Topic : broken RLink repair / diagnosis

Forum : ST7/STM8

Original Post
Post Information Post
June 9, 2010 - 5:00pm
Guest

Hi,

Yesterday while my board and RLink were running, I accidentally short-circuited a ground clip from my oscilloscope somewhere on the board. After disconnecting and reconnecting power, I found that my hardware seems to be working OK but the RLink module no longer enumerates. When the USB cable is connected, the "pwr" LED turns on but not "busy" (like it used to do). The operating system on this computer (Windows XP Pro, 32-bit) does not sense the USB device at all (no sound plays and USBDevView - http://www.nirsoft.net/utils/usb_devices_view.html - does not list it). However, when I attach a different RLink, everything works OK.

I found this other thread about troubleshooting:
http://raisonance-forum.xsalto.com/viewtopic.php?id=2141

measurements
Here is what I measured on the broken RLink
(Used USB shield as ground reference, connected USB to PC, left programming ribbon cable disconnected)
1) 4.75V
2) 4.45V
3) 0.50V
4) 0.75V
5) 0.95V DC (<1Hz)

What do you think may be the problem? I would like to repair this RLink, if possible. Thanks in advance!

Update: I now realize that the microcontroller gets very hot :( Could I order a replacement of this part? I could send you the old one, I think.
Replies
Post Information Post
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June 9, 2010 - 6:12pm
Raisonance Support Team

Hi,

From what you describe I think that indeed the ST7 is burned, but there might be other parts that suffered during the shortcut. (which ADP were you using? Does the ST7 get hot if you remove it?)

So changing the ST7 alone is not guaranteed to solve the problem, and it would probably cost you more in shipping than buying a new RLink from your local distributor. (we are in France...) And also these components are not easy to unsolder without damaging the PCB.

Was it a RLink Pro or Standard?

Best Regards,

Vincent
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June 10, 2010 - 5:49pm
Guest

Vincent,

Thanks for your fast reply. I was debugging an STM8S with the ADP for SWIM (I think this is called ADP SWP 0.050). J6, J7, and J8 were open/off. J5 was set to SWIM_DATA. I disconnected the ADP when troubleshooting the RLink, so yes, the ST7 gets hot even when no debugging adapters are connected (just USB to PC). This is an RLink Standard.

-JQ