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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 17th May 2022, 2:40 pm   #1
YallaRiso
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Default Ferguson Record Player 3047B Audio Fault

Hello,

I was looking to see if I might be able to get a bit of help with an issue that's cropped up on my record player.

I recently acquired a Ferguson 3047B Record Player which within roughly 3 minutes of use ceased to play any audio out of the left speaker output.

For some additional context; when I initially started it up after roughly 3 minutes of play it emitted some smoke and made a dull buzzing noise through the left speaker. I immediately turned it off and proceeded to gently blow out the almost 60 years of dust that was inside – this stopped the smoke however this was when the issue occurred with the lack of audio output. However by plugging in and out the speaker a pop can be heard suggesting power is flowing through to the speaker.

My guess is that the fault lies in the stereo amplifier component and most likely with the left hand slider on the volume/balance mixer but this is a bit beyond my field of expertise so I'm mostly just using some guesswork and intuition.

If anyone would be kind enough to suggest anything I can do to fix this it would be massively appreciated – thanks in advance!
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Old 17th May 2022, 5:54 pm   #2
Edward Huggins
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Default Re: Ferguson Record Player 3047B Audio Fault

This does not sound good. Looking at a photo of this unit, I cannot readily see a headphone socket for you to test as an alternative output option to the speakers. It maybe worth trying some Contact Cleaner on the sliders, especially the Balance slider. How good are you with trouble shooting on old transistor players like this? There's a Service Sheet for this on the Link above - top RHS.
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Old 17th May 2022, 6:02 pm   #3
paulsherwin
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Default Re: Ferguson Record Player 3047B Audio Fault

Smoke is generally very bad news indeed. Try to identify what has burnt up.
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Old 17th May 2022, 6:20 pm   #4
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Default Re: Ferguson Record Player 3047B Audio Fault

Service sheet here: https://www.service-data.com/product...2/11103/m17972

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Old 18th May 2022, 7:14 am   #5
YallaRiso
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Default Re: Ferguson Record Player 3047B Audio Fault

Hi all, thanks for the advice on this one!

I've now purchased a copy of the service manual and had a wee check over the internals and given than a clean. The good news is that everything matches us with the circuitry looking relatively clean and no signs of burning... the bad news is that there's no obvious sign of what went wrong so I have little idea what the issue is.

I did also check the headphone output (located on the left hand side) and that is also only playing on the right hand headphone. Best guess is that something has burnt out in the amp circuitry but as the what I'm not sure. Is there anything I should be specifically looking out for?

Thanks again for all the help!
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Old 18th May 2022, 7:51 am   #6
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Default Re: Ferguson Record Player 3047B Audio Fault

It sounds daft, but use your nose to sniff around, as you'll often be able to locate the source of a burn-up like that.
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Old 18th May 2022, 7:51 am   #7
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Default Re: Ferguson Record Player 3047B Audio Fault

The fact that one channel still works suggests that the power supply section is OK, but the voltage could be being pulled down. I suggest checking whether you have 25V here (across C13) first. Reapplying power then using your eyes and nose may quicky reveal where the smoke came from.

If that's OK you're going to have to check voltages on the DC coupled output stage. Unfortunately a fault with one transistor here will take out the lot in that channel.
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Old 18th May 2022, 1:38 pm   #8
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Default Re: Ferguson Record Player 3047B Audio Fault

I don't know this particular model record player and haven't got a circuit diagram of it either. Having said that :-

I used to do repairs to record players, Music Centres, & Tape Recorders, at a "Thorn Electrical Industries" factory, back in the 1970's that made units under several different names including "Ferguson".

One of the most common components to 'burn-up' in transistor amplifiers at that time, were the resistors in the Emitters of the output Transistors, if a short occurred in one or both transistors, or a fault in the biasing or driver transistors, they would cook. (the output & Driver stages were nearly always D.C. coupled, so a fault in one stage can effect another). These Emitter resistors were normally '1' or '2.2' Ohms in value (depending on the output transistors used).

With the age of the unit. You now have to consider the Electrolytic capacitors (in particular), and I tend to change them 'on sight' even if they may still be OK at present. Fortunately, by the 1970's Paper Capacitors, had largely been superseded by more reliable 'Poly' types which rarely give any trouble.

As mentioned earlier, have a 'sniff' around for the burning smell, also check for burnt resistors or blown out electrolytic caps. Do replace the output coupling capacitors in BOTH channels (regardless of necessity), as a short in one or both, will destroy one or both of your loudspeakers.

I am, of course, assuming that the Amplifier follows the usual style of Amplifier design used in many "Thorn" built record players of the 1970's.
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Last edited by mister valve; 18th May 2022 at 1:46 pm.
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