Blues Junior: Tube location disaster

Billm

Member
Messages
574
Here's what happens when you put the EL84s where the 12AX7s belong, and vice versa:



A customer installed my basic mods kit and then reinstalled the tubes... and misremembered where they were supposed to go. The first power supply resistor and the two screen resistors burned before the fuse finally blew. The board below the PS resistor burned pretty much all the way through and the heat damaged one of the filter caps. Some traces on the back melted, too.

Here's the repaired board. I scraped and cleaned all the burnt areas, since the carbon is conductive, and cleaned up the smoke damage. I rebuilt the board under the resistor with fiberglass and resin, and crimp-mounted the new resistor off the board... just in case. I rebuilt the traces on the back, replaced a few components, and it's good as new.

I'm thinkin' maybe a 1.5A fuse instead of 2A would have saved the day.

 

lord preset

Member
Messages
881
Cool. I did that same stupid thing with a Pro Junior (it came shipped to me with the tubes out). The damage was nowhere near as extensive. Adam at Satellite Amps fixed it for me and affixed idiot proof labels next to the tube sockets.
 




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