old super lead repair

martin g · Post by **martin g** » Tue Feb 22, 2005 6:07 pm

Hello I'm gonna to buy old super lead from 69-70' and I've got a question about changing tubes for JJ El34L, How to bias this amp which tube pin and what method. I've got a digital multimeter. What do you recommend me to check and change in super lead, what year could it be serial SL/10252? thanks for any advice

Flames1950 · Post by **Flames1950** » Tue Feb 22, 2005 7:14 pm

If that's the correct serial number it's older than '69. Both '69 and '70 would have had a letter "A" at the end of the serial number, with "B" getting skipped and '71 picking up "C" on the end.

Flames1950 · Post by **Flames1950** » Tue Feb 22, 2005 7:16 pm

I'm not sure what's up with that thing in the middle of the powr tube sockets, is that a small transformer or a relay?? Yikes.

Country Boy Shane · Post by **Country Boy Shane** » Tue Feb 22, 2005 9:56 pm

That does look awful fishy. What the hell is that?

Flames1950 · Post by **Flames1950** » Tue Feb 22, 2005 11:55 pm

Still, if the price is right get it and we can help you return it to its former glory.....

martin g · Post by **martin g** » Wed Feb 23, 2005 6:44 am

Thanks, Do you think that something's wrong with this amp? I send more pict. How about biasin how to bias this amp what should it be where could i check what tube pin, which method is the best cathode resist or transf.

Billy Batz · Post by **Billy Batz** » Wed Feb 23, 2005 8:44 am

martin g wrote:Thanks, Do you think that something's wrong with this amp? I send more pict. How about biasin how to bias this amp what should it be where could i check what tube pin, which method is the best cathode resist or transf.

No. Nothing wrong with it. At least nothign that cant be easily fixed as long as all the major parts work. To bias with the cathode resistor method you need to install a 1ohm 2W resistor going from pin 8 to groung if there is none. Remove whatever wire is alread going from pin8 of each power tube socket to ground and replace with the 1ohm resistor. Then you check the voltage accross it. Theres plenty of info about how to bias with these readings. Check out ampage.com.