Rod Elliot P06 Riaa problem

[gchrist]

I have built the p06 RIAA preamplifier from Rod Elliot. I cannot get any sound from it. I can only hear a very vague musical signal when the preamp is turned full volume. I have used metal film caps in place of polysterene ones. Do you thing that this may be a problem? What is the diffrenec between MKT caps that have a cubical constructions and those that have the traditional look?

Can I use MKT capacitors for bupass reasons in place of ceramic ones?

Thank you

[peranders]

If you have bought pcb's from Rod you can always surf to his forum and get help there from him in person.
http://www.instantboard.com/users/rode/

[analog_sa]

If it doesn't work - your wiring is wrong. Forget about the caps.

[gchrist]

Ok,

I will check today afternoon again. If it is a wiring mistake I should have had some smoke!!!

I presume that maybe I have put a resistor with the wrong value somewhere. I do get an output voltage but it is very very small. You can just hear it.

Thanks for your help.

George

[peranders]

Originally posted by gchrist
Ok, I will check today afternoon again. If it is a wiring mistake I should have had some smoke!!!

Haven't you ever connected wrong _without_ smoke?

[gchrist]

I am relatively new in electronics. I have constructed an AKSA 55W and the BOSOZ with no mistakes. I do not have mauch experience so maybe if you connect something wrong it does not blow up or smoke. It just misfunctions. I will let you know of my findings.

If someone knows anything about the caps questions I stated earlier I would like to see their comments.

Thanks again,

without smoke

George

[Eva]

You probably have the signal path interrupted or shorted to ground somewhere. It may be also due to an interrupted or shorted to ground supply line

Mistakes are not likely to produce smoke in small signal circuits [fortunately]

[Tube_Dude]

Originally posted by gchrist


If someone knows anything about the caps questions I stated earlier I would like to see their comments.

Thanks again,

without smoke

George

HI George

What is the diffrenec between MKT caps that have a cubical constructions and those that have the traditional look?

If they are made from the some material...the difference will be only cosmetic .
But in general the cubical construction gives them more resistance against humidity and the cleaning fluids used to clean the boards.

Can I use MKT capacitors for bupass reasons in place of ceramic ones?

It depends...MKT are better in the audio band (but no so good as poplypropilene or polistyrene)...the ceramics are better for power supply bypassing in the VHF region (very high frequencies)

Regards

[gchrist]

I may have found the problem. Some resistors from Digikey measure differently than what the colour stripes refer to. Instead of measuring 100K I only measure 80K. This happens with the resistors I used in the circuit but also on all of the spare resistors that were left over. The same happens with a 180K resistor.

I do not understand why this is happening. I will buy today new resistors and I will let you know.

Thanks
George

[Tube_Dude]

Originally posted by gchrist
I may have found the problem. Some resistors from Digikey measure differently than what the colour stripes refer to. Instead of measuring 100K I only measure 80K. This happens with the resistors I used in the circuit but also on all of the spare resistors that were left over. The same happens with a 180K resistor.

Hi George


I suspect that the difference come from your multimeter, not from the resistors..