Murphy A98

[Beardyman]

Having never restored a Murphy I procured this one from a well known auction site which, coincidentally, was owned by Cobaltblue from this forum & also a new moderator (congratulations by the way!). He was also very kind to deliver it to me. After a bit of a scrub up the case was looking very good, only a few scratches here & there, concurrent with its age. A little bit of TLC & much time spent dusting the chassis revealed it was in pretty good shape too. The speaker had suffered from the effects of damp, the voice coil former was rubbing against the pole piece & this being an energised type speaker there wasn't a lot of options. After reading a few posts covering the same type of fault I decided to have a go at getting the corrosion out which, after perhaps 2-3 hours with various pieces of plastic, I was successful. Most of the rubber covered wire was crumbling, a few resistors were still in tolerance & all the electrolytic waxies were either in the process of failing or failed. The smoothing capacitor had a distinct bulge in the lid & suspicious looking white deposit around the seal. As this is quite a large part I had a go a re-stuffing it, again following advice from this forum. A quick look & you'd never know it wasn't original, very pleased. Surprisingly the scale bulbs were all good! All the valves had continuity on their filaments, but I was later to find out that one of them was a dud. I have found that often it isn't so much the electronics side of things that causes issues but more the aesthetic side. Needless to say the cloth covering the speaker board was tattered as is so often the case. Unfortunately a fair few of our local charity shops have closed for good, they were a good source of material off cuts etc. Anyway, all valves out, all the static resistance checks done it was powered up on the variac first. All good, voltages around where they should have been. I left it powered up on the bench for a while just to make sure the transformer was ok. After 30 minutes it was stone cold, breath a sigh of relief! Next all valves in & switch on. All valves glowing nicely, not thing from the speaker, silence. Quick whizz round with the meter showed the TH41 had no cathode volts, not a thing, both anodes were at full HT volts (265V) so no current being passed. Several checks of the circuit showed it should be working, the conclusion was a dud TH41. A request put on here swiftly had a response from Cathoderay57 who had a spare, many thanks! Fitting the new TH41 had the set booming, all wavebands working & sounding good. Attention was the turned to the volume knob which was a little slack on the shaft. Whether this was through wear or just time is hard to say. Where I work we use brass inserts made by a company called Tappex. After drilling the knob out to accept the insert you simply screw it in, drill the insert to fit the shaft, cross drill the insert & tap it to accept a grubscrew & its good as new. I've thoroughly enjoyed getting this set running again, it never fails to amaze me that it really takes so little to get them performing again, considering it was made in 1945 ti has survived well.

That 'speaker cloth gives the radio a fresh look, it also matches the push buttons. Colour coordinated as they say.

[HamishBoxer]

You picked a nice model there to restore and it looks superb.

[Cobaltblue]

That's a very nice job you have done there.

I am very happy that it lives again rather than spend another few decades in my Rountuit pile

I think that cloth is a great match.

Cheers

Mike T

[MurphyNut]

Really nice job, I recently restored a A90, basically the same set in a wooden case, I must admit I prefer your set in the Bakelite case.
They're really good radios and I often listen to mine.

[Beardyman]

Many thanks one & all, much appreciated.
The cloth is, in fact, blank tapestry/needlepoint canvas. My better half suggested it (it's one of her hobbies) as I was scratching around for ideas. Apparently it comes in a variety of colours too & is relatively cheap when compared to speaker cloth in general. It is rather stiff to work with though & once creased it will stay that way until ironed. All I need to do now is find a way to re-instate the rather shallow embossed legends on the dials etc.

[Beardyman]

Why do my success stories usually have an addendum or two?
The Murphy had a bit of a turn last weekend, it was working absolutely fine then the sound deteriorated to the point where it was basically distortion. I connected an external speaker & all was well, sounded good. The internal speaker had pretty much destroyed itself, cone detached from the frame all the way round, voice coil scraping (again, distorted by damp etc.) & several tears in the remaining cone material. The cone & voice coil had, at some point, been exposed to moisture & suffered the consequences. Using it finished it off! I took it apart to find the pole piece was covered from top to bottom in rust & a white deposit. I looked around for possible sources that may be able to repair it but to no avail. The few I contacted ran a mile as soon as I mentioned it was an energised type speaker, mutterings of "Don't have the test gear for them!" etc. I took the executive decision to fit a permanent magnet speaker whilst retaining the choke & relevant metalwork from the old speaker. Let's see what else goes wrong this weekend shall we?