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Old 21st Apr 2017, 11:44 am   #21
Edward Huggins
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Default Re: Info on Pye Black Box G63

A great unit. You will enjoy. The AT6 is ideal in this.
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Old 22nd Apr 2017, 5:52 am   #22
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Default Re: Info on Pye Black Box G63

Here's the G63 with the lids off. The turntable cut out is for a Garrard 210 by the looks of it, but the early AT6 has the same mounting hole spacing and drops in neatly. I'd guessed this would be the case, but I wasn't completely sure, and if it had been an RC120 cut out I would have had trouble using the AT6. As it is, the AT6 transit screws can't use the 210 transit holes, so I'll take them off the turntable for the time being.

The second picture is the amplifier compartment. There was a lot of extra wiring on this side, plus another big power transformer which I asked Hollie to remove. So I suspect that there are problems with the amplifier power supply. Other older wiring suggest that the gram was switchable between the internal record player and some external mono source, perhaps a radio. I may put this feature back once the amp's repaired.
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Old 22nd Apr 2017, 9:33 am   #23
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Default Re: Info on Pye Black Box G63

That chassis looks fairly normal to me with the original mains TX in situ. Don't know why there was another TX in there, unless it was used as a replacement for the original semi-shrouded one. As to external connecting circuitry, this may not be original? Do make sure the AT6 chassis is not fouling anywere around the motor board cut out.
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Old 23rd Jun 2017, 2:54 am   #24
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Default Re: Info on Pye Black Box G63

I've now pulled the chassis out to check it. The insulation resistance of the power transformer is 100 megohm at 600V. Is that in the acceptable range? I notice that the player doesn't have a mains earth, which might be OK for the amp because the knobs are plastic, but then there's the turntable which has exposed metal connected to the amp. I'll have to add proper earthing.
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Old 23rd Jun 2017, 1:23 pm   #25
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Default Re: Info on Pye Black Box G63

It sounds as if this has been modified somewhat. These were made with Red, Green and Black 3 core cable and the mains TX was a good quality fully isolated one.
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Old 23rd Jun 2017, 7:45 pm   #26
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Default Re: Info on Pye Black Box G63

HI Sue, 100Meg should be fine, but to be absolutely sure run the transformer on no load until it warms up and re-check the insulation resistance, no significant reduction and it is fine.

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Old 25th Jun 2017, 9:34 am   #27
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Default Re: Info on Pye Black Box G63

The power transformer has passed the test, but the right channel output transformer is burnt out on one side from a leaky coupling capacitor. (The culprit is a 0.05uF TCC Visconol-X Metalmite which is acting like a 5 meg resistor.) Because of the phase-splitting circuit it's also damaged the components around the triode section of the ECL82. I think I can get the transformer rewound, but before I do, does anyone have a spare?
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Old 26th Jun 2017, 9:41 pm   #28
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Default Re: Info on Pye Black Box G63

Hi Sue, OPT looks like those from other types of BB. not the strongest of components and I've rewound a few. They are quite simple to reverse engineer.
when you check the circuit see if there is a CR circuit across the transformer (anodes to HT). In the PCL83 mono version of this unit they were shown incorrectly on the circuit drawing.
It will also be worth check with a scope that there are no ultrasonic oscillations in the amp. the PCL83 version was prone to this and had no less than 3 feedback networks, including a piece of resistance wire for current feedback.

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Old 27th Jun 2017, 8:13 am   #29
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Default Re: Info on Pye Black Box G63

Here's one of the output transformers. It's just under three inches wide and two inches tall, and it has two 0.004uf capacitors wired across power connection and the anode connections. The negative feedback is simple, just 150 ohm in parallel with 0.01uF from the loudspeaker coil to the cathode of one of the triode sections. This triode then drives the other triode out of phase, which is the tricky bit for me to follow.

How do you get the layer of pitch or whatever it is off the transformer? Would a low oven do it?
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Old 27th Jun 2017, 12:38 pm   #30
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Default Re: Info on Pye Black Box G63

Not that cool but 200C should do it.


Not normally recommended as a way of ensuring domestic harmony, but if you are SWMBO feel free to go ahead
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Old 27th Jun 2017, 2:02 pm   #31
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Default Re: Info on Pye Black Box G63

Well, it's a bohemian household, so there's never been a problem drying paint in the oven or soldering on the dining table, which is melamine, fortunately!
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Old 27th Jun 2017, 5:57 pm   #32
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Just don't expect rhapsodies over pitch flavoured roasts!
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Old 27th Jun 2017, 9:30 pm   #33
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Default Re: Info on Pye Black Box G63

Hi Sue, wrap in poly bag and put in the freezer. The pitch will then chip off easily.
you may need to clean the lams before re-assembly in petrol/ paraffin to get them all back in the bobbin.

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Old 3rd Jul 2017, 2:26 pm   #34
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Default Re: Info on Pye Black Box G63

For reference, here is the unrestored chassis, build date circa June 1961, chassis number 138886.
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Old 21st Jul 2017, 10:24 am   #35
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Default Re: Info on Pye Black Box G63

I've restored the chassis, had the faulty output transformer rewound, and tested it out with spare speakers and a Philips personal CD player as programme source. Everything worked, except after an hour the filter capacitor can got hot, which explains why the previous owner was running it from an external power supply. So in went a similar sized Nippon Chemicon filter can, but because this was 20+ 20uf rather than 10 + 50uF, I added an Elna 32uF underneath. All the paper caps apart from the four Hunts 0.004uF bridging the output transformers needed replacing, along with a couple of other electrolytics, but the Suflex polystyrenes in the tone circuits were still good.
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Old 6th Sep 2017, 2:19 pm   #36
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Default Re: Info on Pye Black Box G63

It's all back together and working well now. I don't have operating instructions, but following the wiring it seems the two tone controls are passive treble and bass cut working in opposite directions. That is, for maximum treble, the Treble knob is turned fully anticlockwise, and for maximum bass, the Bass knob is turned fully clockwise. The amplifier's response should be close to flat with the controls in these extreme positions, but I find it best to leave the bass at maximum, and adjust the treble to suit the record I'm playing. I'm quite pleased with the overall sound of the Pye, and I've decided to put my other changers into storage. At the moment I'm trying a BSR TC8M in a spare headshell for playing 78s and mono LPs and 45s.
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Old 11th Sep 2017, 11:28 am   #37
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Default Re: Info on Pye Black Box G63

I've replaced the missing knob bright with a reasonable replica made by cutting the end off a 1970s spun aluminium clad plastic knob, and dishing the face by pressing a spoon on it. Of course there were scratches created in the process, but afterwards I stuck the bright on the end of a drill chuck with blue tack and spun it with steel wool. A thin coat of yellow lacquer, and it now looks something like brass. The replica is the knob on the lower left of the picture. I'm pleased that I don't have to spend big bucks on a red Hacker Herald just for a tiny bit of pressed metal!
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Old 11th Sep 2017, 11:56 am   #38
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Default Re: Info on Pye Black Box G63

Brilliant. In some cases I have been able to use the Gold/Silver foil (on say tea bags and coffee jar tops) neatly glued and smoothed out onto the knob's plastic surface where the original dome/chinese hat has gone missing.
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Old 12th Sep 2017, 5:47 am   #39
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Default Re: Info on Pye Black Box G63

Edward, there's self-adhesive stuff called Bare Metal Foil that modellers use to give a bright silver or gold finish to plastic parts. It has the advantage of being soft enough to follow complex shapes when it's rubbed down, although that also means it can scratch easily with rough handling. I couldn't use it for the G63 because the knobs have grooves in the plastic under the brights, I presume to take excess glue when the bright is pressed on.
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