I have recently assembled a K8055 kit, and the LD8 LED doesn’t flash 3 times when it is plugged in with a USB cable.
I have tried checking the PIC for power (by using a DVM to check pins 19 & 20) and the DVM reads 0.47 volts… What do I do from here? Is there a soldering problem?
Thanks to anyone who replies 
Is the Power LED LD11 also off?
First you have to check all the soldering joints.
Check also that all the microcircuits are in right position.
Power LED LD11 is on.
Soldering joints are checked, all good.
When you say microcircuits, do you mean the ICs?
Yes I meant all the ICs.
Especially check IC3 position.
It seems anyhow that there is +5V on the board.
You may next check the voltage over the capacitor C8.
You’ll find the C8 located next to the USB connector.
If there is +5V, then follow the trace on the PCB to the pin 20 of IC3 and check possible break in the trace.
I’ve just dismounted and remounted IC3, and there’s 3.18V coming out of pin 20.
Also, there’s 5 volts running across capacitor C8.
What can I do from this point? LD8 still isn’t flashing when I connect the USB cable, and LD11 remains on.
Is this voltage measured from the IC pin on the top side of the board?
If yes, then you have to check pin 20 voltage on the bottom side of the board too.
If there is +5V between pin 20 and ground (0V) points on the board, then there may be faulty connection inside the IC3 socket.
Remove the IC3 and check the contacts of the socket.
Here is the bottom side layout of the board.
The +5V trace is colored in red.
Thanks for the reply.
The bottom of IC3 also gives an output of 5V (measuring the bottom pins of IC3 19 and 20).
I’ve followed the red traces with respect to ground, all of them read 5V. There’s no break in the trace. All the measurements were taken from the bottom of the board.
Are there anymore diagnostics?
Is it now +5V on the top side on pin 20 of IC3 too?
Actually forget about that statement, after remounting the output voltage of pin20 is 5V.
Sorry about that.
[quote]after remounting the output voltage of pin20 is 5V.[/quote] OK. And now the pin20 is +5V both measured from the IC’s leg on the top side and on the bottom side?
But still not working?
Yes, LD8 doesn’t flash when a USB cable is connected. The output of pin 20 is 5V.
The traces in the diagram showed earlier also show no traces of break (as in the voltage at the corresponding pins are 5V)
If no flashes of LD8 are seen this indicates that the microcontroller IC3 program is not running.
Possible cause to this can be:
IC3 is defective.
Crystal oscillator circuit has wrong component. Check the capacitors C4 and C5 - should be 33pF and not visible breaks.
Check the crystal X1 soldering.
Measure the voltages on pins 9 and 10 to ground. - You can use the USB connector cover as a ground reference when measuring.
Voltage on pin 9 should be about 1.7V
Voltage on pin 10 should be about 2.2V
Pins 9 and 10 show the voltage that you mentioned.
There are no visible breaks on capacitors C4 and C5. What kind of voltage readings I should be able to obtain from them?
crystal X1 soldering is good.
How do I tell if IC3 is defective? How much is it to get a replacement for just IC3?
[quote]What kind of voltage readings I should be able to obtain from them[/quote]Same as from pins 9 and 10.
It seems the crystal oscillator is OK.
Maybe LD8 is misplaces (wrong polarity) on the board?
Now you may check in the Device Manager that one HID device is (or is not) added when you plug in the USB cable to the K8055?
The voltages are the same as pins 9 and 10. The LD8 is placed in the same orientation as LD11 (as in the cathode is placed in the hole with the line). However, it doesn’t show any voltage across it. There is no HID device that is added when I connect a USB cable to it.
OK.
Did you use only cored solder wire when soldering the parts?
Problems occur if you used any soldering liquid (flux) when soldering the parts.
See this thread: viewtopic.php?f=15&t=683
Yes, I have only used cored solder wire to do the soldering. Do you need any pictures to check whether the soldering is correct?
Also, how do you clean the PCB board (as mentioned in the thread that you suggested? )
There is no need to clean the board when only cored solder wire was used.
It seems that the IC3 is defective or there is something else wrong on the board.
It seems you have to send the card for checking to Velleman.
OK… 
It seems that the link doesn’t work. Could you pass me another one, or can I look for it myself? What am I expecting?
It is a link to the “Warranty for kits” page.
Now it is working:
velleman.eu/distributor/supp … country=be