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
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
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!
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!
The Photos & diagram
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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..
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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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 ).
Yes, I know, but in this case, it Attenuates the signal and no work like a filter (the sound falls down).
The power amp it´s ok; I use one with High impedance input.
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.
No problems at all; I was thinking may be somebody Russian can help you as well...
Check to make sure those replacement caps you installed are actually the correct value particularly in the filter circuit.
I would try to locate the actual schematic for this pre-amp, although it might be impossible..
I would try to locate the actual schematic for this pre-amp, although it might be impossible..
I cannot locate the original schematic, but I found and error in the one I have do. This is correct (is all I have).
Attachments
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I´m sure the problem is near Master Volume. Maybe is missing a ground, but I don´t know; I don´t understand how it work...
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