IK5WWP
Neuling
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CPU hot and no connection to PC
« on: 10. February 2018, 15:43:38 »
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Strange chaotic behaviour testing my ui-board...
Jumper on P6
+5V on pin 28
Mini USB connected to the pc (tested with two different)
No white LCD, but sometime is flickering and sometime it's dark
Sometimes green led flickering or sometimes the red
Pc says "device not recognized"
Current absorbed is obout 500 mA and the mcu is a little hot...
What can it be? 
Thank you in advance, Lorenzo IK5WWP
Edit by Mod:
Please do not enter any threads with new problems but open a new one.
Thank you!
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| « Last Edit: 10. February 2018, 15:59:46 by DL8EBD » |
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IK5WWP
Neuling
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Re:CPU hot and no connection to PC
« Reply #1 on: 10. February 2018, 16:12:33 »
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Thank you Thomas.
Checked the cpu: the direction is right, no shorts between pins and no unsoldered pins.
Tried to remove the TXCO (I was thinking about to much hot during soldering), but no changes: still 500mA and the UI_3V_MCU is around 2V instead of 3V...
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IK5WWP
Neuling
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Ich liebe dieses Forum!
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Re:CPU hot and no connection to PC
« Reply #3 on: 10. February 2018, 16:36:36 »
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Double checked the cpu and the other components under the UI_3V_MCU: all right placed...
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| « Last Edit: 10. February 2018, 16:37:17 by IK5WWP » |
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DF6US
Neuling
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Re:CPU hot and no connection to PC
« Reply #4 on: 10. February 2018, 16:43:34 »
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I had a similar problem, MCU-regulator is hot and on MCU-side
2 V. In my way i have the wrong direction of the eeprom.
Look at
https://www.amateurfunk-sulingen.de/forum/attachments/IC7_Einbau.jpg
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ich verfolge dieses Forum schon länger und es ist
sehr hilfreich.
Aktuell bin ich am Zusammenbau des OVI40-UI
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DF5LI
alter Hase
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Ich liebe meinen SParrow !
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Re:CPU hot and no connection to PC
« Reply #5 on: 10. February 2018, 16:53:21 »
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I also have had an ui-board with no signs of life in the mcu. But it was nice warm!
The solution was no clock-signal, because the U5 oscillator was soldered in the wrong orientation. After turning the Clock oscillator-chip around, everything was running fine. I think, without a clock signal the mcu is only drawing current...
Check the 16 MHz at Pin 3 of U5 !
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| « Last Edit: 10. February 2018, 16:59:28 by DF5LI » |
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73, Harri
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IK5WWP
Neuling
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Re:CPU hot and no connection to PC
« Reply #6 on: 10. February 2018, 17:02:01 »
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Thank you all.
Checked and re-checked also the eprom.
Removed too, but the corrent absorption is still the same.
I really start to think that the cpu is burnt as Andreas said above...
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Paul C. H.
Neuling
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Re:CPU hot and no connection to PC
« Reply #7 on: 10. February 2018, 17:56:48 »
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My approach was to solder minimal component to test to CPU by DFU connection
not anything else.
CPU,
regulators and these 2R2 resistors, etc
16MHz TCXO, 32768k
only a few capacitors, for each DC rail 5V, 3V3_CPU, 3V3_analog
reset circuit
temporary wire to 'borrow' 5V from mini-USB when tested without RF board.
temporary wire to 'borrow' 3V3 from 3V3_CPU to 3V3_analog
tested DFU ok
solder additional components and re-test DFU after soldered every 10 items (approximately)
'roll-back' if I found DFU doesn't work / or incorrect current consumption.
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I understand only two German words.
with help of this forum, I often change from "g-e-t-l-o-s-t" to "g-e-l-ö-s-t".
what in front of me was feeling of "f-u-n-k", now it is a piece of almost working "f-u-n-k"
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IK5WWP
Neuling
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Ich liebe dieses Forum!
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Re:CPU hot and no connection to PC
« Reply #8 on: 10. February 2018, 18:16:58 »
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My approach was to solder minimal component to test to CPU by DFU connection
not anything else.
CPU,
regulators and these 2R2 resistors, etc
16MHz TCXO, 32768k
only a few capacitors, for each DC rail 5V, 3V3_CPU, 3V3_analog
reset circuit
temporary wire to 'borrow' 5V from mini-USB when tested without RF board.
temporary wire to 'borrow' 3V3 from 3V3_CPU to 3V3_analog
tested DFU ok
solder additional components and re-test DFU after soldered every 10 items (approximately)
'roll-back' if I found DFU doesn't work / or incorrect current consumption.
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I totally agree with you! I will surely follow this approach the nex time!
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IK5WWP
Neuling
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Re:CPU hot and no connection to PC
« Reply #9 on: 10. February 2018, 21:34:48 »
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I have found that also the the 3V regulator was burnt.
So, in the next days I will replace it.
Also the MCU will be replaced, because I am not shure if it is still good.
Before put on place the new MCU I will check again the 3V line to avoid any other component eventually damaged.
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IK5WWP
Neuling
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Ich liebe dieses Forum!
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Re:CPU hot and no connection to PC
« Reply #10 on: 15. February 2018, 11:33:31 »
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Today update.
Replaced 3V regulator and now I have a stable 3V and a stable white screen.
Not yet installed the new MCU because a I'm waiting it for tomorrow.
More news asap.
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IK5WWP
Neuling
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Ich liebe dieses Forum!
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Re:CPU hot and no connection to PC
« Reply #12 on: 15. February 2018, 11:57:07 »
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Stable 3V???? Before desoldering your MCU have a try if is still alive....
vy 73
Andreas
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Already desoldered because (as you rightly said) I don't trust the old warmed up MCU.
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IK5WWP
Neuling
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Ich liebe dieses Forum!
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Re:CPU hot and no connection to PC
« Reply #13 on: 16. February 2018, 16:04:21 »
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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...
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