Hi all. I picked up a Gibson Crestline Skylark off the e-auction site a month ago. No speaker or back panel, but all of the tubes intact. I threw in a 10" alnico Oxford, and it's a real hummer. I pulled out the chassis to do a cap-job, and the circuit doesn't look like the schematic I have for a Crestline Skylark. Looks more like an Epi EA-50T minus the tremolo. The circuit is certainly original and unmolested, and the pots/trannies date it to 1964. I know that 1964 was a transition year for the Skylark, and the Epiphone amps were comming out of the same plant as the Gibsons, but is this a normal deviation for these amps? Admittedly this is the first Gibson I've worked on, so I must digress to the experience of the gentlemen here on this forum.
Another interesting note is that after I replaced and formed all of the electrolytics, input #2 really buzzed. Upon looking I found that the star ground for the entire amp, including the filter caps, terminated at the ground lug of the #2 input jack. Relocating the star ground point to one of the power transformer bolts fixed my buzz. Was this a common grounding scheme on these early Gibsons? All in all I gotta say that this amp is pretty cool. I swapped out the 6AQ5's with some JAN 6005's and it really cooks when dimed. As always, I appreciate your input.
-PD
Another interesting note is that after I replaced and formed all of the electrolytics, input #2 really buzzed. Upon looking I found that the star ground for the entire amp, including the filter caps, terminated at the ground lug of the #2 input jack. Relocating the star ground point to one of the power transformer bolts fixed my buzz. Was this a common grounding scheme on these early Gibsons? All in all I gotta say that this amp is pretty cool. I swapped out the 6AQ5's with some JAN 6005's and it really cooks when dimed. As always, I appreciate your input.
-PD
