Easy Vibe (oh no!! again)

[arma61]

Hi guys

So just facing this challange , I'm using the R.G' layout, the one marked 2001-2006 on the bottom of the board

http://www.geofex.com/PCB_layouts/Layouts/easyvibe.pdf

I've already checked for solder bridges, components orientation and so on, everything looks goods, though I'll check them again as some areas on the board are very tight.

And I'll post voltages if required, but first let me ask these questions as may be there could be some "easy-fix", (you know "check junction R?/C?, that's were the problem should be") so I can skip the "voltages" part (I know... I'm a lazy boy, also I don't trust my cheapo DMM too much..)

I did search the forum but it seems I cannot find an answer to my problems.

What is happening is this, as soon as I give power to the circuit the 4 LEDs, those facing the 4 LDRs, start blinking/flashing, increasingly from off to on, for few seconds, regardless of the pots setting, then they stay always on, no flashing anymore.

Also the 2 LEDs on the far left side of the board, are off, neither blinking, but I've found in this forum discrepancies in reply to this as someone says they should be on and other say they should not be on. Who's right?



Thx m8,
Ciao
Armando

[R.G.]

Voltages.

[arma61]

ok lazy boy is back

so I start to take voltages and suddenly stop as it seems I'm missing the Bias Rail (I don't know what I'm talking about  just red it on a post here) , so I cannot find any point at ~ half of supply voltage.

Here are the reading on IC1

1. 8.28
2. 8.07
3. 7.18
4. 0.00
5. 8.20
6. 8.28
7. 8.30
8. 8.95

I'm sure 4. is ok 

so which is the group of components generating the bias ? I'm not so good in reading shematics, specially those draught by hand

are the 2 x 470uf involved in this ? I didn't have brand new so I took them out from an old project, could they be faulty ?

I've checked again for bridge but, if there's one, must be sneak!

in the mean time have I fryed my ICs (TL072) ?

so, did I get the problem (bias)?

Do you need anyway the other ICs voltage reading (ahhh, lazy boy again! the fact is that I work in my kitchen table, so everytime I have to take off everything I need from the shelves and put on the table, then I have to clear the table away, put all the stuff on the shelves and so on.......  )

Thx 4 help
Ciao
Armando

[arma61]

ok m8s I feel terribly sorry!! I have no words to explain my frame of mind now!

I've found the problem, I just checked again and I've found that I had the 2 LEDs at the bottom of the board backwards!. When installing all the components on the board yesterday I had a doubt about the way I installed the LEDs (everytime I have this doubt! Anode/Cathode which is which, cannot remember it, just like at school 30 years ago ). So I checked on the net, print out a page with a picture of a LED and compared with my board, and, as I though, my LEDs were backwards, so I swapped them; all of them! just to find now those 2 LEDs were installed in the right way.

so I apologise for such a stupid post.

feel free to revile on me, I deserve it. 

I wish I could remove this post.



I'm going now to test it with audio, but this is another story......



Cheers m8s
Armando

[R.G.]

You have nothing to be embarassed about. You had a problem and didn't think you could go any further. I sent you one word, you took it, guessed the problem (bias) immediately, and then went directly to the parts which were giving you the problem (those LEDs generate the bias voltage) and then you fixed it.

What's wrong with that? A complete fix from a single word hint? That's good!

[arma61]

looking at it in that way sounds good! thx R.G

to be honest as I hit "show new replies to your post" and saw your name on first reply I say to myself "ok, this is going to work at the end!", indeed just one word and problem solved!

By the way also the audio is working, so now I only need to give it a good house.

thx & have a nice day.
Armando