16th Aug 2022, 7:20 pm | #1 |
Tetrode
Join Date: Nov 2014
Location: Isle of Man
Posts: 86
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Murphy A72
Found this locally. It looks like it will keep me busy this autumn/winter. The cabinet has plenty of old woodworm exit holes and scratches. The speaker cloth is ripped and the rim surround is damaged. The speaker cone has a hole in it and that is before I have even looked at the electronics.
The seller claimed he plugged it in and it made a "noise". He is a braver man than me looking at the state of the mains cord, of course with the obligatory 13A fuse and loose earth screw Obviously it won't be powered again until the usual suspects are checked. Not sure what is going on with the replacement valve either. Will be back for help when I get around to it, as my valve work is still limited, preferring early transistors. Dave |
16th Aug 2022, 7:21 pm | #2 |
Tetrode
Join Date: Nov 2014
Location: Isle of Man
Posts: 86
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Re: Murphy A72
Few more photos
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16th Aug 2022, 8:51 pm | #3 |
Nonode
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 2,369
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Re: Murphy A72
Hi Dave, these are nice sets and sound very good. I had one a few years ago, but mine was missing the station preselector with push-buttons that is present in yours. You might have discovered that the peculiar valve arrangement ought to be an HL42DD. It has been substituted with an earlier TDD4 using a valve base adaptor. It will probably work OK since the operating characteristics of the 2 valves are broadly similar, except for the grid bias where the TDD4 wants approx -7v whereas the HL42DD only -1.25v. Check if the cathode resistor has been changed from the original which you can find from the service data here https://www.service-data.com/search....&search=Search if you haven't already got it. Best of luck! Jerry
P.S. The set looks like it has had a hard life so before you do much else check the windings on the mains transformer, output transformer and speaker field coil since rewinds or replacements can be expensive. Last edited by cathoderay57; 16th Aug 2022 at 9:02 pm. |
16th Aug 2022, 9:54 pm | #4 |
Tetrode
Join Date: Nov 2014
Location: Isle of Man
Posts: 86
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Re: Murphy A72
Thanks Jerry
I'll check the transformers and field coil before doing anything else. Appreciate the valve advice, Dave |
17th Aug 2022, 7:46 am | #5 |
Heptode
Join Date: Apr 2016
Location: Croxley Green, Hertfordshire, UK.
Posts: 979
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Re: Murphy A72
I have one of these and it's a lovely sounding and striking looking set, Luckily mine was straight forward to fix mainly just the capacitors. Just note when removing the chassis it's all connected to the tuning scale drum and can be a bit awkward. I see you have the remote control, they are quite rare, nice find!
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Clive |
17th Aug 2022, 8:08 am | #6 |
Tetrode
Join Date: Nov 2014
Location: Isle of Man
Posts: 86
|
Re: Murphy A72
Thanks Clive, looking forward to ( hopefully ) hearing mine. Yes I was wondering about the chassis to tuning scale cable, will study carefully before removing anything.
Is mine a remote that can be removed from the set or a preset station selector, I haven't had chance to do more than take photos. I will investigate further. |