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

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Old 7th Dec 2013, 5:36 pm   #41
Radio Wrangler
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Default Re: Pye Black Box

Where do the red and black wires from that plug go to?

David
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Old 7th Dec 2013, 5:50 pm   #42
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Default Re: Pye Black Box

They weren't attached to anything when I got it. There is scorch marks on the end of the wire too.
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Old 7th Dec 2013, 7:29 pm   #43
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Default Re: Pye Black Box



Disconnect that plug!

Perhaps for next check, you could link the centre and 240V sockets on the voltage selector with some soldered wire and repeat the mains off resistance checks suggested earlier.
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Old 7th Dec 2013, 8:00 pm   #44
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Default Re: Pye Black Box

I've just resoldered the joints on the on/off switch and the primary tag on the transformer and noticed that the joint on the transformer was loose! I then read Chris' post and as I was pulling out the plug the bulb lit up. On further investigation (wiggling) it became apparent that the fixings for the plug had expanded and was not making contact. A quick squeeze and now it appears I have power. I get readings of:-

114v on Primaries
24v on first Secondary
3v on second Secondary

Do these readings look about right?

Kevin
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Old 7th Dec 2013, 8:13 pm   #45
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Default Re: Pye Black Box

Not quite - they're all half of what you should be getting - but you're getting there!

You should get the mains voltage on the primary, which should be 240V or thereabouts.

Try measuring directly across the mains (e.g. where it goes into the on/off switch) and see what voltage you get.

N.
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Old 7th Dec 2013, 8:32 pm   #46
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Default Re: Pye Black Box

Would 114V be across each of 2 primaries (series wired for 240v) I can't see how else you would get 114V on the primary side. This would be correct but doesn't explain the low secondary voltages. Heavy overload perhaps? It is still fitted with old capacitors.

The two wires go to the deck motor, and are directly connected to the output side of the mains switch. There should be 240V on these wires with the mains switch in the on position. Make sure these are safely insulated or disconnected from the voltage select plug if they are not used.

Do you have the circuit diagram?

Last edited by matthewhouse; 7th Dec 2013 at 8:39 pm.
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Old 7th Dec 2013, 8:33 pm   #47
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Default Re: Pye Black Box

230v at switch. Checking the wires at the voltage selector the red wire from the primary goes to tag on 90v-120v part. Turned the plug round and got 235v at primary tags. Valves and bulb lit up like Blackpool illuminations . Not sure if that's a good thing!

Kevin
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Old 7th Dec 2013, 8:40 pm   #48
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Default Re: Pye Black Box

No, not a good thing! Suspect you had it on the 90-120V setting!

BTW has anyone got a circuit for this? Is it on Paul's discs, and if so, where?
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Old 7th Dec 2013, 8:49 pm   #49
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Default Re: Pye Black Box

Well, at least some power went through the transformer. Unless the winding from the 120 to 240v taps is open, then it might be something fixable. Hope you switched it off rather quickly.

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Old 7th Dec 2013, 8:53 pm   #50
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Default Re: Pye Black Box

Looking at that last picture is that Red/Yellow cap melted?
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Old 7th Dec 2013, 8:58 pm   #51
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Default Re: Pye Black Box

Cap has been changed for exactly that reason.
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Old 7th Dec 2013, 9:03 pm   #52
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I'm guessing you are measuring from 0V and the 110V tap of the primary. If you leave the unit powered in this condition, with 235V on the 110V tap expensive damage will result. Please check the voltage selector is set correctly before powering again. Double HT voltage can cause the HT capacitor can to explode, with the risk of serious injury. Please check you are measuring from the correct tags.

With the tap set correctly, carefully measure the AC voltage across the 2 centre tags (which have thin blue and black wires going to the mains transformer) on the rectifier at the bottom left of your photo.
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Old 7th Dec 2013, 9:21 pm   #53
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Default Re: Pye Black Box

Voltage selector is in the 225-250v position (pic1) I am measuring across the tags highlighted in pic2. I got 212v across the black and blues wires on the rectifier

Kevin
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Old 7th Dec 2013, 9:39 pm   #54
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Default Re: Pye Black Box

212V is much more like it! far better than the 24V you had before.

As the HT winding seems to work as does the primary, are the valves glowing a gentle orange now?
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Old 7th Dec 2013, 9:48 pm   #55
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Default Re: Pye Black Box

Can someone tell me which are the secondary tags, yellow or green. If it's the yellow tags then I was measuring at the wrong place! Valves are glowing a gentle orange yes.

Kevin
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Old 7th Dec 2013, 9:56 pm   #56
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Default Re: Pye Black Box

I have attached pic, there are 5 secondary tags 3 for LT 2 for HT, If the PLC83 have their heaters in series the voltage will be about 25V AC if they are parallel wired the voltage will be about 12.5V AC.

The 6.3V winding feeds the bulb and the ECC82 heater.

The HT winding feeds the input of the bridge rectifier which you measured at 212V

I can't work out the 4 primary wires from the photos but as long as they haven't been disconnected and fitted back wrong there is no need to measure here.
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Old 7th Dec 2013, 10:04 pm   #57
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Default Re: Pye Black Box

The 24v I measured before was across the tags you've marked as 25v. I get 4v where you've marked 6.3v. The 4 primary wires are white and red then blue and black.
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Old 7th Dec 2013, 10:22 pm   #58
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Default Re: Pye Black Box

As the valves and bulb are lit sensibly and you have ht into the rectifier, the transformer side is likely fine.

You should get sound out of it now when connected back up to the record deck. If it does work now, don't operate it for long without first replacing C6, C7, C9 and C10 all are 0.04uF. This part number is a suitable replacement.

The rectifier will probably need replacement too but get it sort of working before replacing too many parts as it's easy to introduce difficult to find faults if mass component changes are carried out without testing after each component is replaced.
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Old 7th Dec 2013, 10:31 pm   #59
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Default Re: Pye Black Box

I have changed those capacitors already. I will put it all back together tomorrow and see if there's sound. Thanks for everyone's help so far.

Kevin
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Old 7th Dec 2013, 10:32 pm   #60
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Default Re: Pye Black Box

Good stuff, you can't be far away from getting it working now!
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