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

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Old 6th Dec 2017, 8:43 pm   #1
kirstyd
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Default Fidelity HF?

Hi all
this machine has developed a fault. It will play well for about five minutes and then the sound distorts. Switching off and on cures the fault for a few minutes and then it happens again. When i got this machine it was a complete wreck but it did have a working amplifier so apart from replacing the cut off flex i have done nothing to the amp. Tested the cartridge in another machine and its fine. Any ideas guys? Not sure what model it is because the label was missing along with some of the Rexine. In one of the photos i am pointing at a capacitor that's looking a little rough.
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Old 6th Dec 2017, 8:49 pm   #2
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Default Re: Fidelity HF?

Smoothing capacitor on the way out? Did you hear any 'ripple' as part of the distortion? Not suggesting you switch it on again if that is the problem.
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Old 6th Dec 2017, 8:58 pm   #3
kirstyd
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Default Re: Fidelity HF?

No .the sound just starts to degrade about half way through the record 2 or 3 minutes
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Old 6th Dec 2017, 8:59 pm   #4
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Default Re: Fidelity HF?

Spray some freezer spray on that chip when it does it
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Old 6th Dec 2017, 9:42 pm   #5
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Default Re: Fidelity HF?

Resistors used in these amps were also not of the best quality and end caps could have bad connections.

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Old 6th Dec 2017, 9:59 pm   #6
kirstyd
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Default Re: Fidelity HF?

Well it seems like it was the smoothing cap after all .I replaced it [temporarily] with another and its been happily playing 45s for the last half hour .however this is the first time i have seen a capacitor rated this way [25 volts /1mO ] as apposed to MFDS .Can you explain please
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Old 6th Dec 2017, 10:48 pm   #7
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Default Re: Fidelity HF?

I think it's just that the unit (in this case millifarads) is used in place of the decimal point, as is often done with resistance values, so that the rating of the component can be expressed in only three characters.

So 1m0 is 1.0 mF, or 1000 uF. 4700 uF, or 4.7 mF would be 4m7, etc.
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Old 6th Dec 2017, 10:55 pm   #8
kirstyd
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Default Re: Fidelity HF?

Thanks Tom. The one I put in is 1500 mfds. Will it be OK or shall I change it?
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Old 6th Dec 2017, 11:38 pm   #9
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Default Re: Fidelity HF?

It'll be fine. The original 1000uF will simply have been the smallest value (cheapest part) that the designer could get away with.
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Old 7th Dec 2017, 12:49 am   #10
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Default Re: Fidelity HF?

Good news! Possibly just in time! You have done a lovely job of restoration - it looks very good.
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Old 7th Dec 2017, 11:58 am   #11
Edward Huggins
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Default Re: Fidelity HF?

Fidelity HF?? - I'm 99% sure this is a Fidelity HF45. The single chip amplifier version came in about 1967-68.
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Old 7th Dec 2017, 10:58 pm   #12
kirstyd
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Thanks Edward. I was thinking early 70's the deck being only a three speed. It was a total wreck when I got it. Part of the rexine was torn off. The knobs were missing along with its flex and the arm had been snapped off. It was originally a grey colour. I have to say it sounds rather good especially for a Fidelity. My grandson wanted one of those Crosley crapophones for Xmas. Well let me tell you he isn't getting one he is getting this instead.
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Old 7th Dec 2017, 10:59 pm   #13
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Default Re: Fidelity HF?

It does look good, like new.
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