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jayceebee · 11th Feb 2019, 5:29 pm

First checks I would make would be on the anode of the thyristor W703, no volts here would point to either X701 which is the thermistor mounted on the large mains filter choke below the PSU or W704 on the PSU itself being o/c. If you have volts on W703 anode check to see if the 25V rail is present on the PSU test point. No 25V rail was often caused by a dry joint on R704.

John.

11th Feb 2019, 5:29 pm	#3
jayceebee Heptode Join Date: Jun 2007 Location: Durham, County Durham, UK. Posts: 640	Re: Thorn 8500 19in with Mechanical Tuner First checks I would make would be on the anode of the thyristor W703, no volts here would point to either X701 which is the thermistor mounted on the large mains filter choke below the PSU or W704 on the PSU itself being o/c. If you have volts on W703 anode check to see if the 25V rail is present on the PSU test point. No 25V rail was often caused by a dry joint on R704. John.