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sexton_mallard · 8th Jun 2020, 10:41 pm

The unintended abuse of the UL84 has resulted to minimum hum but the grid is back up to +2 volts so the set will not be used until a replacement arrives. The stopper resistor was replaced and the grid leak resistor which has gone up to 550K will be replaced with a 330K as suggested. I confirmed the grid leak was in the valve by pulling out the valve and bridging the heater pin sockets with a few wirewound resistors paralleled to give about 90 ohms to complete the heater chain. The voltage on the grid socket was virtually nil to 20 millivolts.

8th Jun 2020, 10:41 pm	#18
sexton_mallard Heptode Join Date: Sep 2013 Location: Ellesmere, Shropshire, UK & Co. Cork, Ireland. Posts: 502	Re: Ferguson 384U (Finesse) The unintended abuse of the UL84 has resulted to minimum hum but the grid is back up to +2 volts so the set will not be used until a replacement arrives. The stopper resistor was replaced and the grid leak resistor which has gone up to 550K will be replaced with a 330K as suggested. I confirmed the grid leak was in the valve by pulling out the valve and bridging the heater pin sockets with a few wirewound resistors paralleled to give about 90 ohms to complete the heater chain. The voltage on the grid socket was virtually nil to 20 millivolts. __________________ Dom Less snakes...more ladders! Last edited by sexton_mallard; 8th Jun 2020 at 10:56 pm.