IK5WWP
Neuling
 Offline
Posts: 25
Ich liebe dieses Forum!
|
 |
Re:CPU hot and no connection to PC
« Reply #15 on: 16. February 2018, 16:04:21 »
|
|
Replaced the MCU.
Nothing to do: for a little while low absorption then after a few second the currente rise up to 500mA and there ia short circuit between UI_3V_MCU and GND.
Removed components under UI_3V_MCU like IC1, IC12, IC5, IC7 and the short is still present.
Removed MCU the short is gone.
Resoldered the MCU, no short for a few seconds then again 500mA of absorption.
I'm not luky with MCU?
I'm sure there are non solder joint between pins of the MCU and I don't want to desolder the MCU for the third time. The risk is that same pads go away and so, after, the entire board will be a piece of junk...
|
|
 Logged
|
|
|
|
DL8EBD
positron
Urgestein
Offline
Posts: 1926
|
|
Re:CPU hot and no connection to PC
« Reply #16 on: 16. February 2018, 17:11:40 »
|
|
that's not good!
please show us a (high resolution) picture from your board.
|
|
Logged
|
bitte keine technische Fragen oder Diskussionen via PN, dafür ist das Forum da.
vy73
Thomas
|
|
|
|
|
|
|
IK5WWP
Neuling
Offline
Posts: 25
Ich liebe dieses Forum!
|
|
Re:CPU hot and no connection to PC
« Reply #19 on: 23. February 2018, 15:55:31 »
|
|
Update of 23/02/2018
Soldered a new MCU and tested the resistance between UI_3v_MCU and ground: about 1.3 Kohm (Ok, Before was only about 10 ohm)
Note: any active and passive components between UI_3v_MCU and ground was previously removed: only the MCU.
Now step by step I will re-put in place the components removed and every step I'll check the resistance.
Just a few steps a day: I don't want to make another roast-MCU!
|
| « Last Edit: 23. February 2018, 15:55:58 by IK5WWP » |
Logged
|
|
|
|
|
|
IK5WWP
Neuling
Offline
Posts: 25
Ich liebe dieses Forum!
|
|
Re:CPU hot and no connection to PC
« Reply #21 on: 24. February 2018, 13:35:28 »
|
|
The first thing I would test is if any short-circuits are between MCU pins which are side by side. You can take such very precise "peaks" like they are used at dentists. Connect them to a DVM in "short circuit test mode" and test all pins for shorts to their neigbours.
vy 73
Andreas
|
|
Thank you for this suggestion: before giving current I'll surely do also this test!
73, Lorenzo
|
|
Logged
|
|
|
|
|
|
IK5WWP
Neuling
Offline
Posts: 25
Ich liebe dieses Forum!
|
|
Re:CPU hot and no connection to PC
« Reply #23 on: 28. February 2018, 17:58:07 »
|
|
"Dentist test" done and passed ok.
Now ahead step by step.
A little step a time.
|
|
Logged
|
|
|
|
IK5WWP
Neuling
Offline
Posts: 25
Ich liebe dieses Forum!
|
|
Re:CPU hot and no connection to PC
« Reply #24 on: 03. March 2018, 10:53:46 »
|
|
Ok!
Finally I have a working MCU.
It is recognized by the pc and I can upload bootloader and firmware, but...
Removed jumper on P6, removed the cable on DFU port, given +5V, I can only see a white screen.
After a few seconds the screen light became not stable, but if I press and keep depressed the power on/off button the white screen become stable, so I believe it is a software problem and not an hardware problem.
It's time to buy an ST-LINK?
|
|
Logged
|
|
|
|
|
|
IK5WWP
Neuling
Offline
Posts: 25
Ich liebe dieses Forum!
|
|
Re:CPU hot and no connection to PC
« Reply #26 on: 03. March 2018, 11:13:05 »
|
|
Hi Andreas!
Thank you for your prompt answer.
You sent me a populated LCD after the first expedition went to Portugal, do you remember?
Have I to check something in particular on the LCD board?
|
|
Logged
|
|
|
|
|
|
IK5WWP
Neuling
Offline
Posts: 25
Ich liebe dieses Forum!
|
|
Re:CPU hot and no connection to PC
« Reply #28 on: 03. March 2018, 15:00:07 »
|
|
Disassembled LCD, checked all solder joint, cleaned accurately all the fluxant.
Now the white screen is stable, the current absorption is about 70mA constant, but only white screen.
No particular hot spot: checked with a thermal camera: max temperature about 25° C on the MCU and on the 3.3V regulator
What can I do now?
|
| « Last Edit: 03. March 2018, 15:27:09 by IK5WWP » |
Logged
|
|
|
|
DF5LI
alter Hase
Offline
Posts: 371
Ich liebe meinen SParrow !
|
|
Re:CPU hot and no connection to PC
« Reply #29 on: 03. March 2018, 15:32:08 »
|
|
Ich hatte bei 2 neugebauten ui-Boards (V.04 und V.06) ein ähnliches Problem. Nach dem Flashen mit JP6 und dfuSe schien nach der Anzeige von dfuSe alles ok zu sein, aber nach dem Einschalten der Boards war der Bildschirm auch nur weiß. Abhilfe brachte ein 2. Flashen des Bootloaders, danach lief alles prima!
Starte mal einen 2. Versuch !
|
|
Logged
|
73, Harri
|
|
|
Author
