It appears that the Dim and Gnd legs are on the same copper so the chip needs to be moved to the left a bit. I'm thinking that the Dim pin low turns it off. No connection may turn it off too, but it may flash on for a bit at startup.

What would I do? Do everything on a breadboard. They do make small grasping clips that can grab ahold of those small chip pins too.

http://www.ebay.com/itm/10-pcs-Small-Test-Clip-for-Multimeter-Lead-Wire-Kit-Repair-Tool-5-color-/230998564086?pt=LH_DefaultDomain_0&hash=item35c8965cf6

Soldering should be a one time thing based on the limitations I have seen for many components. Radio Shack has a nice battery operated iron that I use for delicate soldering jobs.

 

What is the size of that cap? It looks huge.

I would take another try at that PC board.

I can post some artwork if you have access to a laser printer or photo lab.

 

Welcome back after a brake. I built another circuit. Two channels on a board. It works ok only with a small current. When I use higher value of Rs, it gets hot and led start blinking faster and faster. I stop it before its too late.
Even with 350mA chip is hot. But its working continuously.
I attach the pcb.

 

Which is the bottom view an which top looking down?


For starters IC1 and IC2 are both configured differently. You do not have pin 2 grounded on IC1 and it should be.

The large tab is a heat sink and as far as I am aware should not be grounded.


Look at the artwork I posted above, it works.

 

Red is top. Pin 2 is connected with a pad.

 

What side is the PT4115 mounted? On the top?

 

yes, on the top

 

With 350mA it works ok. With Rs= 0.22 I should get about 0.45mA, but Im getting over 0.55. Additionally, it slowly raises... up to 0.8mA and maybe it would go up. But Im stoping it. And it takes about 5 min.

And about a DIM. I connected witha voltage supply, and it works more less. But how to turn of a led? I mean, with a DIM...

 

Try putting Dim to common instead of no connection. What does it do then?

You should be able to put it high or low with a jumper.

 

Try putting Dim to common instead of no connection. What does it do then?

You should be able to put it high or low with a jumper.

That is not it. I let mine float and it is fine.

 

It looks to me like IC1 is correct. I did not look that closely at IC2. What I would do is to remove all the components for IC2.

I am attaching the pinout for the PT4225 oriented the way you have it o the board in case others want to take a look.

And it is a lot easier if you put your images inline

 

You should also post your actual work so folks can look for solder bridges and such.

 

And are you certain your diodes are not shorted?

 

Im gonna post some pics later. The diodes are not shorted. If I connect to the 1st one the current is stable about 350mA. When I connect to the other one, the current is ok in the beginning, but after a few seconds it slowly raises...
The capacitors I use are 100uF tantal and 4.7uF

 

If IC1 circuit is connected but IC2 is not connected then IC1 circuit works as expected?