Jyetech AVR digital oscilloscope DIY KIT — trying to fix it – part 2

Maybe you remember my last post about the Jyetech oscilloscope and it’s weird behaviour. Not all of them are strange, as the free replacement DIY KIT I received from them works fine. At that time I suspected a sick ATmega64 cpu and had all sorts of plans to detect what components might be bad.

Long story short, I scrapped all of it and just replaced the ATmega64. Using ChipQuik it was as easy as it should be, a no brainer.

Jyetech - replaced ATmega64

Here’s a video:

I had already posted the update sequence using avrdude, but here it comes again. I used the 113-06201-080.hex firmware, 113-06201-080.eep eeprom data and 113-06202-020.hex bootloader files provided on the Jyetech homepage.

Testing if the chip is there:

Setting the correct fuses:

Writing the EEPROM data:

Writing the bootloader:

Writing the firmware:

I’ve had it crash again, but it seemed to take a bit longer than usual. The current draw is still only 190mA and not 240mA like the other DIY KIT. 240mA should be normal according to Jyetech. Maybe next weekend or so I’ll compare the two scopes and see if this one crashes more often than the other one. If it is still not “fixed”, I think I’ll leave it like it is right now. It don’t feel like poking in there much more or hunting for power supply / decoupling problems anymore. I think I said that when it crashed the cpu didn’t feed any clock to the ADC anymore (damn indirect speech). This time the ADC kept working when it showed strange behaviour, so maybe that’s an improvement ? I don’t know.

Now I’ve got a possibly still good ATmega64 sitting here and I need a project for it ;-)

>> http://groups.google.com/group/jye-tech-oscilloscopes <<

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2 Responses to Jyetech AVR digital oscilloscope DIY KIT — trying to fix it – part 2

  1. Alan Parekh says:

    Great video. I felt your frustration just watching the video, I felt like throwing something (I am surprised you didn’t)…

    What type of solder are you using? It seems to have a very long working time. I would have expected the chip to be affixed when it moved on you.

  2. robert says:

    For desoldering I used a low melt Bismuth alloy sold under the brand name ‘ChipQuik’. A small test set is very affordable and the alloy lasts quite a while, as you only need very little. The supplied flux runs out much faster. It stays liquid for several seconds because its thermal conductivity is very low. It keeps the heat. I’ve written a short review about it.

    Regarding the scope. It seems that the latest firmware runs pretty well on it. It may be an old revision board (also the front panel cut-out was too small for the LCD) and maybe tight timings in the code made it run unreliably. I don’t care anymore ;-)

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