Scorpion Lead Amp - Cap Replacement

[Baldychris]

Hello!

I have a Scorpion Lead amp in need of attention. Signal is coming through, but at a very low level. There is distortion, but it sounds more like a fuzz box than pre-amp drive. As soon as you stop playing any notes, the noise floor rises in volume as though there's some kind of compression going on.

When I listened to the DI output at low gain, it sounded great! Good level, EQ and reverb worked as expected and it sounded clean. As soon as I started to turn up the gain, it squealed and went back to square one, even when turning the gain back down again.

I've listed all this in case anyone else gets the same symptoms, but there's at least one thing that's pretty obvious. One of the caps has half come off the board. I can't see which leg(s) are loose until I remove the chassis, but it's marked as C26.

Although this obviously needs sorting, I just wanted to ask if this component failing fits the symptoms. I'm a beginner and any kind of explanation as to what's actually happening to the signal in this case will help me learn.

I'm also confused by the schematic. Next to C26 it says "220" and "16V". Does this refer to capacitance and voltage? Because on the casing of the cap in my amp it says "25V" and "1000 microfarads". I've attached the schematic in case it helps:

Any help, as always, is much appreciated.

[Twist]

If you'll look at C25 on the schematic you'll see it's the same value. C26 and C25 should be the same value. The schematic says 220uf 16volt. You can use 1000uf 25volt caps. Those two caps help steady the voltage regulation by the two 16volt zeners. This is your pre amp voltage rails. Absolutely make sure you install them with the right polarity or you'll blow up a cap. I bet this fixes your problem.

[Twist]

Sorry !!! I meant 12 volt zeners.

[Amp Kat]

It has most likely been worked on before and the previous tech replaced it with the 1000uf caps. Obviously this is either a poorly designed circuit which is dissipating more heat than it's maximum rating or there is another component that is faulty causing it to get hot. increasing capacitance in SS is usually not a heat sensitive thing and adds more filtering which can be a good thing so some further testing may be required.

[Baldychris]

Thanks very much guys!

I'll replace the cap to start with and see if that fixes the immediate problem. Either way, I'll do some testing afterwards which I'll probably need help with. Expect more posts!