[marios_mar]

HI,
I just finished my Cmoy amp but unforunately it doesnt work. I checked the soldering and everything seems to be in place. What procedure should I follow to find what the problem is. Do you have any more particular tests I should do on each and every part of my amp.
I use the 2604 op amp and I tested with one 9V and later on two 9V batteries in line. I didn't get any sound at all from my headphones. The testing connections were good too. Next to the capacitors for line in and line out below them headphone out.
Please tell me whatever comes n your mind that could be wrong.
Remember , no sound at all!

Please help me, i am really dissapointed and sad...

 

[CarlJF]

May sound simple, but have you checked with a multimeter if the voltage are correctly splitted between the negative and positive rail ?

I'm not very experienced, but the first thing I would check is if the power line is right.

 

[stereth]

Check voltage at the V+ and V- pins of the opamp. Check also how well the voltage is split between ground the the positive and negative rails. On 9V, you should get +4.5V and -4.5V relative to ground. Using a multimeter, put one lead on ground and touch the other one to every component that should be connected to ground.

 

[marios_mar]

thanks for the replies!

I have tested the power circuit a million times and I get a perfect split. +/-4,5 Volts.

So power circuit problems are out of the question.

At first I hadn't soldered the outputs of the opamp anywhere because I left out the R5 resistor. Then I soldered them to the output and still I get no sound at all. Is it neccessary to solder the output to R4 resistance or is directly to output ok?
I will try soldering it first to R4 but I dont hope much itll work. Ill catch up later to say what happened but i its not what I just said either.



The test connections with the alligators are good since I connected the alligators of the cdp and those of the earphones and i get sound.
For ground I connected to the two bottom resistors.


Please keep your ideas coming.

 

[marios_mar]

ok I finished with all solderings and now all I can hear is very fain sound from the right channel only. Equivalent to like hearing from my PCDP at volume 1 out of 10 or something or maybe even less.
Now what ?
Please help!!!!!

 

[marios_mar]

it was a test cable connection problem that i dint hear anything from one channel. Now I hear from both channels only in a ridiculusously low level. My multimeter is completely out of adjustment for ohms and the adjustment wheel broke. I cant measure the resistors that the people at the store gave me the wrong pieces. Could it be that ?
Is it a common problem to hear low level sound?

Please everyone tell me what u think.
And you Tangent, what do you think?

 

[marios_mar]

i tested all the resistors now and saw a web page with the color codes and I got them all correct. So what could it be that I get faint sound. Please help me. Ive spent the whole afternoon fiddling around with it and cant find whats wrong.

 

[sTaTIx]

Could you re-check the values of your gain resistors (R3 and R4, I think) and post them here? Also, are you using a pot? Do you have it in a case yet?

 

[marios_mar]

No case, not pot.

I soldered the outputs directly to line out triple rows for the right channel and did the same for the right.
I think the left channel now sounds good as it should. Well it can't go that loud as with an integrated amp but much louder than without an amp directly from the discman phones out. I think that now all I need to do is figure out what is wrong with the right channel that still sounds so faint.
If i make the right channel sound at least as loud and as good as the left one then I am going to be celebrating. I will try tommorow.

Thanks to the people that are interested.

If you still have any ideas on what my problem could be please share.