Gallien Krueger Backline 600

[hamhands]

Good morning(evening?),

After a few days off and on browsing this forum, I'm pretty sure you guys might be my best bet. After 15 years in the automotive industry, I've got a decent handle on component testing but when it comes to amplifiers/boards, I'm treading into new water here. Basically, what I'm trying to convey is, I'm competent with a meter. I've searched online, and this forum for a schematic of this amp and came up with nothing specific so far though that might be more user error than anything. Furthermore, this might not be the right place for what I'm looking to do either. I'd like a better handle on how to go about checking an amplifier, where to start and end. I feel like I have a decent foundation for learning this, and was hoping I'd run across someone here that wouldn't mind directing me.

I have an older Gallien Krueger Backline 600. It's blowing a fuse every time I turn the thing on. And it's instant. As soon as I feed it power, the fuse blows. For me to send this off for repair in my area, it would cost an arm and a leg, and it's more than what this amp is worth in my opinion. I've taken the amp out of the chassis and I see nothing burned, nothing visible with my eye that would say there's anything wrong but I'm sure, as with most any other component, issues are normally hidden from our eyes.

Here's the exact amp I have -Used Gallien-Krueger Backline 600 300W Bass Amp Head | Guitar Center


Here's what pops up when I locate this amp on that bmaps.com page. Clearly the pdf isn't available. http://bmamps.com/Schematics/Gallien..._Schematic.pdf

Again, I'm just looking for some guidance. Where to start(once I find a schematic, of course), and what to do to attempt to figure out what's going on.

Thanks!

Jamie

EDIT- I did email GK for an exact schematic. Hopefully will hear back soon.

[nickb]

Good morning(evening?),

After a few days off and on browsing this forum, I'm pretty sure you guys might be my best bet. After 15 years in the automotive industry, I've got a decent handle on component testing but when it comes to amplifiers/boards, I'm treading into new water here. Basically, what I'm trying to convey is, I'm competent with a meter. I've searched online, and this forum for a schematic of this amp and came up with nothing specific so far though that might be more user error than anything. Furthermore, this might not be the right place for what I'm looking to do either. I'd like a better handle on how to go about checking an amplifier, where to start and end. I feel like I have a decent foundation for learning this, and was hoping I'd run across someone here that wouldn't mind directing me.

I have an older Gallien Krueger Backline 600. It's blowing a fuse every time I turn the thing on. And it's instant. As soon as I feed it power, the fuse blows. For me to send this off for repair in my area, it would cost an arm and a leg, and it's more than what this amp is worth in my opinion. I've taken the amp out of the chassis and I see nothing burned, nothing visible with my eye that would say there's anything wrong but I'm sure, as with most any other component, issues are normally hidden from our eyes.

Here's the exact amp I have -Used Gallien-Krueger Backline 600 300W Bass Amp Head | Guitar Center


Here's what pops up when I locate this amp on that bmaps.com page. Clearly the pdf isn't available. http://bmamps.com/Schematics/Gallien..._Schematic.pdf

Again, I'm just looking for some guidance. Where to start(once I find a schematic, of course), and what to do to attempt to figure out what's going on.

Thanks!

Jamie

EDIT- I did email GK for an exact schematic. Hopefully will hear back soon.

Here you go Gallien-krueger_400RB-IV,_BL-600_(2005)_Power_Amp_Schematic.pdf

bmamps.com is my site. The story behind why I had to remove the schematics is history and but for the power of Google stitching together old files you'd never have known..

..anyway, you're probably looking at a power supply or power amp (blown output transistors) problem.

[Randall]

If there is a connector from the power supply to the main or power amp section, unplug it. If it still blows the fuse, it's a shorted power supply. If not, it's probably a shorted power transistor.

Look up dim bulb tester and build one, it will save you a lot of fuses with problems like this.