SP3OSJ
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Re:Strange behavior
« Reply #15 on: 13. March 2021, 17:16:06 »
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Here is the path torn out.
PWM there is no GND.
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 track.JPG
« Last Edit: 13. March 2021, 17:20:11 by SP3OSJ » |
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WD8BXS
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Re:Strange behavior
« Reply #16 on: 13. March 2021, 18:03:38 »
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I am showing 1.49v on receive
Chuck
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De WD8BXS vy 73
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WD8BXS
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Re:Strange behavior
« Reply #17 on: 13. March 2021, 18:06:54 »
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Artur, I do not understand what you are showing me!!
Chuck
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De WD8BXS vy 73
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DB4PLE
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Re:Strange behavior
« Reply #18 on: 13. March 2021, 18:16:08 »
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Hi Chuck,
Side note: I think Artur wants to point out some strange looking area where the solder mask is scratched. That can lead to problems. I haven't looked up which pins these are but it indeed is something which normally looks better.
But now to the point: I am pretty sure, it is a hardware issue. And to finally verify, please remove R83 on the RF board, just as Artur suggested. And repeat the measurements at header pin 8 (RX, TX bias low, bias high value). If it still goes the wrong direction, well, the problem is between R83 and the processor or even in the processor (damaged DAC). If the removal corrects the voltage direction on pin 8, the problem is on the RF board, potentially U18 is damaged.
73
Danilo
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WD8BXS
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Re:Strange behavior
« Reply #19 on: 13. March 2021, 18:20:05 »
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WOW, with R83 removed, I have in excess of 3v at DAC on receive....
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De WD8BXS vy 73
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WD8BXS
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Re:Strange behavior
« Reply #20 on: 13. March 2021, 18:28:31 »
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I got this one in for repairs.
The user had broken the Step button off and tried to use tweezers to press the button.
The thing went dead.
I sued Stlink to revive it.
Now there is this issue!!
Thanks,
Chuck
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| « Last Edit: 13. March 2021, 18:40:20 by WD8BXS » |
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WD8BXS
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Re:Strange behavior
« Reply #21 on: 13. March 2021, 18:41:28 »
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OK, I have just taken the RF board from my radio and hooked it to the OV140
I am still getting the same results, Dac goes backward.
Chuck
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DB4PLE
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Re:Strange behavior
« Reply #22 on: 13. March 2021, 18:43:17 »
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Hi Chuck,
than I have good and bad news for you and the owner:
Most likely the processor has been damaged. Has happened before (I ruined 2 processors along the way. Most often it only affects few pins but then nothing can be done for these anymore). Only option is then to replace the processor.
That was the bad part. The good part comes now: go for a STM32H743 or STM32H753 instead when replacing. Much faster, less power hungry.
73
Danilo
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DB4PLE
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Re:Strange behavior
« Reply #23 on: 13. March 2021, 18:50:27 »
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Hi Chuck,
maybe you have some luck: I checked the schematics and PA5 is the DAC we have been looking at. But next to it (pin 41) is on pin 40 PA4 which is the volume DAC. Please see if changing the volume (AFG) has an impact on the measure value (or if there is a short between 40 and 41).
73
Danilo
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WD8BXS
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Re:Strange behavior
« Reply #24 on: 13. March 2021, 18:59:58 »
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Hi Danilo,
Changing the volume has no effect.
I do have a new MCU here but it is also the F7.
I will change it out.
Chuck
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WD8BXS
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Re:Strange behavior
« Reply #25 on: 13. March 2021, 20:37:06 »
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Installed new MCU.
Bootloader and firmware loaded via dfuse
When I hit power, I just get white screen.
Let go of power screen goes blank
I don't think the MCU is starting. I have voltage until I let go of the power button.
Back to the drawing board!!!
Chuck
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| « Last Edit: 13. March 2021, 21:29:32 by WD8BXS » |
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WD8BXS
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Re:Strange behavior
« Reply #26 on: 14. March 2021, 18:19:27 »
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All MCU pins seem OK
Will keep looking
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DB4PLE
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Re:Strange behavior
« Reply #27 on: 14. March 2021, 18:27:17 »
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Hi Chuck,
voltage goes away when letting go of the power button -> bootloader is not starting. Making sure power is not going away is one of the first things the bootloader does after early startup.
As the bootloader really does not have many requirements, it can also be that the processor is not configured as it should be.
For checking / fixing this, you need a ST Link and the STM32 Link program installed. Do a Chip Erase with STM32 Link, that brings everything to a default state. We have had the case that brand new MCU needed this as it seems you can get them also in other configurations from STM.
If you need more detailed instructions, just let us know.
73
Danilo
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| « Last Edit: 14. March 2021, 18:27:47 by DB4PLE » |
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WD8BXS
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Re:Strange behavior
« Reply #28 on: 14. March 2021, 19:44:30 »
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Hello Danilo,
Just finished mass erase and Option byte settings.
Loaded bootloader and firmware with dFuse.
Same results, white screen while holding power button.
SOOO Frustrating.
de CHuck
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De WD8BXS vy 73
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DB4PLE
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Re:Strange behavior
« Reply #29 on: 14. March 2021, 19:47:22 »
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Hi Chuck,
indeed. Not much we can do for you now, except keeping the fingers crossed and wishing you good luck. It should be nothing more or less than a solder bridge or a bad solder joint. You only have 144 to check 
73
Danilo
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