HI, i finish today my K8055 but when i connect it to the pc then it works after 15 seconds the connection lost and i can’t reconnect it. When i wait 10 minutes and i put it again to the pc then it works again 15 sec and then the connection lost. Is any component broken?
Is the power LED LD11 lit when the device is not working after 15 seconds?
If the LED is turned off, this may indicate that the card is drawing too high current from the USB bus. The PC disconnects the card.
The cause may be assembly error or defective component on the board.
Please check the right position of the operational amplifier IC2.
[quote=“VEL255”]Is the power LED LD11 lit when the device is not working after 15 seconds?
If the LED is turned off, this may indicate that the card is drawing too high current from the USB bus. The PC disconnects the card.
[/quote]
No is always ON. But when i reconnect it after the connection Lost then the LD8 doesent turn off.
[quote=“VEL255”]The cause may be assembly error or defective component on the board.
Please check the right position of the operational amplifier IC2
[/quote]
It is on the right position.
Now after 24 Hours break i test it again and it works 20 minutes ( it could have been longer works but i disconnect it ) but when i disconnect it from the pc and reconnect it then the problem is the same…
Is a Capacitor broken?
VEL255 Do u speak German?
The cause to the problem may be a defective component:
microcontroller IC3, crystal X1 or capacitor C4, C5 or C6.
The problem may be in the PC too.
Can you test the card in other PC?
[quote]VEL255 Do u speak German?[/quote]Sorry, no.
I have 2 k8055. The second k8055 works perfect with my PC. I change the IC3 from the other k8055 and it isn`t the IC3. How can i check the crystal x1? And how can i check the capacitor?
So the IC3 is OK.
There is no easy way to check the crystal. The only way is to change it.
You can only check the capacitors visually: No visible damages (cracks) and soldering OK.
i change the crystal and it´s still the same. capacitor are ok. what can i do? 
This is very strange case.
Please check the right polarity of C8.
Maybe there is something wrong with the IC3 socket or soldering.
If you have a multimeter you may check the voltage on each pin of the IC3 and compare with the working K8055 card.
[quote=“VEL255”]This is very strange case.
Please check the right polarity of C8.
[/quote]
It is on the right polarity.
Soldering is ok
Hm i try but now the LD8 doesent turn off it is always on i get now no USB connection. 
Does the LED LD8 flash two times and then stay on?
This indicates that the microcontroller starts to run but there is problem to get the USB connection.
You can check the voltages on the IC3 pins in this case.
Check if there is any difference compared to the working K8055 card.
Especially check the pins 14, 15 and 16.
Also pins 9 and 10.
Also check the R35 value (1k5) and USB connector soldering.
The first time when i connect it with the Usb Cable the LD8 flash 2 times and then it goes off. When i try to Connect it with delphi it says Card not found. And when i now reconnect the USB Cable then the LD8 flash 2 times and stay on.
I dont know how to check this.
Soldering and resistor are right.
You need a multimeter (DVM) to do the measurements.
Just checking:
- You have already changed the IC3 from the working K8055 to this defective one and the problem persists?
- Also you have changed the crystal X1.
Have you tried with other USB cable?
You can return the board to check / repair.
i replaced now all capacitor and it dont work and the usb cable and now i can’t soldering the resistor R25 there is no copper to hold it. 
I send it back to velleman