Electronics > Repair
Repair Help for APC UPS BR1500G - F06 error (FIXED!!)
Vovk_Z:
That's good you don't stop and now even can repair your own damage :)
I'm strugling to write "we told you to look into that output circuit carefully earlier". :)
It could be dangerous to microprocessor output pin when you apply external voltage to it without current limitting (like 100 R resistor in series). I would better cut a control wire to do it safe for microprocessor. Or I would just check a control voltage if it present or not.
Are you sure that relay RY14 has to move at your tests?
RLP:
OK that is fascinating indeed. Great diagnosis!
My general feeling is that that particular GPIO on the microcontroller is probably dead - I have seen it happen. Usually it happens where a pin is exposed to some transient, so it's hard to guess why it would happen in this case. But definitely in the realm of plausibility. The fact that it thinks the relay is welded seems like proof that it 'should' be outputting a signal on that GPIO pin to control it. Although... I suppose there is still a tiny possibility that something else is wrong (e.g. voltage measurements) that is causing it to not switch when it actually should. But I think the voltage measurements must be correct: you said it outputs 120V (hence output measurement is probably correct) and the display shows input voltage correctly. Can the display show output voltage as well, to verify that...?
Replacing the microcontroller should be feasible if you can solder it, because you can almost certainly dump the firmware from the existing microcontroller. The STs are relatively simple to do this on: it's documented by ST, but basically something along the lines of setting the boot mode with BOOT0 and BOOT1 pins so that it runs the internal factory bootloader, and then powering it up and connecting to UART0 with something like a USB to serial adapter, and using ST's flash loader program to dump the firmware. Same process for programming a new chip. And they are usually unlocked on APC products so no read protection to stop you doing this!
fmashockie:
--- Quote from: Vovk_Z on September 02, 2023, 07:18:42 am ---That's good you don't stop and now even can repair your own damage :)
I'm strugling to write "we told you to look into that output circuit carefully earlier". :)
It could be dangerous to microprocessor output pin when you apply external voltage to it without current limitting (like 100 R resistor in series). I would better cut a control wire to do it safe for microprocessor. Or I would just check a control voltage if it present or not.
Are you sure that relay RY14 has to move at your tests?
--- End quote ---
I know Vovk ;D! You and RLP were definitely right on the money from the start! Thank you for that tip about current limiting when applying external voltage to micro. I really am in new territory here. My experience troubleshooting micros is a bit slim. I did limit the current from my power supply. And I tested the micro prior to running this experiment to see if any voltage was being applied to signal RY14 - it was 0V throughout the start-up process. Having trouble understanding your last question. But I greatly appreciate your help!
--- Quote from: RLP on September 02, 2023, 11:25:27 am ---Can the display show output voltage as well, to verify that...?
--- End quote ---
Yep the display can show input and output voltage. And from what I measured, both of them are very accurate.
--- Quote from: RLP on September 02, 2023, 11:25:27 am ---Replacing the microcontroller should be feasible if you can solder it, because you can almost certainly dump the firmware from the existing microcontroller. The STs are relatively simple to do this on: it's documented by ST, but basically something along the lines of setting the boot mode with BOOT0 and BOOT1 pins so that it runs the internal factory bootloader, and then powering it up and connecting to UART0 with something like a USB to serial adapter, and using ST's flash loader program to dump the firmware. Same process for programming a new chip. And they are usually unlocked on APC products so no read protection to stop you doing this!
--- End quote ---
So I'm not worried about desoldering this micro and soldering a new one. I'm confident in my abilities to do that successfully (I like to use ChipQuik removal alloy. Works really well and don't have to worry about applying too much heat like with hotair). But reprogramming the chip and extracting the firmware is definitely new territory for me. I've always wanted to learn how. Especially because I've run into other repairs where having this experience would have allowed me to complete them successfully!! Do you have any resources/procedures you can share to get started? Do I need a USB programmer to do this (I'd need to purchase one if so). Thank you so much RLP for everything so far!!
fmashockie:
Well guys I'm pretty excited to give 'flashing' this STM32F1xx micro a try! While I am still entertaining the possibility the micro is fine and there's something else wrong with the board, I'm leaning more towards an issue with the micro itself. So I've done some research on how to flash this chip. RLP you were pretty much spot on about how to flash the chip as far as I can tell. ST has a ton of great resources for how to do this. I started with reading ST Application Note 2606 (https://www.st.com/resource/en/application_note/an2606-stm32-microcontroller-system-memory-boot-mode-stmicroelectronics.pdf).
The STM32F1 appears to be very easy to work with. It is compatible with UART connection. So I then bought one of these FTDI USB 2.0 to UART cable to interface with the micro (data sheet here https://ftdichip.com/wp-content/uploads/2020/08/DS_C232HD_UART_CABLE.pdf
Next it seems the ST also offers free software to download that will allow me to enable the bootloader function and flash the chip. It's called the STM32CubeMx (info here https://www.st.com/en/development-tools/stm32cubemx.html).
I will also order a replacement micro as well to perform the flash (man this repair cost for this is starting to add up ;D)
But anyway, based on all that, does it sound like I am on the right track?? Like I said, this is all really new to me so if someone could check my thought process here, I would greatly appreciate it!!! Really excited to give this a try!!
RLP:
Yeah that sounds good to me. I've only used the older software myself (https://www.st.com/en/development-tools/flasher-stm32.html) but I assume the new Cube software will have all the same functionality in there somewhere. Good luck!
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