Volume Prob

[cuxoni]

Hi,

First post from me, so hello everyone....I have a question if I may...

I just completed my x0xb0x kit and while all is working fine the volume pot is faulty. I have another one in the post but until then is there anything I can do to carry on using it? By that I mean short it out with a bit of wire or a resistor?

Thanks,

Mark

[guest]

yes
you should be able to short it out
but it would best to remove it first
before doing that

does it sound bad when the volume is full up
if so
it could be a bad solder joint on the pot

[cuxoni]

Thanks, it just doesn't work unless I get it in just the right position. The joint seems fine but I'll recheck. If I was to short it out is it OK to do with just wire on it's own?

[guest]

its alright to do
as long as you keep the volume full up

[cuxoni]

I replaced it with a temporary pot of the same value until I get the replacement but thanks anyway. Still I have some issues though. How loud should it be at full volume as a line input? When I plug it into my soundcard with no gain it's about 1/3rd of the way up the decibel indicator?

Also, the headphone output makes a loud constant buzzing noise. Does anybody have any ideas? Could this somehow be related? Other than this it works fine.

Thanks.

[guest]

the pot was probably fine
there is something wrong
with one of the coupling capacitors
or the mixer section

compare the dc voltages from the vca and mixer
to the ones given in the voltage map post

[cuxoni]

Thanks. I think it was a faulty pot but you're right there was a problem elsewhere too. I found that IC14 had a bad connection. That's sorted out the headphone issue and possibly made the line out a bit louder too. Comparatively the headphone out and main out are more or less the same, the headphone is slightly louder but not much. The peak is about -15db. Is that too quiet still? I checked voltages but couldn't find anything. I can recheck it but I'm not sure if there's anything wrong or if this is normal. Thanks for your help.

[guest]

the output should be close to 0db
im guessing there are some resistors
that arent the right values
in the mixer section

[cuxoni]

OK, thanks a lot for your help, I'll have a thorough recheck and see what I find.

[cuxoni]

I rechecked all the resistor values and voltages in the mixer section and they seem to be as expected. Is there any voltages or anything to check on the I/O board? Or might there be a problem in some other area of the main board? If not I can probably live with the fact it's a bit quiet but it'd be nice to know why. Thanks again.

[guest]

what is the volume level
directly at the volume pot
its possible the vca isnt quite right
it should be really loud there

[cuxoni]

Sorry, I don't quite follow and don't want to damage anything by doing something stupid! Do you mean if I bypass the volume pot completely taking the positive feed going to it and sending it to my soundcard what is the db level I find there?

[guest]

i was suggesting taking a feed
directly off the top lead of the volume pot
im guessing it will probably too hot for your soundcard
but if it isnt
then that would tell us the problem is at the vca or before it

[cuxoni]

Ah, I understand, I'll check it out. Thanks.

[cuxoni]

Hi, sorry for the long delay, I've been waiting to get chance to have a good look at this. I opened it up and checked the decibel levels. Unless I'm misunderstanding something this is what I did and saw:

All this was done with the volume pot up to full.

I checked the volume level at the main out: -18 db
checked same at headphone out: -13 db

using bulldog clip leads grounded the jack lead going in to sound card, put the other part of the jack across the 3 pins of the volume pot:

pin nearest edge of board nothing happens (guess its ground?)
middle pin and innermost pin both -22db

Sorry if I'm being a bit thick with this, thought 'hey, its a bit of soldering, how hard can it be!'. Guess I was wrong! I'm really stuck so appreciate all the help.