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Old 1st Nov 2019, 4:09 pm   #41
Levente
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Default Re: Vintage Radio and Phonograph cutter schematic

that means wherever I go with this or plug that in I do need to check the wall socket which is the Live and Neutral? I did mark now the sides with a red tape on the step down converter and also on the plug itslef...

there is only a slight hum, will solder back the Y cap and see what happens...

Thanks Lawrence for your help!
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Old 1st Nov 2019, 4:46 pm   #42
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Default Re: Vintage Radio and Phonograph cutter schematic

All wall sockets should be wired the same unless someone has wired them incorrectly, in the UK looking at the wall socket the Live is on the right and the Neutral is on the left if they have been wired correctly.

With the electricity supply I have here the Neutral is connected to an Earth mat buried in the ground back at the pole that the electricity distributors supply transformer is mounted on and at various points between there and the house, before the distributors Neutral connects to the electricity meter at the house it's connected to the main Earthing conductor that's connected to the consumer unit and from there via the various Earthing conductors to all the mains outlets.

Lawrence.
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Old 1st Nov 2019, 4:59 pm   #43
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Default Re: Vintage Radio and Phonograph cutter schematic

Thanks... here the live is on the left side..i was not aware of that, just reading online articles...the question is which of the two prong should go to the left then... or just test it first..wonder if incorrectly plugged in which happened several times, did damage any other components connected to ground on the chassis...
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Old 1st Nov 2019, 5:52 pm   #44
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Default Re: Vintage Radio and Phonograph cutter schematic

Reversing the two prong mains plug shouldn't have caused any damage.

Lawrence.
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Old 1st Nov 2019, 5:55 pm   #45
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Default Re: Vintage Radio and Phonograph cutter schematic

Thanks Lawrence for this. Have a great evening.
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Old 3rd Nov 2019, 4:18 pm   #46
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Default Re: Vintage Radio and Phonograph cutter schematic

Hey Lawrence, hope you a great Sunday there... just a quick question if I may.

Is it possible to disconnect that speaker field? and using one filter cap of 30uF instead? Just a thought as I would like to hook this up with a better external speaker...

Would this work? Or that speaker field needs to be there for the correct operation.

Thank you.

Levente
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Old 3rd Nov 2019, 4:51 pm   #47
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Default Re: Vintage Radio and Phonograph cutter schematic

No, don't bypass the field coil of the internal loudspeaker, that winding is essential for the proper operation of the unit.

An external loudspeaker can be used plugged into the jack socket provided.

That will disconnect the internal loudspeakers voice coil, the external loudspeaker can be either of the permanent magnet type or the electrodynamic type, if an electrodynamic type is used it will have to have its own field coil supply.

Lawrence.
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Old 3rd Nov 2019, 4:52 pm   #48
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Default Re: Vintage Radio and Phonograph cutter schematic

Thank you so much ! Understood.

Levente
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Old 6th Nov 2019, 12:52 pm   #49
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Originally Posted by ms660 View Post
No, don't bypass the field coil of the internal loudspeaker, that winding is essential for the proper operation of the unit.

An external loudspeaker can be used plugged into the jack socket provided.

That will disconnect the internal loudspeakers voice coil, the external loudspeaker can be either of the permanent magnet type or the electrodynamic type, if an electrodynamic type is used it will have to have its own field coil supply.

Lawrence.

Hey Lawrence, another quick question and thank you for your advise in advance as always...

I thinking to change the value for the second filter capacitor. Would a 100uF ,275 WKG 350 Surge be an acceptable choice? I know the voltage calls for a 450V rated cap but there I will not get more than 250V and these can capacitors I have are really a god quality.

I kept the first filter connected to the 5Y3 the same 16uF/450V

Would this reduce the hum?

Many thanks!
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Old 6th Nov 2019, 1:46 pm   #50
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Hey Lawrence, another quick question and thank you for your advise in advance as always...

I thinking to change the value for the second filter capacitor. Would a 100uF ,275 WKG 350 Surge be an acceptable choice? I know the voltage calls for a 450V rated cap but there I will not get more than 250V and these can capacitors I have are really a god quality.

I kept the first filter connected to the 5Y3 the same 16uF/450V

Would this reduce the hum?

!
It should be rated the same as the reservoir capacitor which is 450 volts, here's why...

1) The rectifier is a directly heated rectifier, the rest of the valves aren't, that means that the voltage on the rectifiers cathode and the rest of the HT line can be much higher than it otherwise would be after the other valves have warmed up and drawing their full current.

2) A fault condition could exist such as the heater supply for all the valves other than the rectifier goes missing for whatever reason, ie: poor connection, open circuit heater winding on the transformer etc, if that were to happen the HT voltage would rise to the peak value of the AC voltage that's presented to the rectifiers anode(s) The manual gives a figure of 320 volts AC at the anode(s) that is the RMS value, however, as said, the reservoir capacitor would charge up to the peak voltage of the AC therefore putting the HT line at a DC voltage that's equal to the peak of the AC voltage, the peak value of a sinusoidal AC voltage is its RMS value multiplied by 1.414, ie: 320*1.414 which equals approx. 450 volts....

Would increasing that capacitors value reduce the hum to a noticeable extent....It depends where the hum is coming from, soon find out if a suitable one is fitted.

Lawrence.

Last edited by ms660; 6th Nov 2019 at 1:59 pm. Reason: clarity
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Old 6th Nov 2019, 3:16 pm   #51
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Default Re: Vintage Radio and Phonograph cutter schematic

Thanks a million for this explanation. I did not know these at all.
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Old 9th Nov 2019, 3:30 pm   #52
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Default Re: Vintage Radio and Phonograph cutter schematic

Hello again !

I did go through again all of the components, capacitors and again a full on voltage readings.

I also put one new old stock 6v6GT in.

Sadly there is still a massive mains hum in there and some blue light appears on the 6v6 tube. Attached some pictures of all the tubes in place.

...anything I tap on this player, the side the top, all the tubes if I tap them I can hear it in the speaker and in the headphone. Just like a massive microphonic effect.. If I switch on the motor, I can hear the motor noise also in the headphone and the speaker too.

What could be wrong here? this hum is really loud and disturbing.

and now as soon as I switch it on, a fast popping sound is heard in a fast repetitive pattern and slowing down ...on the top of that massive hum .... and now is squealing like crazy when I turn the volume up !
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Last edited by Levente; 9th Nov 2019 at 3:58 pm.
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Old 9th Nov 2019, 4:10 pm   #53
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Default Re: Vintage Radio and Phonograph cutter schematic

Is the loud hum there when the volume controls are turned to minimum ?

Lawrence.
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Old 9th Nov 2019, 4:20 pm   #54
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Is it the loud hum there when the volume controls are turned to minimum ?

Lawrence.
Both... popping sound and hum is there when the volume control is down, but when I start to turn up the hum gets even higher and louder and then a massive squealing starts...

I have several 6v6s and tried a few, all are having the same effect


I do not have another 6SC7 I am unsure on that

the 6SJ7s i have one extra so started swap them one by one, no change and I have none of the rest of the 6SA or 6SF tubes..

I was reading the robribinette site for trouble shooting but with these sounds, and those repeating popping (is that the osculation?) and squealing can be anything...

I am also really suspicious of the on/off switch pot.. the pot responds weirdly...

thinking of where should I start...

cleaning the tube sockets
check again the soldering? poking around with a chopstick?
ground connections... on the chassis counted 5 ground points in total
getting better filter caps?


Thanks Lawrence
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Old 9th Nov 2019, 4:25 pm   #55
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Default Re: Vintage Radio and Phonograph cutter schematic

For instability and hum I would check the HT filter capacitor (electrolytic)

If no joy then short the control grids of V5 to chassis, that's pin 3 and 4 of the 6SC7 to chassis and note any difference.

Lawrence.
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Old 9th Nov 2019, 4:38 pm   #56
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Default Re: Vintage Radio and Phonograph cutter schematic

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For instability and hum I would check the HT filter capacitor (electrolytic)

If no joy then short the control grids of V5 to chassis, that's pin 3 and 4 of the 6SC7 to chassis and note any difference.

Lawrence.

Flipped the chassis up and started to poke around. Before that checked in the dark, no spark I saw.

Then just as you said Lawrence, the second filter electrolytic cap which +ve has 3 leads connected to..now as soon as started to move thos leads or poked on that cap it is definitely something there.

For some reason now up side down it does not squealing. But the hum is there.

I only have a very small size new electrolytic cap.. would be that OK to try? It is not a massive can capacitor but rated 22uF 450V and designed for low profile PSUs (modern ones) ?

If this is OK will try this first then shorting the pins on the 6SC7 or shall i just do it anyway? Thanks a lot Lawrence.

Last edited by Levente; 9th Nov 2019 at 4:52 pm.
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Old 9th Nov 2019, 6:17 pm   #57
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Default Re: Vintage Radio and Phonograph cutter schematic

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For instability and hum I would check the HT filter capacitor (electrolytic)

If no joy then short the control grids of V5 to chassis, that's pin 3 and 4 of the 6SC7 to chassis and note any difference.

Lawrence.
I did tie the pin 3 and 4 together to chassis. Unfortunately no sound is coming through the speaker or no sound on the external speaker plug either.

Hum is reduced and no any other issues but the sound has gone...
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Old 9th Nov 2019, 6:48 pm   #58
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I did tie the pin 3 and 4 together to chassis. Unfortunately no sound is coming through the speaker or no sound on the external speaker plug either.

Hum is reduced and no any other issues but the sound has gone...
It will kill the sound, that's part of the test, if shorting those grids to chassis has got rid of the loud hum you had with the volume controls turned down then remove the short from one grid and see if the hum gets loud again (volume controls still turned down) if it doesn't then remove the short from the other grid, that should tell you which grid the loud hum is coming in on, let us know which grid it is, ie: pin 3 or pin 4.

Lawrence
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Old 9th Nov 2019, 7:33 pm   #59
Levente
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Quote:
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I did tie the pin 3 and 4 together to chassis. Unfortunately no sound is coming through the speaker or no sound on the external speaker plug either.

Hum is reduced and no any other issues but the sound has gone...
It will kill the sound, that's part of the test, if shorting those grids to chassis has got rid of the loud hum you had with the volume controls turned down then remove the short from one grid and see if the hum gets loud again (volume controls still turned down) if it doesn't then remove the short from the other grid, that should tell you which grid the loud hum is coming in on, let us know which grid it is, ie: pin 3 or pin 4.

Lawrence
Aaaa okay.

With the volume pot down, now there is not much hum like before (when the other capacitor was in place) I did change the 8B cap.

If I turn up slightly the volume, then I can hear the hum and with the volume control the hum increasing and decreasing.

If I ground pin 4 the hum has gone. If I remove the short hum comes back.

If I ground pin 3 does not seem to change anything at all. Same results grounded or not grounded.

Thanks for helping me on this.
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Old 9th Nov 2019, 8:09 pm   #60
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Default Re: Vintage Radio and Phonograph cutter schematic

Just looking back at Post#41, only slight hum was reported, I would check everything done since then and also determine whether the hum is 50Hz (mains, heaters etc) or 100Hz (HT ripple)

Lawrence.
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