Lee Jackson Metaltronix Amplifiers

[Coldgin]

I was wondering if anyone could help. My VL502 keeps blowing the mains fuse. I'm not even playing loud, but after about 10 minutes, the fuse blows. Any ideas what may be wrong? Thanks

[ClassX]

Coldgin,, welcome to the Lee Jackson amp forum,,

Can you give me a little more info about the history of the amp,,, is the amp new to you?? ,, Was it playing last week just fine and just started blowing fuses ,,,?

Are the fuses the correct ones for this unit ?? ,,, I have a VL-502 myself,,for comparison if need be,,,,,

Are you using a 16ohm cab/speaker,,, or at least a 8 ohm ,,?

Are the 2 main output tubes glowing red hot after 30 seconds to a 1 min after you turn it on,,??,,, or do they have a slight glow at the top and bottom of both tubes ,,,,???

If you feel comfortable about taking the chassis out of the cabinet ,,, inspect the board for any burn/dark spots where the molex connectors attach ,,,,,,also you may find fuses on the inside ,, check them ,,to be the correct ones,,,

Keep on aRockin',,,,,,,

[Coldgin]

Hey there ClassX. Thanks for the greeting.

I have had this amp for a couple of years now. I'm using a Marshall cab set at 16 ohms.
I haven't had any problems with the amp, other than the fact that it doesn't seem as loud as it used to be.

I am using the right fuse. I put a new one in and pulled the back off. I turned the power on, and the tubes seem to glow properly. An orange glow at the top and bottom of the tube. This is with the standby on.
When I hit the standby switch and go to full power, all of a sudden the centre of the tubes take on a bluish glow. The one on the left with the back facing me actually flickers on and off with a bluish glow.
It was also making a small bit of noise in time with the flickering tube.

Then after about 10 minutes of playing, the fuse pops.

[ClassX]

Coldgin,,,,Sounds like the power tubes are gone for sure,,,power tubes should never turn blue,,,,

Do you have any experience working on tube amps,,, If not ,,I suggest taking it to an amp tech,,,as these amps have a history of melting the molex connectors inside the chassis,,Lee Jackson makes the service kits to repair these,,, if need be,,,,,

If your real lucky ,,, buying a set of matched output tubes,, either a set of EL34's,, or a set of 6550's,, and then having the amp re-biased,,, will be all you need,,,I prefer the 6550's(American tone,,, Van Halen,,ect,, more open sounding at extreme volume levels),,, but the EL34's(British tone,,a little more squishy,,break up faster) are less expensive,,,

Again,,, I can't stress enough the importance of doing a visual inspection to the board inside the chassis before attempting to put new tubes in,,,

Keep on aRockin',,,,,

[Coldgin]

I'm running el34's right now. I did notice that one of them has a black spot about the size of a dime and the glass.

I am familiar with the molex problem on these amps. I checked it out and there is no melting. There is a small brown burn mark on one connector on one pin only. Doesn't look too serious, but maybe I'll hard wire it anyways.

I prefer 6550's as well. I only use them on special occasions because of the cost. I keep the el's in there for practice and whatnot.

Maybe I'll go get another set of el's and put them in to see what happens before I burn out my 6550's. I hope its that simple. Thanks

[BM]

regarding BIAS, these amp self bias, so you can get some cheap EL's or 6550 and install them, let the amp idle for 20 minutes then try it...if it solves the problem then you can invest in some better tubes, Lee like's JJ's , Electro Harmoix and Mullards...but it is a personal decision,

I have herd that these are great sounding tubes :
SED Winged "C"
http://thetubestore.com/svetlana.html