Pye MM

[AlanBeckett]

Joe,
A bit of both, combined with the season
Alan

[Yorkie]

The irony is Alan that when it's in place, it looks like a doddle of a job, when nothing could be further from the truth! I spent a most enjoyable morning with Joe today and saw the cabinet in all its splendour, patiently waiting to be reunited with its contents. I hadn't appreciate just how large that MMs are, and given the sorry state that it had been in Joe's done an excellent job in fettling it up, without making it look too 'newish'.

[AlanBeckett]

David,

Yes, it is surprising how big it is when you see it for the first time. It's a positive piece of furniture. Bear in mind it's supposed to be 'Transportable, hence the handles on the sides. I can't think that the lady of the house - these were a fearsome price - did much transporting. She probably summoned up the servants. The 'Internals' are equally imposing, and add to the weight. As it has a frame Aerial it's slightly surprising that it doesn't have a turntable.

The next job was to re-attach the Left side panel, which is just a job lot of screws, including a hidden one.

Finally, the disconnected wires on the RHS were re-attached. That had it's moments as they're not very accessible, and the 18SWG wire is about on the limit of my Weller. Anyway, it's done, or at least I thought so, until I discovered, on a final look round, that the wire connected to the bulb holder had a dry joint. The easy way to resolder this would be to (once again) remove the Control Panel - no way. After much long range poking with iron and solder I managed it, but it's a thing I wish I'd noticed earlier.

Next the Speaker assembly and the PSU.

Alan

       

[AlanBeckett]

When Joe disemboweled this he left the wiring intact. I disconnected the main chassis from the rest to work on it leaving the PSU connected to the speaker assembly. I can't remember whether Joe had already disconnected the Frame Aerial but it is now.

With the PSU and Speaker assembly on the bench two things were obvious. First that some of the interconnecting (rubber) wire hasn't survived the trip and second that a couple of my carefully attached labels had fallen off. That's no bid deal as I have the diagram and it's easy to trace where they belong. However it's interesting that they're both Red and yet one is a chassis wire. Perhaps Red denotes general HT and Return wiring.

So, there being little point in trying to preserve the decrepit wiring I chopped it in half so that I can work on the two parts in some comfort.

The mains connector, long gone, is a two flat blade afair. The two blades are different widths presumably to keep the mains supply the 'right way round'. That's slightly odd as the diagram shows a double pole switch and double wound mains transformer. No Earth is shown although there is a Note saying that the PSU Chassis is at Earth Potential. The Mains switch was, to put it kindly, sticky. However, a good dose of Plusgas and much wiggling loosened it up, and some Switch Cleaner and a tiny drop of oil looks to have sorted it. I've left it soaking for a bit.

Next the Speaker Assembly. This comprises the Speaker itself with its field coil and the Output Transformer. I've taken these into the house for further investigation. However, the Speaker looks to be in pretty good nick so I'm hopeful.

Alan


  PSUnSpeaker.JPG (Size: 3.51 MB / Downloads: 116)        

[Yorkie]

An obvious question I forgot to ask - does it work Alan, or is it too early to say until you've hooked it all up? Although it's a TRF, and in theory, less complex than a superhet, it does pose a few challenges, namely, the 'condenser' bank, the metal rectifier, and whether the field coil of the mains energised speaker is intact. All of these can be overcome, and given that the MM was introduced in 1932, the old boy may well be 80 next year, so some challenges are to be expected!

As to the price - £17 gns (£17.17s.0d) that equates to around £920 today, and whilst we may not think that's too outlandish for say a large screen colour TV - a 'must have' of the present day, back in the 1930s (the depression era), those people who did have work, had very little disposable income. As to carting it around the house from room to room in an era when even one radio was out of the reach of many people, let alone more than one radio, the maker's data sheet goes into detail about how to install an extension speaker, but of course that involved even more expense. Oh well, lugging it around the house was good exercise for those 'below stairs':D

The sheer size of the thing is a good indication that it wasn't amed at 2-up/2-down terrace houses!

Best of luck with the final phase Alan/Joe.

[Retired]

Hi,

You are making good progress now Alan and it's looking very promising. It's a good job Santa didn't try to deliver it to you; they are indeed a bulky set.

Being a TRF I bet it clears the wax out of your ears when you fire it up for the first time.

The pressure is on; are you going to complete it for Christmas?

I'm not surprised you are working on it "indoors", I've been working in the garage this afternoon and can confirm it's not only cold but feels cold as well.

Kind regards, Col.

[AlanBeckett]

Gentlemen,

We didn't try to fire it up due to the obvious problems. However, it's very solidly built and the one Col did worked without much electrical work, so I'm hopeful
I'm not sure about finishing it for Christmas but I do feel we may be on the last few laps now.
As far as the weather is concerned although it's been dry here today it's also seemed very bleak. My brief forays to the garage to get tools etc have been executed very smartly. My weather station currently shows 2 deg. C outside.

Alan

[AlanBeckett]

Last Post on this today I suspect.
I've measured the resistances of the various bits of the Speaker assembly and it all looks very promising. I can't measure the secondary side without disconnecting the speaker wires which I'm reluctant to do - they're tucked under the transformer. The primary side, while not exactly matching the diagram, are good enough for now. At least they're not O/C.
Next the PSU.

Alan

   

[Joe]

Satan's fart-stick's gonna get you!

- Joe

[Yorkie]

Last Post on this today I suspect.
I've measured the resistances of the various bits of the Speaker assembly and it all looks very promising. I can't measure the secondary side without disconnecting the speaker wires which I'm reluctant to do - they're tucked under the transformer. The primary side, while not exactly matching the diagram, are good enough for now. At least they're not O/C.
Next the PSU.

Alan

That's good news Alan - especially the field coil, L10 - thousands of turns of very fine wire - about 48SWG. No doubt you'll know that not only does it energise the speaker magnet, it also acts as a smoothing choke, so passes the full HT. In the event of excess HT current being drawn due to a fault condition, unfortunately, the field coil then acts as a fuse! The usual option adopted by less fastidious restorers is to simply replace the speaker with a modern PM one and an OPT, but on a set as old as this one, I think a re-wind would be called for.

Looking very promising!