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Pete_kaye · 3rd Sep 2017, 12:47 pm

I have recently bought a tired Mk2 version with following valves:- 6BE6, 6BA6,6BW6, 6AT6, and 6X5GT. Originally it worked, albeit quietly. A replacement rectifier and output valve brought the volume back and the voltages all about right. Any remaining wax caps have been replaced . However, there is an intermittent fault. After a few minutes, the volume drops suddenly but still OK to listen to on strong stations. Occasionally, the volume comes back temporarily. Various checks have shown the AGC voltage on V3 changes a little when this drop occurs . From -.04 to +.08. Would this be the likely cause?

My question is which components are likely to fail in this way? It takes about 30 mins before it has cooled down enough to return to the correct volume.

3rd Sep 2017, 12:47 pm	#1
Pete_kaye Octode Join Date: Jun 2005 Location: Sheffield, South Yorkshire, UK. Posts: 1,227	Toaster FB10 elusive fault I have recently bought a tired Mk2 version with following valves:- 6BE6, 6BA6,6BW6, 6AT6, and 6X5GT. Originally it worked, albeit quietly. A replacement rectifier and output valve brought the volume back and the voltages all about right. Any remaining wax caps have been replaced . However, there is an intermittent fault. After a few minutes, the volume drops suddenly but still OK to listen to on strong stations. Occasionally, the volume comes back temporarily. Various checks have shown the AGC voltage on V3 changes a little when this drop occurs . From -.04 to +.08. Would this be the likely cause? My question is which components are likely to fail in this way? It takes about 30 mins before it has cooled down enough to return to the correct volume.