Volume Prob

[cuxoni]

OK, thanks, I'll give that a try. I did measure everything before I put them in so that explains that. When I built it I used a sound card oscilloscope if that's any good?

[guest]

can you measure the voltage drop
across r69 and across r108

and use your soundcard scope
to measure the signal level
at r110 and at r96
they should be similar in level

im guessing that its either a bad transistor
or c16 or c29 arent working right

[cuxoni]

I would do this, but unfortunately I seem to have some other problems now. I might cry....

I was getting odd readings, so I repeated the previous tests and found the voltages to be way low. So I tested across J4 as a starting point an got 1.6v from pin 1 and 3.6v from pin 3. I unplugged the connector and the voltages are fine, so they're being lost somewhere, and I have no idea what to do. Sorry, this must be really annoying for you, me asking for help, making it worse and then needing more help! But if you have any ideas I'd appreciate it.

[cuxoni]

... unplugging IC9 makes the voltages return to normal. I'll try and trace it through ....

[guest]

ic9 is a common cause of shorts

did the volume problem go away with ic9 out

[cuxoni]

yes! With it out, depending on where the pots are set, it can no go way louder than the iPod was in comparison. Does that mean my IC9 is faulty?

[guest]

sounds like you found the problem
a very strange one indeed

what you might want to do
is measure the resistance to ground
from every pin on the ic9 socket
just to make sure that none of them are shorted that shouldnt be

[cuxoni]

Ok, I hope so! Here is what I see, I'm not sure what I should be seeing so, reading bottom left to right, then top left to right like the pictures on the right of this page

http://www.kpsec.freeuk.com/components/ic.htm

I see ...

1 - 70
2 - 344k
3 - 0
4 - 0
5 - 412k
6 - 0
7 - 35k
8 - 0
9 - 70
10 - 421k
11 - 0
12 - 0
13 - 390k
14 - 0
15 - 450k
16 - 600

[cuxoni]

sorry, I have that wrong! Too tired... reading it anti clockwise

1 - 70
2 - 344k
3 - 0
4 - 0
5 - 412k
6 - 0
7 - 35k
8 - 0
9 - 600
10 - 450k
11 - 0
12 - 390k
13 - 0
14 - 0
15 - 421k
16- 70

[guest]

power should be off when measuring resistance
it looks like it might have been on for those readings

[cuxoni]

No, I had it off. Just rechecked and it is correct, or at least my second version is, the first was mixed up.

[guest]

ok
0 ohms is really bad for all those traces
remove the microcontroller and check again
and if its still 0 ohms
then take a look at the traces and the socket
and look for shorts

you should still have ic9 out for these measurements as well

[cuxoni]

sorry, it was me being misleading. The zeros were no reading, apart from pin 8 which is actually 0 ohms. without the chip in its

1 - 8k
2- 400k
3 - no reading
4 - no reading
5 - 700k
6 - no reading
7 - 900k
8 - 0
9 - 8k
10 - 608k
11 - no reading
12 - no reading
13 - 808k
14 - no reading
15 - 1M
16 - no reading

[guest]

that looks good then

[cuxoni]

Excellent, so you think I should try replacing my IC9? Thanks.