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

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Old 14th Apr 2012, 7:35 pm   #1
Radio_Dave
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Default Pye Black Box

I've just got my first Black Box and I have a few questions.

Please look at the attached photo. Is there supposed to be two holes, drilled, in the back?

Should it have fittings for screw in "coffee table" legs on the bottom?

It's got a Monarch UA6 turntable and the mat is filthy. What is the best way of cleaning it, without causing damage?

Regards
David
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Old 14th Apr 2012, 7:53 pm   #2
Nickthedentist
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Default Re: Pye Black Box

Hi David,

There should indeed be two holes, though the lower one is usually the one through which the mains cable passes.

Here's a pic of one I restored a few years ago that I found on my PC. Obviously, the Nylon P-clip is non-original (though I think it looks nicer and works better than a knot), as is the gold coloured cable (mine had had its cable snipped off prior to sale).

I have seen the upper, recessed hole used to mount an external LS or tape out socket, but done by a dealer rather than at the factory.

No legs were ever fitted as far as I know. Certainly my four just have tiny rubber feet.

Look out for the OP tx being open-circuit on one half of the primary

Nick.
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Old 14th Apr 2012, 8:00 pm   #3
bobbyball
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Default Re: Pye Black Box

Hello, regarding the record deck, the mat will come off (either held on by "bumps" that press through holes in the turntable itself, or more likely just retained under the centre ring) and providing it hasn't gone hard or is cracked, then immersion in warm soapy water with gentle scrubbing will bring it up a treat!

Robert
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Old 14th Apr 2012, 8:40 pm   #4
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Default Re: Pye Black Box

A matching, similarly-contoured stand was available as an optional accessory, but I've only ever seen one. Presumably these were sold by Pye, but might possibly have been made by someone else.
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Old 14th Apr 2012, 9:04 pm   #5
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Default Re: Pye Black Box

Thanks for the replies
Quote:
Originally Posted by bobbyball View Post
immersion in warm soapy water with gentle scrubbing will bring it up a treat!
What type of soap? I once cleaned an old turntable mat with washing up liquid. It felt sticky, immediately, after and went totally rotten after six months.

Regards
David
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Old 14th Apr 2012, 11:47 pm   #6
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Default Re: Pye Black Box

I always dissolve a washing powder tablet in a pint of hot water and gently scrub with an old toothbrush, then rinse well and pat dry with paper kitchen roll. Never had one disintegrate yet.

Barry
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Old 15th Apr 2012, 7:51 am   #7
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Default Re: Pye Black Box

Mats of this age seem to be on the verge of deteriorating now anyway, so whatever you do, it still might go sticky at some point.

I used to remove the mat and place on some newspaper, spray liberally with Pledge, Mr Sheen or something similar, then scrub with an old rag.

Nick.
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Old 17th Apr 2012, 3:13 pm   #8
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Default Re: Pye Black Box

Quote:
Originally Posted by Nickthedentist View Post
Look out for the OP tx being open-circuit on one half of the primary
Just checked the output transformer and one half of the primary is open circuit.

I used the good half of the primary to calculate the turns ratio and arrived at, about, 110:1 (I think it should be 100:1). I've got an output transformer, from a Pye Fenman II, which has a turns ratio of 93:1. I imagine this would be close enough?

The Black Box had a primary resistance of 1700Ω but the Fenman II has only 660Ω. I don't understand the significance of this DC resistance, hopefully somebody will explain.

Regards
David
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Old 17th Apr 2012, 7:06 pm   #9
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Default Re: Pye Black Box

The resistance of the windings on a transformer is just that, resistance. It's not a particularly useful guide to number of turns, turns ratio or whatever since it depends on the gauge of the wire used as well as turns number and size of core etc etc.

The number of turns on an output transformer primary will depend on several factors, not the least of which is the compromise between cost and low frequency performance made by the designer. Needless to say, the better the performance required the (much) higher the cost.

As long as the turns ratio is somewhere near, and the primary dc current ratings are similar between the two transformers, the substitute will work OK. It may sound a bit different but in a mono unit that's probably not much of an issue as long as it sounds "OK".

You don't say which Black Box you have- the Fenman 2 amp is push pull but not ultralinear connection. If your BB is UL, you'll have to arrange screen feeds for the output pair and the sound quality may suffer a bit.
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Old 28th Apr 2012, 12:04 pm   #10
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Default Re: Pye Black Box

The service data suggests I should have a thrust washer between the turntable and ball race. Mine is missing, is it a just a flat washer or something more elaborate?

Please can somebody, also, tell me how many edges, of the lid, should have felt fitted

Regards
David
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Old 28th Apr 2012, 12:22 pm   #11
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Default Re: Pye Black Box

The thrust washer should be identical to that fitted beneath the ball race - a matching pair.

They often stick to the underside of the turntable, which is then put down on the bench. The washer is then dislodged, and gets lost!

It seems to be a plain washer but made of a bluish metal, rather thin, and presumably smoother and flatter than your average washer.

I suspect the same washer was used across the BSR range for decades, so your chances of finding a spare from someone here are high.

The lid should have left, right and curved front felted. Not the back where the hinge is.

Nick.

PS I have LOADS of pics of my UA6 stripped right down if you need any to look at. They're very modular and can be stripped completely without too much difficulty. Whether you need to is another matter though.
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Old 28th Apr 2012, 1:07 pm   #12
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Default Re: Pye Black Box

Thanks for the reply Nick.

I was going to use an ordinary washer but I now think I better try and find the proper part.

I'm hoping not to dismantle the turntable but if I do and I come unstuck, your photos could be very helpful.

Regards
David
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Old 28th Apr 2012, 1:15 pm   #13
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Default Re: Pye Black Box

Mine looked like it had been in a shed for 40 years so stripping down was the only way to go, but I wouldn't normally. Good learning experience though and not as daunting as it seems! I did have the luxury of a spare to look at when reassembling though.
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Old 28th Apr 2012, 1:17 pm   #14
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Default Re: Pye Black Box

Sorry to read that your OP tx is O/C on one side. All but one of the ones I've seen recently have been, even those stored in ideal conditions.

Ed Dinning did a great job of rewinding some of mine.

A small "universal" OP transformer from RS will get you some sound for very little outlay, but with nothing like the fidelity of the original.

Sorry, I'm not clever enough to tell you whether your Fenman tx, would be suitable.

Nick.
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Old 1st May 2012, 5:03 pm   #15
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Default Re: Pye Black Box

Hi Nick, I don't suppose one of your photos shows where this spring comes from

Regards
David
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Old 2nd May 2012, 10:15 pm   #16
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Default Re: Pye Black Box

Mmm, I know the feeling!

Might it be M139, Spring (Gate Actuating)? This is the shorter, uppermost compression spring on the dark red PU Spindle, M159.

Presume you've got all of the UA6 service sheet, including the exploded diagram with part numbers?

Sorry about the rubbishy pic and all the grime!

Nick.
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Old 2nd May 2012, 10:39 pm   #17
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Default Re: Pye Black Box

Excellent, thank you Nick. That's definitely where it goes.

I'm using the service data from Pauls CD, which doesn't have an exploded diagram. Is there a better version that I don't know about?

Regards
David
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Old 4th May 2012, 1:37 pm   #18
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Default Re: Pye Black Box

I've changed the six, Hunts, capacitors, reformed the reservoir/smoothing cap and fitted a Pye Fenman II output transformer.

I've just powered it up and the amplifier seems to work but there's an awful whistling noise which, quickly, becomes unbearable.

Any suggestion where I should start?

Thanks
David
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Old 4th May 2012, 1:42 pm   #19
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Default Re: Pye Black Box

ISTR these use negative feedback from the secondary of the OP transformer.

Maybe you've got yourself postive feedback? Try reversing the polarity of the connections to the secondary and see what happens.

Nick.
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Old 4th May 2012, 4:24 pm   #20
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Default Re: Pye Black Box

Thanks Nick, you were spot on.

The amplifier is, now, working well but I'm a bit concerned about the motor. How hot should they get? I've been playing records for, around, an hour and I can't keep my fingers on the motor.

Regards
David
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