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Old 8th Nov 2018, 8:51 pm   #1
Niall76
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Default Dynatron Record Player.

Hi all,

It's my first time posting here and just wanted a little advice. I just purchased a second hand Dynatron Cabinet with a Garrard turntable and a radio on the inside, exactly like the photo attached. The record player and radio seem to play fine however there is a problem with the sound.

Basically, every time you adjust the volume , or any of the audio settings, there is a loud hiss/crackle, very irritating! Any idea how I can fix this and if its fixable is it something I might be able to do myself? It's the first vintage player I've purchased.

Thanks again.
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Old 8th Nov 2018, 9:31 pm   #2
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Default Re: Dynatron Record Player.

You can probably make a worthwhile improvement and it doesn't take a lot of effort or skill.
Behind each of those controls is a thing called a "potentiometer" google some images and see what typical ones look like. They come in two sorts, rotary ones where as the name suggests you rotate a knob, and slide ones where the 'pot' is a long thin item with a slot in it through which protrudes a lug. A knob clips onto the lug, and you slide it to and fro.

Inside these things is a piece of insulation sheet (often a paper composite) with a thin deposit of carbon on it. This acts as a resistor, across which the circuitry makes a voltage, and a sliding contact scrapes along the carbon track to tap off a variable amount of the voltage.

With age and use these things go dry and the intermittent contact makes scratchy sounds if they are moved or disturbed.

Similarly switches in these things dry out and go scratchy.

A worthwhile improvement can be made by cleaning and re-lubricating them.

The usual way is to spray in a small shot of 'Electrolube' which is made for the job and hangs around to keep the pot/switch working well. DO NOT USE WD40. It doesn't work and it is immense trouble to get rid of the stuff and sort things out.

This usually works, but in severe cases the slider may have scratched all the carbon track off, and the pot will need to be replaced. Do-able, but first the right replacements have to be found and then some soldering is involved.. There are still people who do such repairs, or there is guidance on here for people venturing into DIY.

Oh, and welcome!

David
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Old 8th Nov 2018, 10:05 pm   #3
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Default Re: Dynatron Record Player.

Hopefully cleaning will work, well worth trying, easy to do and no dismantling.

Saying this item is vintage has just put 10 years on me, sold, installed and repaired them 40 odd years ago.
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Old 8th Nov 2018, 10:15 pm   #4
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Default Re: Dynatron Record Player.

I'll just add that the contact spray needs to be sprayed INTO the potentiometer so that it can reach the track and slider. There's generally a gap around the solder tags on the pot where you can insert the aerosol's extension nozzle.
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Old 8th Nov 2018, 10:42 pm   #5
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Default Re: Dynatron Record Player.

I think these are slider pots so can be accessed through the gap for the slider. Only problem I have had is the controls not sliding as freely after cleaning but were noise free.
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Old 9th Nov 2018, 12:07 am   #6
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Default Re: Dynatron Record Player.

Yes they are slider pots on this one. I repaired and refurbed the very same about a year ago. A quirky and attractive little design with its pull out speakers - good fun audio!
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Old 9th Nov 2018, 12:18 am   #7
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Default Re: Dynatron Record Player.

The only snag is with that style of cabinet, don't you need a powdered wig, knee breeches silk hose and a lunette glass to fully enter into the spirit?

Seriously, they're not a bad little unit. Middle of the road domestic electronics in a posh cabinet, that got left behind in the move to hifi.

David
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Old 9th Nov 2018, 4:16 pm   #8
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Default

Many thanks David I have googled a potentiometer so I've a better idea of what it might be, I figured it's got to be something to do with the switches. I shall order a spray of elctrolube so!!

Quote:
Originally Posted by Radio Wrangler View Post
You can probably make a worthwhile improvement and it doesn't take a lot of effort or skill.
Behind each of those controls is a thing called a "potentiometer" google some images and see what typical ones look like. They come in two sorts, rotary ones where as the name suggests you rotate a knob, and slide ones where the 'pot' is a long thin item with a slot in it through which protrudes a lug. A knob clips onto the lug, and you slide it to and fro.

Inside these things is a piece of insulation sheet (often a paper composite) with a thin deposit of carbon on it. This acts as a resistor, across which the circuitry makes a voltage, and a sliding contact scrapes along the carbon track to tap off a variable amount of the voltage.

With age and use these things go dry and the intermittent contact makes scratchy sounds if they are moved or disturbed.

Similarly switches in these things dry out and go scratchy.

A worthwhile improvement can be made by cleaning and re-lubricating them.

The usual way is to spray in a small shot of 'Electrolube' which is made for the job and hangs around to keep the pot/switch working well. DO NOT USE WD40. It doesn't work and it is immense trouble to get rid of the stuff and sort things out.

This usually works, but in severe cases the slider may have scratched all the carbon track off, and the pot will need to be replaced. Do-able, but first the right replacements have to be found and then some soldering is involved.. There are still people who do such repairs, or there is guidance on here for people venturing into DIY.

Oh, and welcome!

David
Quote:
Originally Posted by Nuvistor View Post
Hopefully cleaning will work, well worth trying, easy to do and no dismantling.

Saying this item is vintage has just put 10 years on me, sold, installed and repaired them 40 odd years ago.
Haha I think anything nowadays 20 years old is considered vintage! I feel the same when they describe the first playstations now as vintage. What do you think of them anyway? Have to admit it's an amazing design, never seen anything like them before which is why in had to purchase it

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Originally Posted by Station X View Post
I'll just add that the contact spray needs to be sprayed INTO the potentiometer so that it can reach the track and slider. There's generally a gap around the solder tags on the pot where you can insert the aerosol's extension nozzle.
Thanks Graham I will keep that in mind when I try it

Quote:
Originally Posted by RojDW48 View Post
Yes they are slider pots on this one. I repaired and refurbed the very same about a year ago. A quirky and attractive little design with its pull out speakers - good fun audio!
Yes indeed I think it's an amazing design for it's time! Never seen anything like it before! Any tips for attempting to get at the potentiometer to spray with electrolube?

Quote:
Originally Posted by Radio Wrangler View Post
The only snag is with that style of cabinet, don't you need a powdered wig, knee breeches silk hose and a lunette glass to fully enter into the spirit?

Seriously, they're not a bad little unit. Middle of the road domestic electronics in a posh cabinet, that got left behind in the move to hifi.

David
I'm guessing it might be awkward alright David I'll wait till I get some electrolube first before I look into it. Thanks yeah I've got to admit it's an amazing design for that era, and it's got to be reasonable enough with a Garrard turntable in it, what year do you think they came out in?
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Old 9th Nov 2018, 11:36 pm   #9
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Default Re: Dynatron Record Player.

I usually use 'Servisol Super 10' for cleaning pots., switches, etc. It comes in an aerosol can with a small tube for spraying into controls. Electrolube should be fine for this kind of job, too.
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Old 10th Nov 2018, 12:56 am   #10
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Default Re: Dynatron Record Player.

Thank you I just ordered some!
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Old 10th Nov 2018, 2:03 am   #11
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Default Re: Dynatron Record Player.

This is a photo of a slider pot, there are different designs but look similar. The slot in the pot is where the control knob slides along.
To clean you only need to spray a little of the Electrolube or whatever you get into that slot then work the control back and forwards. You can do this without dismantling from the top of the control panel. The spray should have a long spout to get into that slot.
Have the machine unplugged from the power and allow a little time for any of the solvents to evaporate before switching on.
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Old 10th Nov 2018, 9:20 am   #12
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Default Re: Dynatron Record Player.

Oh, and work the slider to and fro over its full movement a few times.

Work switches several times as well.

David
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Old 10th Nov 2018, 9:42 am   #13
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Default Re: Dynatron Record Player.

Noting the OP's question at the end of Post #8, I would date his (4 speaker) Dynatron unit as c.late 1969 to 1971.
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Old 10th Nov 2018, 12:01 pm   #14
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Default Re: Dynatron Record Player.

The radiogram in the photo looks to me like an HFC76 or one of its close relatives. Had one a few years ago and rather regret not hanging on to it. The HFC76 was also known as the Windsor and was introduced in about 1975. The OP mentions that his is fitted with a Garrard deck which would have been an SP25 Mk IV (not like the one in the photo) in the Windsor. There should be a label with a Dynatron model number on the back of the unit somewhere.

Alan

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Old 13th Nov 2018, 12:12 am   #15
Niall76
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Default Re: Dynatron Record Player.

Quote:
Originally Posted by Nuvistor View Post
This is a photo of a slider pot, there are different designs but look similar. The slot in the pot is where the control knob slides along.
To clean you only need to spray a little of the Electrolube or whatever you get into that slot then work the control back and forwards. You can do this without dismantling from the top of the control panel. The spray should have a long spout to get into that slot.
Have the machine unplugged from the power and allow a little time for any of the solvents to evaporate before switching on.
Thank you Frank, great information there but the only problem the control panel seems to cover the slots completely, I've attached a photo, not sure if the spray will get down through it

Quote:
Originally Posted by ajgriff View Post
The radiogram in the photo looks to me like an HFC76 or one of its close relatives. Had one a few years ago and rather regret not hanging on to it. The HFC76 was also known as the Windsor and was introduced in about 1975. The OP mentions that his is fitted with a Garrard deck which would have been an SP25 Mk IV (not like the one in the photo) in the Windsor. There should be a label with a Dynatron model number on the back of the unit somewhere.
Hi Alan I've had a look at the back and it is an. HFC77 so probably very similar to the model you mentioned.
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Old 13th Nov 2018, 11:06 am   #16
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Default Re: Dynatron Record Player.

The slot will probably have a split piece of material glued to the underside of the control panel to attempt to stop dust getting into the control.
If you use a torch and a soft piece of plastic to open up the cloth you will probably be able to see the control.
The spray should have a long spout to be able to reach the control.
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Old 13th Nov 2018, 1:43 pm   #17
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Default Re: Dynatron Record Player.

Hi Frank I've attached a couple of photos. You can take the slider knobs off but there seems to be very little space for a spray to go down into, seems completely covered.
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Old 13th Nov 2018, 11:44 pm   #18
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Default Re: Dynatron Record Player.

Will the nozzle of the spray fit in that slot?
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Old 14th Nov 2018, 12:14 am   #19
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Default Re: Dynatron Record Player.

Is it possible there are protective strips which move linearly with the knobs?
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Old 14th Nov 2018, 7:51 am   #20
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Default Re: Dynatron Record Player.

It is Graham but I seem remember they were strips of cloth with a slit in it. It is a while ago since the 1970’s so my memory could be wrong.
If it can’t be done through the control panel then there is a reasonable amount of dismantling to to do.
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