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Boater Sam · 5th Dec 2017, 6:40 am

There has to be a wire not connected. The 4v comes off the transformer to the valve filament, as it is a directly heated valve the cathode is the filament to all intents.one of the 4v wires also goes to L18 as this is the cathode connection of the valve to the HT line.
You have the Murphy official sheet?

The tiny numbers on the physical chassis layout Fig 2 are connection numbers, I'll put them in brackets.

So, you have 4 v AC on the transformer, (106 & 107) follow those 2 wires. They go to the 2 valve socket filament pins 1 & 8 (106 & 107)and ONE of them (106) also connects to L18 (106) and the same to the capacitor reservoir C65 (106)

OR are there are 2 wires on the same terminal of L18, 1 to the valve, 1 to the transformer? Or even 3, 1 to C65? Or 3 on the same tag of C65?

Either way the result is the same, the valve gets 4v AC to heat it (106 & 107) and the DC HT from the cathode (106) goes to C65 (106) and L18 (106) and on to the rest of the set from the other side of L18 (44)

So, unless the wiring has been changed or a wire broken off or a really bad soldered joint, it should work! You have all the bits that matter working, the valve, socket & the transformer.
I can't look at which way mine is wired, its 8000 miles away at the moment!

Follow the circuit diagram, the wires may take different routes but the result is the same connections, make the set agree and you are done, well done.

5th Dec 2017, 6:40 am	#47
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: Murphy A188C repair. There has to be a wire not connected. The 4v comes off the transformer to the valve filament, as it is a directly heated valve the cathode is the filament to all intents.one of the 4v wires also goes to L18 as this is the cathode connection of the valve to the HT line. You have the Murphy official sheet? The tiny numbers on the physical chassis layout Fig 2 are connection numbers, I'll put them in brackets. So, you have 4 v AC on the transformer, (106 & 107) follow those 2 wires. They go to the 2 valve socket filament pins 1 & 8 (106 & 107)and ONE of them (106) also connects to L18 (106) and the same to the capacitor reservoir C65 (106) OR are there are 2 wires on the same terminal of L18, 1 to the valve, 1 to the transformer? Or even 3, 1 to C65? Or 3 on the same tag of C65? Either way the result is the same, the valve gets 4v AC to heat it (106 & 107) and the DC HT from the cathode (106) goes to C65 (106) and L18 (106) and on to the rest of the set from the other side of L18 (44) So, unless the wiring has been changed or a wire broken off or a really bad soldered joint, it should work! You have all the bits that matter working, the valve, socket & the transformer. I can't look at which way mine is wired, its 8000 miles away at the moment! Follow the circuit diagram, the wires may take different routes but the result is the same connections, make the set agree and you are done, well done.