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Old 6th Apr 2017, 12:07 pm   #1
sobell1980
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Default MURPHY A272C Restoration.

Morning all.
Finally managed to get the next project on the work bench off the to do pile. This beautiful Murphy A272C in completely unmolested original condition. I collected it from Kenilworth last year from a house clearance. It even still has the hand written tag on it of the radios details. It also comes with original owners manual. I removed the back to find it draped with cobwebs and untouched.

This will really be the first project wireless wise this year after a long repair on a friends Rega planar 3 record player which swallowed all my spare time. Previously to that was the lengthy project of the HMV 653 which some of you may remember which was completed in November last year. So here it is. I've been looking forwards to this repair for some time now. I love the look of these old Murphys.
Made out my shopping list of caps as this thing is filled with Hunts caps.
Any comments or thoughts appreciated as ever.
Dave.
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Old 6th Apr 2017, 12:16 pm   #2
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Default Re: MURPHY A272C Restoration.

More pictures.
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Old 6th Apr 2017, 12:19 pm   #3
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Default Re: MURPHY A272C Restoration.

I assume regardless of the value all the Hunts caps shold be replaced . Even if they do work, they will not give much more service once back in use.
Dave.
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Old 6th Apr 2017, 1:18 pm   #4
MALC SCOTT
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Default Re: MURPHY A272C Restoration.

I have the same model radio playing now. I restored it many years ago and it still sounds great. I replaced all of the Hunts caps and quite a lot of perished rubber covered wire. FM was not so good, even with a brand new old stock ECC85. Fitting an ECC88 solved this problem. Good luck with the restoration, Malc.
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Old 6th Apr 2017, 1:24 pm   #5
sobell1980
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Default Re: MURPHY A272C Restoration.

Cheers, Malc.
Believe it or not the wife has agreed to have it in our bedroom that is currently being decorated. This is so we can listen to sounds of the 60s. Now it's on at 6am I can't listen to it in bed blasting out from my radiogram in the lounge. So this will be ideal. Can't believe the good lady suggested it !
Dave.
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Old 6th Apr 2017, 1:31 pm   #6
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Default Re: MURPHY A272C Restoration.

Hi Dave, my set is also in the bedroom. Her indoors hated it at first, but after 15 years or so she quite likes it, Malc.
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Old 6th Apr 2017, 1:33 pm   #7
sobell1980
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Default Re: MURPHY A272C Restoration.

Is yours the console version like mine?
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Old 6th Apr 2017, 2:02 pm   #8
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Default Re: MURPHY A272C Restoration.

Yes.
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Old 6th Apr 2017, 6:25 pm   #9
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Default Re: MURPHY A272C Restoration.

Plenty of the dreaded Hunts caps been changed today.
I thought I was going to be lucky and find the majority on that tag strip. They are tucked away in all sorts of confined spaces. Nice to have a proper project back on the bench.
Dave.
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Old 6th Apr 2017, 10:58 pm   #10
Leon Crampin
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Default Re: MURPHY A272C Restoration.

Consider modifying (slightly) the AF feedback network as detailed in my thread in "Success Stories". You can try it out on the A272C without removing the chassis.

These sets work well and seem to hold their alignment unless got at. Using an EZ40 rectifier gives more HT than the UU9, to the benefit of audio output. Watch the internal 'speaker switch - it's useless and best shorted out.

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Old 7th Apr 2017, 7:51 am   #11
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Default Re: MURPHY A272C Restoration.

Leon's thread here: https://www.vintage-radio.net/forum/...d.php?t=133550
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Old 7th Apr 2017, 8:48 am   #12
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Default Re: MURPHY A272C Restoration.

Thanks Nick. Will have a read of that.
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Old 7th Apr 2017, 9:02 am   #13
Edward Huggins
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Default Re: MURPHY A272C Restoration.

That under-chassis looks much tidier now. I would also check out the 10" speaker for any possible cone damage and that it still has a good compliance.
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Old 8th Apr 2017, 7:06 pm   #14
robin coleman
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Default Re: MURPHY A272C Restoration.

A lovely set, on my wish list. I have a 262 table model which looks similar.
Regards
Robin
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Old 10th Apr 2017, 9:59 am   #15
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Default Re: MURPHY A272C Restoration.

I hope you have more luck than me, I changed all the hunts caps, very time consuming but alas mine still doesn't work very well. I will revisit it as some stage when I've had a reasonable rest from it.
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Old 11th Apr 2017, 4:38 pm   #16
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Default Re: MURPHY A272C Restoration.

These are great performing sets once restored. Restored mine about 5 years ago and it's still going strong. Worth while changing all the hunts and waxies.

Peter
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Old 14th Apr 2017, 9:13 pm   #17
sobell1980
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Default Re: MURPHY A272C Restoration.

Yes Peter. I fully intend to change all those dreaded caps.
Just a couple left to do now. Had an hour on the set this afternoon. A few more waxies and hunts electrolytics changed. I'm really looking forwards to hearing this set working. I will get a nice braided mains lead ordered next week. I'm only changing the Hunts caps and leaving the very low value type caps in place and see how we go. I recapped an entire HMV 653 last year. It did lead to some major fault finding with a newly fitted cap had failed. A real headache. So at the moment just changing the obvious suspects.
Regards.
Dave.
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Old 15th Apr 2017, 7:08 am   #18
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Default Re: MURPHY A272C Restoration.

Changing the caps yesterday I noticed that C51, a 5uF electrolytic is fitted as such it is reverse polarity. Can antone help explain this to me please? Something to do with diode sections of v4 a and b on the diagram using trader sheet 1413 . Many thanks.
Dave.
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Old 15th Apr 2017, 8:51 am   #19
julie_m
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Default Re: MURPHY A272C Restoration.

The FM discriminator capacitor, in sets using an EABC80 or UABC80, is wired with its positive terminal to chassis. This is not an error. It's a consequence of the shared cathode.
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Old 15th Apr 2017, 8:53 am   #20
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Default Re: MURPHY A272C Restoration.

Quote:
Originally Posted by sobell1980 View Post
Changing the caps yesterday I noticed that C51, a 5uF electrolytic is fitted as such it is reverse polarity. Can antone help explain this to me please? Something to do with diode sections of v4 a and b on the diagram using trader sheet 1413 . Many thanks.
Dave.
It's not connected as reverse polarity, it's connected the correct way with +ve connected to chassis (as is the cathode of V4b) and -ve connected to the -ve output of V4a (it's anode)

EDIT: Post crossed.

Lawrence.
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