MK-312 BT some questions

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LeLuc
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MK-312 BT some questions

Unread post by LeLuc »

Hello guys,

i´m new in this forum and from germany :)

I have some problems with my MK-312 rebuild. Today i finished the second one without success. I didn´t get a normal failure 20 rather my LCD Display shows in the first row only white pixels. It also make some different effect when i flash the hellofriend.bin and electrodesready.bin firmware. Sometimes the backlight of the LCD goes on and off. Do somebody of you have this problem also?
I´m an eletrical engineer but in high votage inverters not in microelectronic. It hurt my honor a little bit that i didn´t get it going. :?

Hope some guys can help me. And yes, for the other people, when i´ve found the problem i also can build more of them for you guys :)

See you,
Luca



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lawman
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Re: MK-312 BT some questions

Unread post by lawman »

Try re-flowing all your solder joints. What lenght is your ribbon cable? Really long ones causes issues. Did you build 1.3 or 1.4?
Be sure all the chips are seated in their sockets firmly.

LeLuc
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Re: MK-312 BT some questions

Unread post by LeLuc »

I have already soldered a completely new PCB so I think there should be no more weak solder points. Yesterday I have also measured some signal with the oscilloscope and realized that the DAC didn´t make some PWM output. Also there is no measurable signal at the 0,5 Ohm resistor.
The ribbon cable is short so this shouldn´t be the problem. In my opinion the firmware is maybe not flashed correctly on the atmega. Could this be a possible reason? I´ve did this with avrdude and a Arduino Uno.
Maybe you have some more ideas. I really didn´t know what to do next…

LeLuc
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Re: MK-312 BT some questions

Unread post by LeLuc »

For the completeness I didn´t use IRL520N rather LU120N because mouser didn´t had the IRL520N in stock for a while. But this shouldn´t be a problem because there are nearly the same mosfets.
I also tried to use the internal oscillator but this didn´t work at all. Do you have an idea what to do next?
Thank you very much for your help.

LeLuc
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Re: MK-312 BT some questions

Unread post by LeLuc »

Hi guys,
I´ve build now the 3rd unit an still have the same problem. I only use other MOSFETs istead of the IRL520N.

Maybe someone have a answer to my questions. I dont know how to go on.

Thank you.

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lawman
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Re: MK-312 BT some questions

Unread post by lawman »

LeLuc, I have been trying to reply to you but something has beem amiss with me being able to use this forum. First since you are in Germany you have a very good parts house there. Conrad electronics is based in Germany and has the IRL520n in stock, I would change those out. This box is a bit sensitive to parts substitutions. There is a bit of difference in the specs and it might be enough to cause the Atmega not to respond correctly. Secondly there are a few of the firmware loads that have issues. Here is an invite to Joannes Discord server.
https://discord.gg/HbGKY2t
There is a lot of info there and people a lot smarter than me. Go to the DIY control boxes channel and up to the pinned messages. Scroll down and about in the middle there is a link to download t002_bootloader.bin. I will vouch for that one has good. From the info you have given my guess is it either the mosfet substitution or the firmware load. Be sure to set the fuses first.

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