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sobell1980 · 5th Dec 2017, 10:25 pm

Nailed it! Disconnected both heater wired each end (from the mains transformer and the socket). Traced the fault back to where there is a common joint for three connections, L18 HT, C65 and the heater supply of four volts. The heater wire connection was green and poor. Moving the joint with my meter on it gave a very intermittent high and low resistance. I've replaced the heater wires and she fired up and was singing away. A good repair to remember to check the voltages under load . It read 4 volts all day long with the valve removed till I tested it last night under load and this caused the voltage drop at c65. Next job to try to repair the other 6P65 valve and start to reassemble this set for Christmas delivery.
Many thanks for the encouragement and pushing me to find the fault and also for insisting I repair the uu6 heater pins.
Dave.

5th Dec 2017, 10:25 pm	#56
sobell1980 Octode Join Date: May 2011 Location: Bromyard, Herefordshire, UK. Posts: 1,241	Re: Murphy A188C repair. Nailed it! Disconnected both heater wired each end (from the mains transformer and the socket). Traced the fault back to where there is a common joint for three connections, L18 HT, C65 and the heater supply of four volts. The heater wire connection was green and poor. Moving the joint with my meter on it gave a very intermittent high and low resistance. I've replaced the heater wires and she fired up and was singing away. A good repair to remember to check the voltages under load . It read 4 volts all day long with the valve removed till I tested it last night under load and this caused the voltage drop at c65. Next job to try to repair the other 6P65 valve and start to reassemble this set for Christmas delivery. Many thanks for the encouragement and pushing me to find the fault and also for insisting I repair the uu6 heater pins. Dave.