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Problem with Q-tron

AdamJames306

AdamJames306

Sep 7, 2008
117
4
Bed-Stuy, Brooklyn
#1
Hey guys, I've got an old Q-tron pedal, bought it probably 8-10 years ago. I've long since lost the adaptor and haven't used the pedal in years. I got an itch to try it out again, bought a replacement adapter on eBay, and plugged it in yesterday. The problem is, the signal is really REALLY weak. It's pushing a signal, I can hear it, but I had to turn on my distortion and turn off my noise gate to even get close to producing a sound. Anybody know why this might be? The pedal could be underpowered, I suppose, but I bought a 24 volt adapter and the ad on eBay said it was for a Q-Tron. Possible bad connection in the pedal? Anyone?
 
#4
Really REALLY week? Like no filter sweeps at all? Is it cutting your volume significantly? What mode do you have it set to (LP, BP, etc etc,...I'm assuming you are experimenting with this,....but thought I'd ask anyway).

I had a Trap Steel Q-Tron for a moment and I was very underwhelmed by it. It seemed to be working properly and I had no volume loss,....but I seriously couldn't hear the filter sweeps at all in a band setting. Admittedly it may not have been the pedals fault,...but I was happy to ditch it anyway.
 
#5
AdamJames306 said:
It's a regular old Q-tron:

Electro-Harmonix Q-Tron

How would you adjust the polarity of a power supply?
Click to expand...

Polarity isn't something you adjust. I mean I think you can get an adapter that will reverse polarity,...but it's not something that a user can screw up beyond buying the wrong power supply.

If it's the wrong polarity though,...wouldn't the pedal not power up at all?
 
#6
Well, the replacement adaptor that I got from E-H a while back is rated at 24v DC output and 100mA. Mine is center positive, too. Hopefully your adaptor also runs at the right current and in the right direction. Sorry that I'm not a heavy electronics head, but I'll try to resist asking if you checked the air in the tires. If you get some signal that's actually affected, that makes me less suspicious of your physical connections.

Btw, this adaptor model # from E-H is: MKD-35240100

The other thing I'm thinking about is whether you get a normal strong signal going through your 'Tron with the pedal bypassed or if it's also weak that way?

Oh look ^^^, the real cavalry is here!!!
 
#7
warwick.hoy said:
Polarity isn't something you adjust. I mean I think you can get an adapter that will reverse polarity,...but it's not something that a user can screw up beyond buying the wrong power supply.

If it's the wrong polarity though,...wouldn't the pedal not power up at all?
Click to expand...

I have this thing going on in the back of my mind where I have actually seen a pedal do as the OP is describing with the wrong polarity, but I can't actually recall when, where or with what pedal. I'm not dead certain.

The supply should say what the polarity is. It should have a graphic that looks something like this:
- --(o-- +

If the plus is on the side of the half circle then it is wrong.
 
#8
There are audible filter sweeps, but the volume is significantly reduced. I'd say by 95%, and when the pedal is bypassed, there's no signal at all. I've played with all the settings, twiddled all the knows, switched all the switches. Same deal. I'll check to see what polarity the adapter is. Any other suggestions? Could it be something as simple as having to resolder a connection?
 
#9
Hmmm,...yeah it's hard for me to say and in reality you are going beyond my expertise in these things. If it turns out that the powersupply is right,...it could be anything along the lines of having a bad foot switch to there being a problem with an IC chip (no signal when bypassed).

The only possible other thing I could suggest trying is making sure you output your signal through the "Effect Out" not the "Direct Out". That's such a no brainer I feel like a douche even mentioning it (air in the tires?).
 
#10
AdamJames306 said:
There are audible filter sweeps, but the volume is significantly reduced. I'd say by 95%, and when the pedal is bypassed, there's no signal at all. I've played with all the settings, twiddled all the knows, switched all the switches. Same deal. I'll check to see what polarity the adapter is. Any other suggestions? Could it be something as simple as having to resolder a connection?
Click to expand...

Yes. I actually can't believe this didn't occur to me first. If your pedal is shorting to ground, it will significantly reduce the amount of signal getting through the pedal. An open might cause it, but far more likely a short to ground. Check your cables first, then check the pedal guts. Fortunately the guts of the old Qtron are vast and easy to work in.
 
#13
No signal when bypassed? Is it true bypass or buffered? I'm thinking the bypass switch may be going out. I don't know how the Qtron accepts power or if there's diodes in there to deal with a wrong supply (most pedals don't), but generally an incorrect supply will not work at all. I'd still suggest checking if the power supply is right, but my money's on the switch.

If you don't have one, buy a cheap multimeter, or borrow one. It would help to check the internal connections.
 
#14
Not sure if you figured this out...but I may have a possible solution. I have an old qtron+, and unless you run a patch cable from the output to the input of the patch (effectively completing the loop) my petal does the same thing. Apparently, on some models this is just how they work. If it isn't the qtron+ you have...this info may be irrellevent.
 

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