Murphy A362 capacitor question. - UK Vintage Radio Repair and Restoration Discussion Forum

Gabe001 · 1st Dec 2020, 8:59 pm

Hi,

Just a quick question about a Murphy a362 I'm currently working on.

It works on all bands already so I'm hoping this will be a bit more straightforward compared to the KB I've just finished (fingers crossed). Special thanks to Ken (tode) who has given me a few tips already. I've changed the wax capacitors and will do the hunts next. They're in awkward positions, I think that whoever designed the layout of the components had a grudge.

In view of the very odd (to me) autotransformer and earthing arrangements, can I verify which capacitors need to be type Y before I do my online ordering? I think it's C14 only (AM aerial socket) as the earth socket is earthed (mains earth) and the FM sockets seem isolated, buy would just like to be doubly sure

I am using the trader sheet 1377 from the BVWS CD.

Thanks in advance
Gabriel

Simon Gittins · 1st Dec 2020, 9:45 pm

The earthing arrangements do look odd! As I read the diagram, the earth core of the mains lead is taken to the earth socket as a flying lead. I think that C9 (between chassis and the earth socket) should be Class Y as well as C14.

Gabe001 · 2nd Dec 2020, 7:15 am

Thank you.
I would have said c14 too, but the socket it earthed directly to mains earth which means that there should be no risk to user if c14 leaks. At worse it'll trip the RCD. I stand corrected if my understanding is wrong.
Still no harm in using a type y I suppose.

Gabriel

Kentode · 2nd Dec 2020, 10:56 am

I'm referring to the Murphy service manual, also from the DVD, apologies for the confusion!

The snippet below shows the whereabouts of the two caps l added.

Gabe001 · 2nd Dec 2020, 12:34 pm

Thanks Ken. I think we're all pretty much thinking along the same lines.

1st Dec 2020, 8:59 pm	#1
Gabe001 Octode Join Date: Oct 2019 Location: Stockport, Greater Manchester, UK. Posts: 1,639	Murphy A362 capacitor question. Hi, Just a quick question about a Murphy a362 I'm currently working on. It works on all bands already so I'm hoping this will be a bit more straightforward compared to the KB I've just finished (fingers crossed). Special thanks to Ken (tode) who has given me a few tips already. I've changed the wax capacitors and will do the hunts next. They're in awkward positions, I think that whoever designed the layout of the components had a grudge. In view of the very odd (to me) autotransformer and earthing arrangements, can I verify which capacitors need to be type Y before I do my online ordering? I think it's C14 only (AM aerial socket) as the earth socket is earthed (mains earth) and the FM sockets seem isolated, buy would just like to be doubly sure I am using the trader sheet 1377 from the BVWS CD. Thanks in advance Gabriel

1st Dec 2020, 9:45 pm	#2
Simon Gittins Heptode Join Date: Jan 2006 Location: Cornwall, UK. Posts: 506	Re: Murphy A362 capacitor question. The earthing arrangements do look odd! As I read the diagram, the earth core of the mains lead is taken to the earth socket as a flying lead. I think that C9 (between chassis and the earth socket) should be Class Y as well as C14.

2nd Dec 2020, 7:15 am	#3
Gabe001 Octode Join Date: Oct 2019 Location: Stockport, Greater Manchester, UK. Posts: 1,639	Re: Murphy A362 capacitor question. Thank you. I would have said c14 too, but the socket it earthed directly to mains earth which means that there should be no risk to user if c14 leaks. At worse it'll trip the RCD. I stand corrected if my understanding is wrong. Still no harm in using a type y I suppose. Gabriel Last edited by Gabe001; 2nd Dec 2020 at 7:36 am.

2nd Dec 2020, 10:56 am	#4
Kentode Octode Join Date: Mar 2015 Location: Yorkshire, England. Posts: 1,301	Re: Murphy A362 capacitor question. I'm referring to the Murphy service manual, also from the DVD, apologies for the confusion! The snippet below shows the whereabouts of the two caps l added. Attached Thumbnails __________________ Regards, Ken. BVWS member

2nd Dec 2020, 12:34 pm	#5
Gabe001 Octode Join Date: Oct 2019 Location: Stockport, Greater Manchester, UK. Posts: 1,639	Re: Murphy A362 capacitor question. Thanks Ken. I think we're all pretty much thinking along the same lines.