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Old 22nd May 2024, 10:51 pm   #1
Paul_A_R
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Default Defiant A55 Dial Cord

I picked up a Defiant A55 which made plenty of noise when 9v was applied but the tuning dial moved a little right to left but not at all left to right.

The radio has been modified at some point to accept a PP9 , the earphone socket has been disconnected and the Plessey electrolytics replaced. The speaker negative has been connected through the C26 electrolytic presumably as part of the PP9 mod.

With the radio out of the case the dial cord could be freed and the radio tunes in to about as many medium wave stations as I can get here though with loud static. I will take the radio outside tomorrow to see if the interference reduces.

The cord remains on the drive drum when tuning left to right but comes off tuning right to left, eventually slipping behind the drum. It seems likely that the tuning dial will again get stuck eventually one the radio is back in its case.

Does anyone have any advice about resolving this issue?

Paul
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Old 23rd May 2024, 8:18 am   #2
Station X
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Default Re: Defiant A55 Dial Cord

Is the piece of metal at the top left of your second picture intended to stop the cord crossing over on the drum?
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Old 23rd May 2024, 2:28 pm   #3
Paul_A_R
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Default Re: Defiant A55 Dial Cord

The metal piece is part of the waveband changer. It does not seem to guide the cord. It occurred to me that as the set has been altered this part may not be fitted correctly and it should guide the cord.

I have a Magnox TR300 which I read on the forum uses the same Plessey chassis. I am not ready to start on this set but have dismantled it enough to take photographs of the cord assembly.

The Magnox has a vertical as opposed to a horizontal scale and the tension spring is in the drum rather than on the open cord behind the glass. Other than that it looks identical.

The cord can move from max to min in either direction without obstruction. The observed difference is that the cord does not cross over itself on the drum on the Magnox. On the Defiant the cord is crossed over and in one direction the cord underneath is pulled over the top of the cord on top and at this 'flip' point it skips out of the drum.

It looks like I will need to redo the cord though I will first try to get it to uncross it in situ.

Paul
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Old 23rd May 2024, 2:56 pm   #4
Paul_A_R
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Default Re: Defiant A55 Dial Cord

Oops.

Magnavox not Magnox.

Paul
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Old 23rd May 2024, 3:33 pm   #5
ronbryan
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Default Re: Defiant A55 Dial Cord

Here is a photo from the Contessa Mk3 manual, showing the dial stringing. This set was a kit made from surplus parts from the Defiant A55 when production ceased. I hope it is some help. Maybe the drum should be clamped closer to the chassis frame to reduce the angle made by the cord to the drum.


Ron
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Old 23rd May 2024, 4:48 pm   #6
Paul_A_R
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Default Re: Defiant A55 Dial Cord

Thanks. This is more detailed than the A55 trader sheet I am working from. I will have a look whether angles can be improved.

Paul
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Old 23rd May 2024, 6:09 pm   #7
Paul_A_R
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Default Re: Defiant A55 Dial Cord

Looking at the Contessa instructions the drum on my A55 was fitted upside down. I don't know whether that is important but it was a good excuse to take it off and start again with the cord. I noticed that the spring was longer than in the diagram. The drum also had more clearance from the chassis than seemed necessary giving more of an angle for the cord to negotiate.

I decided to leave the spring alone but replaced the drum as per the diagram but closer to the chassis and replaced the cord again using the diagram.

The cord can now move freely in either direction.

Thanks for the assistance.

Paul
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