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Sets, Parts and Service Information Wanted (private buyers only, no swaps) If you need help obtaining components, sets or equipment, post a message here. Private buyers only - no traders. No swaps.

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Old 12th Oct 2019, 8:01 pm   #1
Winsoxuk
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Default Ferguson 3V48 Tracking control Potentiometer

I wonder if you guys could help me. Im just resurrecting a Ferguson 3v48 and the tracking control potentiometer has failed it's a strange potentiometer as it has two parts inside. 1 potentiometer removes the whole manual tracking circuit by the look of its when it's set on the centre notch and the other one is just a basic potentiometer.

does anybody know where I can get one from it's very specific for this machine by the look of it.

Any help would be much appreciated

I don't have a circuit for this machine so any help would be appreciated the funny thing is it works ok without the potentiometer in it due to the preset tracking.
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Old 14th Oct 2019, 11:46 am   #2
ben
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Default Re: Ferguson 3V48 Tracking control Potentiometer

In my experience, these pots hardly ever (if ever) fail, unlike say the Revox presets which fall to bits.
Are you sure it cannot be resurrected by careful cleaning, regapping etc?
Bear in mind the symptoms you may see on screen may have another electronic or mechanial cause.
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Old 14th Oct 2019, 5:26 pm   #3
Winsoxuk
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Default Re: Ferguson 3V48 Tracking control Potentiometer

Unfortunately within the 1 assembly there are two wipers or brushes that push against potentiometers tracks. These are held in by three little blobs of melted plastic which prevent them from falling over when there is pressure placed on them these plastic spots have broken off I don't know how it happened I think it must be fatigue.

if the tracking is left in the centre these pots don't come into play as the sawtooth isn't biased against 0 or 5 volts that's what seems to happen when I have a put an oscilloscope on it you can see the DC level shift up and down when pressure is applied to the correct parts so the tracking does actually work it's definitely the tracking control that's at fault. I'll try and find a way of uploading a picture of it.
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Old 14th Oct 2019, 10:48 pm   #4
Goldieoldie
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Default Re: Ferguson 3V48 Tracking control Potentiometer

Hi
I have successfully repaired these type of pots ( Sony use this arrangement )
If you scrape with a sharp scarpel the plastic and metal wiper then clean with IPA
A tiny amount of jb weld underneath the metal where the plastic rivets were and then on top where the rivets came through
Leave for 24 hours to harden
Cheers
Pete
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Old 15th Oct 2019, 6:09 am   #5
Winsoxuk
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Default Re: Ferguson 3V48 Tracking control Potentiometer

What a great idea. I tried super glue but just fractures under the pressure. I'll give it a go and get back to you !

Cheers !
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Old 21st Oct 2019, 8:26 pm   #6
Winsoxuk
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Default Re: Ferguson 3V48 Tracking control Potentiometer

Well bad news...looks like the pots have been damaged with the wipers loose in there a sad day...I'm going to see if u can make something to fit it. Anyone have a manual or circuit for this section ? Thanks in advance
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Old 24th Oct 2019, 7:37 pm   #7
Winsoxuk
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Default Re: Ferguson 3V48 Tracking control Potentiometer

I've had to settle with setting tracking with alignment tape for the time being..good news is all my other VCRs are working again
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