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Old 8th Dec 2018, 8:13 pm   #1
12jslater
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Default Roberts M5A mystery wires?

I have just started work on a Roberts m5a and there are three leads which should connect to a component but what? On the data sheet it doesn't show a component in its place?

Thank you
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Old 8th Dec 2018, 9:04 pm   #2
ms660
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Default Re: Roberts M5A mystery wires?

Are the red (?) and yellow wires connected to anything? If so where about in the circuit.

Lawrence.
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Old 8th Dec 2018, 10:19 pm   #3
12jslater
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Default Re: Roberts M5A mystery wires?

Both wires go to a tab on the chassis
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Old 9th Dec 2018, 12:37 pm   #4
ms660
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Default Re: Roberts M5A mystery wires?

What valves are fitted in your receiver?

Lawrence.
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Old 9th Dec 2018, 2:31 pm   #5
12jslater
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Default Re: Roberts M5A mystery wires?

The valves are 6f6g, unknown, vr55, Ech 35, vr55
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Old 9th Dec 2018, 2:37 pm   #6
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Default Re: Roberts M5A mystery wires?

Yes, I thought they might be octals, the service data shows side contact types.

EDIT: That valve line up doesn't make sense to me.

Lawrence.

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Old 9th Dec 2018, 2:44 pm   #7
12jslater
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Default Re: Roberts M5A mystery wires?

Any hope of me finding any data on this set?
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Old 9th Dec 2018, 3:50 pm   #8
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Default Re: Roberts M5A mystery wires?

This receiver gives me the feeling that it might have been got at, the mystery wires might have gone to the HT reservoir and filter electrolytics, so far as I can make out from the Trader sheet data that tag strip in your photo is a connecting point for the HT choke to the rest of the circuit, the tag the yellow is connected to I'm guessing is the feed from the rectifier, the tag that the red is connected to being the fully filtered output, one of the wires from the audio output transformer would be connected to the tag the red wire is connected to and the other wire from the audio output transformer would be connected to the anode of the audio output valve via the 100 ohm anode stopper resistor.

Lawrence.
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Old 9th Dec 2018, 4:32 pm   #9
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Default Re: Roberts M5A mystery wires?

In case you haven't seen it there was this earlier post from a member with an M5A with the later P5A valve line up
Steve.

https://www.vintage-radio.net/forum/...ad.php?t=55816
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Old 9th Dec 2018, 5:25 pm   #10
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Default Re: Roberts M5A mystery wires?

It looks like someone has cut into the wiring harness, added something, then removed it again. You'll need to trace the wires and reinstate them. There doesn't appear to be anything missing.
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Old 9th Dec 2018, 5:54 pm   #11
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Default Re: Roberts M5A mystery wires?

i suggest you post some much better pictures so we can give some advice. The pictures need to cover all of the underside wiring.
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Old 9th Dec 2018, 11:02 pm   #12
12jslater
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Default Re: Roberts M5A mystery wires?

Here are the wires and the tags they are connected too.
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