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

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Old 9th May 2021, 11:21 pm   #1
RojDW48
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Default ITT/KB record player - separate issue

When I first turned this on it was quite 'microphonic' - just a tap on the cab would result in a loud splat. I have poked around and cleaned extensively (a couple of trim pots seemed likely suspects) and it seems to have worked. However there remains an occasional volume drop - restorable by waggling the bass control or thumping the cab! Interestingly the satellite speaker/amp has exactly the same 'microphonic' fault. Any pointers? Is this a common fault with these? It doesn't sound at all bad when it's behaving itself.
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Old 10th May 2021, 7:49 am   #2
Edward Huggins
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Default Re: ITT/KB record player - separate issue

The "restorable" volume drop may well be just down to dirty potentiometer tracks on the 3 controls. Spray clean (Servisol 10) and let us know how you get on.
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Old 10th May 2021, 1:55 pm   #3
crackle
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Default Re: ITT/KB record player - separate issue

The circuit would suggest if the same fault is happening on the extension amplifier which is independently powered with independent controls, the fault must be somewhere in the pickup circuit.
Mike
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Old 10th May 2021, 5:12 pm   #4
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Default Re: ITT/KB record player - separate issue

Thanks Mike - the splatting in the satellite unit happens without connection to the mother player - nevertheless I think you are right, there is a problem with the input

Incidentally - I had a look at you nice museum. I couldn't see a pic of the 1933 model I sold unrestored quite a few years ago. Designed for KB by Betty Joel - the buyer was her nephew (or similarly related)! Beautifully put together it was.
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Old 10th May 2021, 8:07 pm   #5
crackle
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Default Re: ITT/KB record player - separate issue

If the "splatting" happens with the separate amp disconnected from the record player then it is unlikely to be the input as I first suggested.
I wonder if it could be a bias problem.
This player is an ITT-KB KP038, I have never owned one of these players but I have found in similar ITT-KB players of this age bias adjusting trimmers that are very unreliable and I have found they can wonder of value by a factor of maybe 5 times.
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Old 10th May 2021, 11:23 pm   #6
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Default Re: ITT/KB record player - separate issue

Hello again Mike - those are the very trimmers I suspected and thorough cleaning of the ones in the main player has probably cured the problem there - at least in the short term. I shall have another go at the ones in the satellite. Would it be worth replacing with fixed value components - if so, do you know offhand what would suffice?

KP 038 is right - don't advertise it, do they? Sticky label inside the amp !!

Cheers - Roger
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Old 11th May 2021, 3:42 pm   #7
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Default Re: ITT/KB record player - separate issue

There is a procedure described in the KB service manual for setting these trimmers correctly. https://www.service-data.com/product...6/13099/m19356
Yes I remember that 666 deluxe selling, I never had one in my collection hence why it is not on my website. But I believe you send me some photos for the Radio Museum.
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Old 12th May 2021, 11:40 am   #8
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Default Re: ITT/KB record player - separate issue

Yes I remember that 666 deluxe selling, I never had one in my collection hence why it is not on my website. But I believe you send me some photos for the Radio Museum.
Mike

So I did !! Memory not what it was
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