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HMV 570A Radiogram

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freya
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Sitting down watching television yesterday when Christine chirps up from her facebook browsing with, would you like this, showing me a picture of what looked like a radio gram. Not really I said and carried on watching tv, now my mind started to wander back so I enquired after the price, £20 she said.....NO NO... must not start collecting more things.
Few hours later I said to Christine, see if he can get it in his car and drop of, couldn't loose really, must have some useful bits if it was no good, no such luck he had a sports BMW.
Next day and we had arranged to pick it up in Mother in Laws car (I don't drive any more) Its very very heavy, came with a whole bag of new bits and pieces. Noticed a valve was loose in the bottom in a very disintegrated box.
On arriving home the back was removed valve was removed from the cabinet whilst still in the car, luck me X2 its a new slightly boxed PX4. :bba
That's where I am at the moment, its now sitting in the kitchen being admired, I know nothing about radiograms or where to start (mechanically) so would like to call on the experts in this field when ready to proceed more and some techinal information would be good to read up on too.

 
Posted : 16/07/2015 1:34 pm
malcscott
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Any pics ??

 
Posted : 16/07/2015 1:39 pm
freya
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Few pics, I was reducing the size and posted the topic without them.
There are a few areas of veneer that need attention, there is a section of rosewood ? cross banding that's missing.

 
Posted : 16/07/2015 2:16 pm
Cathovisor
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570A is about 1934/5, K3 autochanger and surprisingly compact. A very nice machine that gives a good account of itself.

I'm hoping 'marconiman' sees this thread as he knows an awful lot about K3 changers...

http://www.radiomuseum.org/r/marconi_570.html

 
Posted : 16/07/2015 2:33 pm
freya
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There appears to be a panel that is possibly removable on the left hand side end to expose the underside of the main chassis ?, it shows signs of being forced at the top edges, with small amounts of damage. Is this un-clipped in some way or removed once something else is exposed. There are the obvious screws around the radio and deck, sound like a newbie :aab

 
Posted : 16/07/2015 2:46 pm
Cathovisor
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There appears to be a panel that is possibly removable on the left hand side end to expose the underside of the main chassis ?, it shows signs of being forced at the top edges, with small amounts of damage. Is this un-clipped in some way or removed once something else is exposed. There are the obvious screws around the radio and deck, sound like a newbie :aab

You will find that the screws on the radio panel are surprisingly long on the side of the cabinet where that panel is. This is because they hold that panel in place. Same as many other models, e.g. 540/541/542.

Undo those screws and the panel will come away: it's retained by dowels at the bottom. At least EMI were sparing a thought for their engineers by then - on my 524 you have to remove the chassis as a whole and it weighs a ton.

 
Posted : 16/07/2015 2:49 pm
Cathovisor
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... and thanks to the generosity of many (or people seeking to clear their sheds) I have several spare K3s...!

 
Posted : 16/07/2015 4:30 pm
freya
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Well I have taken the top and side panel off, more from curiosity than for a purpose.
I had to laugh, when my daughter ran past coming in from school she said "Dad its got macaroni valves in " :aaj

At a guess the silver block is the motor capacitor, the platter is laying flat in the wood at present, does this indicate that it has dropped on the spindle ?

 
Posted : 16/07/2015 4:56 pm
Cathovisor
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Hi Stephen,

here's some pictures of the K3 I have spare that 'marconiman' suggested might be useful for you.

Here also is a contemporary advert.

 
Posted : 26/07/2015 9:50 am
freya
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Well that turntable looks much flatter than mine, its amazing how Mazak can distort quite so much almost making you believe the profile is correct and something else is wrong.
That scan is very interesting, could you email a copy please so I can zoom it more please.
Will send a PM to further discuss the K3

 
Posted : 26/07/2015 10:22 am
Cathovisor
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Heavens above - that has drooped, hasn't it?!

You have both mail and a PM.

 
Posted : 26/07/2015 10:51 am
freya
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I suppose if could always wait for 80 years with it upside down in the hope gravity does it bit and straightens it :bba

 
Posted : 26/07/2015 11:13 am
Anonymous
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Is the motor an induction disc like the old electric meters? Or am I looking at something else.

Mike

 
Posted : 26/07/2015 12:17 pm
freya
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Its a hysteresis type motor i think.

 
Posted : 26/07/2015 12:26 pm
Cathovisor
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Is the motor an induction disc like the old electric meters? Or am I looking at something else.

Mike

Yep - standard EMI electric meter. :bba

 
Posted : 26/07/2015 5:58 pm
freya
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Although the post has been quiet of late, I have been busy. Thanks to Mike (Cathovisor) it looks like a decent turntable has been sorted.
My attention has turned to the main chassis, even getting it out is tricky due mainly to the weight. I must admit it sat on the bench with me just gazing at the various parts of aged crusty wiring.
A new day brought some determination to start on the capacitor block, at this point the genuine Marconi/HMV manual was not in my hands (it has hand drawings of the wiring) so plentiful photos and drawings were made, followed with very careful de-soldering of the crusty wires.
The process of extracting the old capacitors I decided on was to just press a flat blade screwdriver on the tar, it broke into small chunks very easily leaving the 12 radial capacitors exposed, two of which had a crude screen separating them from the others.
Rebuilding with modern equivalents was very easy using a common negative bar for most of the capacitors, the capacitor lead outs to the tag numbers was modified and instead of having individual wires taken up to the tags, a 1mm hole for each capacitor leadout was drilled beside the tag.
With the block now riveted back together and in situ again the soldering of those wires was straightforward because of the photos and drawings, right !!!, no way.
There was a couple of wires that needed to be verified and Mike came to the rescue with some extracts from the 296 manual.

So connecting up everything went well, the radio does pull in a couple of channels on a short piece of wire. My feeling is that there has been some tampering of the trimmers so an alignment may be necessary.
Using Gramophone input with a CD player provides a wonderful sound.

 
Posted : 06/08/2015 10:32 pm
freya
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Whilst waiting to start on the radio alignment procedure I decided to have a look at the crumbling screened link cable that connects the turntable pickup to the amplifier chassis, it comprises of a two core screened cable that's braided externally.
Given the diameter ((6mm) of the old crumbling crusty one I doubt the old conductors can be pulled out to be able to re use the braided outer sleeve, so any ideas please ?
The cable itself is proving a challenge also, it would seem that the modern cable types are much lighter duty inner cores which would make it look wrong with the plugs hanging off them, again are there any recommendations please.

Thanks as always

 
Posted : 12/08/2015 5:30 pm
EDDINNING
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Hi, I may have some braid about 10mm wide that can be "opened up" with a knitting needle and cable passed down the inside.
I've done this with more than 1 core and it looks authentic.

Ed

 
Posted : 12/08/2015 10:23 pm
freya
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That sounds very interesting Ed, please let me know if you do find some.
Thanks

 
Posted : 12/08/2015 11:25 pm
Brian Cuff
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Stephen, I have some copper braid sleeving of various diameters. It comes with a plastic tube in it to hold its shape until used. How long is the piece you require and is 6mm the final diameter? I can post some to you.
Cheers
Brian

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Posted : 13/08/2015 12:12 am
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