output transformer it ususally means everything is fine, but somehow the speakers are not getting connected to the transformer output, or perhaps the output transformer secondary (wires to speaker) leads in the amp are somehow shorted.

Look for any pinched wires coming from the output transormer or loose wires on the secondary. Is there a plug on the end of the output transformer & is it firmly in place. I've only seen a few of the SuperSonics, so I can't recall the geometry of it.

Just look closely at the secondary wiring from the output transformer. I guess Enzo already mentioned using the correct speaker jack.

glen

[txstrat]

Cause of the fact, the jewel is shining brighter than before. Did you check all the tubes heaters - are they all glowing? Maybe there was a bad solder joint that got loose when you changed the tubes. That might've had influence on the jewel.

Just a thought

Matt

[otokomae]

Found it!

Well, it seems like I've found the cause... after trying everything I could think of, I decided just to chopstick test every part of the amp from one end to the other. It turns out the solder joints on the hardwires that connect the 2 speaker output jacks were coming apart. I had an iPod running through the clean channel, and as soon as I started tapping those solder joints, the sound started coming back on! Seems like a lot of the solder joints are weak in this amp, to be honest; it's a great design, but I feel like I'll be fixing things on this amp for many years to come. For instance, the tube sockets seem to be made of some kind of plastic, so I can see replacing them in the future, but what makes that seems like such a chore is that there are 10 of them! But yeah, it's really a great design, and sounds as good as anything out there (especially in the $1,000 range) once you change out the tubes and set the bias; it was VERY cold from the factory, something I've seen a lot of people commenting on. It's just too bad that they came up with this great design, and then started cutting corners the minute it went into production! The transformers look solid at least; they're the size of 2 small toasters under there!

But yeah, it just looks like it came from the factory with some fragile solder joints that'll have to be redone. It's just a surprise that they came apart so easily, as the amp hasn't really been used that much, and this is only the 3rd time I've had to open it up to reset the bias and it's already falling apart!


Anyway, thanks a lot to everyone whose offered a suggestion so far, it's really been educational for me! Thanks guys!