Murphy A30C, help needed. - UK Vintage Radio Repair and Restoration Discussion Forum

G0HFCFrank · 30th Jul 2018, 4:19 pm

I collected a Murphy A30C yesterday and have been inspecting it. It has lost all four knobs; are the keepers threaded 6 or 8 BA or some other size? It has the original valves in place but I have top cap problems. the TC to the AC2PenDD is stuck in its flying lead and just a bit of bare wire sticking out the top of the valve. The ACVP1's TC lead is stuck firmly in place and I'm not sure of the best way to loosen it. All the top cap connectors have a bakelite shroud which I don't really want to sacrifice but I can't see any other way of freeing them. I've heard good things about these sets on here and I'd like to get this one into a wife-friendly condition. Any hints and tips would be greatly appreciated.
Thanks in advance,
Frank C.

Leon Crampin · 30th Jul 2018, 10:26 pm

Frank, the knobs are fixed with 4BA dome nuts (black) and shakeproof washers. The originals were bakelite, but painted metal nuts will match. They need to be very little more than finger tight.

The stuck top caps can be difficult. I would try to get some penetrant such as thin releasing fluid in there and gently work on them. A valve with a missing cap and the lead broken off can usually be repaired - make a Forum search. The valves for this set are easy to find anyway.

Try a general Forum search on the A30 as I've made a few comments in the past. It's a really nice understated design which works better than its modest specification would suggest. Put a 1A fuse in the plug. The 'speaker magnet is rather fine...

Leon.

MurphyNut · 31st Jul 2018, 10:21 am

Quote:

Originally Posted by G0HFCFrank

I've heard good things about these sets on here and I'd like to get this one into a wife-friendly condition. Any hints and tips would be greatly appreciated.
Thanks in advance,
Frank C.

They're lovely sets and have a particularly pleasing sound quality. I have the table version, just awaiting a mains transformer to get it going again. I would love a console, I guess it's only space that's holding me back!
Some people think they look rather austere, but if the cabinet is restored they can look really smart with their minimalist styling.
Regarding the missing fixing nuts /knobs have you tried the "wanted" section? I had a few of these little fixing nuts missing and a kind member was able to help me out.

ukcol · 31st Jul 2018, 10:37 am

Quote:

Originally Posted by Leon Crampin

Frank, the knobs are fixed with 4BA dome nuts (black) and shakeproof washers. The originals were bakelite, but painted metal nuts will match. They need to be very little more than finger tight.

Just a word of warning for general readers of this thread. Leon's suggestion to use metal dome nuts for the A30 is perfectly safe as the set uses an isolated chassis but some Murphy sets that use the same knobs, like the AD32, are live chassis and therefore it would not be safe to use metal dome nuts,

G0HFCFrank · 1st Aug 2018, 7:58 pm

Leon, Clive,
Thanks for your comments on my post, I remembered the trick of pressing down on the top cap and twisting it and this got the stuck one off. I have also dug the detached cap out of its shroud and am ready to refit it to the valve. Oh and the possibility of metal nuts on an AC/DC chassis is something to avoid Colin. I have AVOed out both speaker windings and the mains and output transformers, these all appear OK so I can start my search for knobs with a clear conscience. This set is high on my list of things to do when the bowling season ends next month. Watch this space!

Frank C.

30th Jul 2018, 4:19 pm	#1
G0HFCFrank Pentode Join Date: Oct 2011 Location: Oldham, Greater Manchester, UK. Posts: 167	Murphy A30C, help needed. I collected a Murphy A30C yesterday and have been inspecting it. It has lost all four knobs; are the keepers threaded 6 or 8 BA or some other size? It has the original valves in place but I have top cap problems. the TC to the AC2PenDD is stuck in its flying lead and just a bit of bare wire sticking out the top of the valve. The ACVP1's TC lead is stuck firmly in place and I'm not sure of the best way to loosen it. All the top cap connectors have a bakelite shroud which I don't really want to sacrifice but I can't see any other way of freeing them. I've heard good things about these sets on here and I'd like to get this one into a wife-friendly condition. Any hints and tips would be greatly appreciated. Thanks in advance, Frank C.

30th Jul 2018, 10:26 pm	#2
Leon Crampin Octode Join Date: Nov 2005 Location: Surrey, UK. Posts: 1,874	Re: Murphy A30C, help needed. Frank, the knobs are fixed with 4BA dome nuts (black) and shakeproof washers. The originals were bakelite, but painted metal nuts will match. They need to be very little more than finger tight. The stuck top caps can be difficult. I would try to get some penetrant such as thin releasing fluid in there and gently work on them. A valve with a missing cap and the lead broken off can usually be repaired - make a Forum search. The valves for this set are easy to find anyway. Try a general Forum search on the A30 as I've made a few comments in the past. It's a really nice understated design which works better than its modest specification would suggest. Put a 1A fuse in the plug. The 'speaker magnet is rather fine... Leon.

1st Aug 2018, 7:58 pm	#5
G0HFCFrank Pentode Join Date: Oct 2011 Location: Oldham, Greater Manchester, UK. Posts: 167	Re: Murphy A30C, help needed. Leon, Clive, Thanks for your comments on my post, I remembered the trick of pressing down on the top cap and twisting it and this got the stuck one off. I have also dug the detached cap out of its shroud and am ready to refit it to the valve. Oh and the possibility of metal nuts on an AC/DC chassis is something to avoid Colin. I have AVOed out both speaker windings and the mains and output transformers, these all appear OK so I can start my search for knobs with a clear conscience. This set is high on my list of things to do when the bowling season ends next month. Watch this space! Frank C.