Preamp Conord´s with some malfunctioning - diyAudio
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Old 14th June 2010, 10:45 PM   #1
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Default Preamp Conord´s with some malfunctioning

Hello!

I have a Conord´s Preamplifier... originally it doesn´t have the valves, (I´am sure they are 12ax7), and doesn´t work.
I resolder everything, I have change some caps, and the Fono, began to function.
However, I still having some troubles...

1) The filter, when I select 5K or 7K, the signal is attenuated drastically

2) Radio, Tv, and Aux input doesn´t amplify. (on the input have equal or less signal than the original)

3) When Master Volume is at minimum, I still having some sound...


If someone can give me a hand...

Thanks!!!

Guido
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Old 14th June 2010, 10:49 PM   #2
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Default In Spanish

Estoy necesitando ayuda con un preamplificador Conord´s, del cuál posteo algunas fotos, y diagramas a mano que hice hace algún tiempo (no se si se van a entender... cualquier cosa díganme y cuando me haga un ratito lo paso mas en limpio).

Originalmente no traía las válvulas, pero supongo todas deben ser 12Ax7.
Cuando me llegó no funcionaba nada, y luego de resoldar casi todo y cambiar algunos cables y capacitores secos comenzó a funcionar la salida de fono de manera estupenda. No obstante, sigue teniendo algunas fallas.

Les comento cuáles son:

El Filtro al ponerlo en 0k, la señal se escucha perfecto, en cambio cuando elijo 5k ó 7k la señal se atenúa drásticamente.

Las entradas de radio, tv y Auxiliar funcionan, pero dá la sensación que en lugar de preamplificar, me atenúan la señal.

Si el potenciómetro de volumen "master" lo llevo a cero, el sonido se atenúa, pero no se va completamente.


Si alguno me puede dar una mano...
Muchas Gracias!
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Old 14th June 2010, 10:50 PM   #3
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Default The Photos & diagram

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Old 14th June 2010, 10:53 PM   #4
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Maybe some part of the circuit is wrong, and I can´t see it!
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Old 14th June 2010, 11:00 PM   #5
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Quote:
Originally Posted by aguantesoda View Post
Здравствуйте!

У меня есть предусилитель Conord's ... Изначально в нём небыло ламп, (я уверен, что они 12AX7), а также не работает. Я перепаял все, поменял некоторыеконденсаторы, фоно, начал функционировать. Тем не менее, я все еще имею некоторые проблемы ...

1) фильтр, при выборе 5K или 7K, сигнал затухает резко

2) Входы радио, телевизор, а также вход Aux не усиливают. (Сигналы на входе те-же или ниже, чем в оригинале)

3) Когда регулятор громкости на минимуме, я все еще с какой-то звук ...

Если кто-нибудь может протянуть мне руку...

Спасибо!!!

Guido
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Old 16th June 2010, 01:51 AM   #6
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Jaja, It is in Russian ?
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Old 21st June 2010, 08:46 PM   #7
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nobody can help me?
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Old 22nd June 2010, 02:11 AM   #8
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I think Wavebourne was gently hinting that this is an English language only forum..

Seriously if you want help you need to give us a lot more detail..

Tell us what sort of test equipment you have.. A scope, meter, signal generator?

Edit: The 5K and 7K filters are supposed to chop off the response at 5kHz and 7kHz respectively, by modern standards this going to sound very dull.

Also what power amplifier do you drive with this pre-amp - it will not be happy driving modern solid state amps with low input impedances. Consider anything with less than 100K input impedance incompatible.

Did you trace out that schematic, parts of it look quite wrong to me, and even if it is correct it is impossible to follow.. Please redraw after looking at some good examples here..
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Last edited by kevinkr; 22nd June 2010 at 02:18 AM.
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Old 22nd June 2010, 06:39 AM   #9
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Quote:
Originally Posted by kevinkr View Post
I think Wavebourne was gently hinting that this is an English language only forum..
Sorry Wavebourne and kevinkr about that... my english language is very bad, and sometimes, I write THE SAME (not other thing) in spanish too, because in this forum there are a lot of people around the world who maybe can translate well if I´m wrong.


Returning to post, I have only a Tester ( resistance, voltage, current ).


Quote:
Originally Posted by kevinkr View Post
The 5K and 7K filters are supposed to chop off the response at 5kHz and 7kHz respectively, by modern standards this going to sound very dull.
Yes, I know, but in this case, it Attenuates the signal and no work like a filter (the sound falls down).

Quote:
Originally Posted by kevinkr View Post
Also what power amplifier do you drive with this pre-amp - it will not be happy driving modern solid state amps with low input impedances. Consider anything with less than 100K input impedance incompatible.
The power amp it´s ok; I use one with High impedance input.

Quote:
Originally Posted by kevinkr View Post
Did you trace out that schematic, parts of it look quite wrong to me, and even if it is correct it is impossible to follow.. Please redraw after looking at some good examples here
I follow a book of 50´ to draw it; because draw this ( for me ) in "Workbench" software is very difficult.


Thanks for the reply kevinkr.
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Old 22nd June 2010, 08:36 AM   #10
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Quote:
Originally Posted by aguantesoda View Post
Sorry Wavebourne and kevinkr about that... my english language is very bad, and sometimes, I write THE SAME (not other thing) in spanish too, because in this forum there are a lot of people around the world who maybe can translate well if I´m wrong.
No problems at all; I was thinking may be somebody Russian can help you as well...
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