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New bench scope - Fnirsi 1014D, 7", 1GSa/s

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donwulff:
That's quite unfortunate, all of the power regulators and DAC amp https://github.com/pecostm32/FNIRSI-1013D-1014D-Hack/blob/main/Schematics/1014D/Scope_1014D_Power_Supply.png are connected straight to the 5V bus with no obvious over-voltage protection, as they do warn to use only the 5V supply that comes with it. And the MOSFET switch & diode are rated for 12V+ plus, so there's a good chance of frying a number of the power regulators, at the very least.

I wonder which relay that would be, however, best bet is probably to connect 5V and start measuring which of the regulators are working, though there seem to be other components on harm's way on the LCD path as well. I'm not going to check all of their data-sheets, but some of them could tolerate 12V input at least for a while, but at least the LCD DC-DC converters are strictly 5V input. There's no easy test points and I can't immediately identify the location of all the regulators, and if several components are fried, or shorted, it could quickly get more expensive to repair than get a new one, even if you're good with soldering iron.

Postal2:

--- Quote from: donwulff on June 06, 2023, 04:47:32 pm ---I can't spot the ferrite beads though, do they just go around the incoming USB power leads?

--- End quote ---
Marked on photo.

It's impossible to use it without those improvements. Absolutely not. May be if you school boy.

gargamel777:

--- Quote from: donwulff on June 18, 2023, 07:05:25 pm ---That's quite unfortunate, all of the power regulators and DAC amp https://github.com/pecostm32/FNIRSI-1013D-1014D-Hack/blob/main/Schematics/1014D/Scope_1014D_Power_Supply.png are connected straight to the 5V bus with no obvious over-voltage protection, as they do warn to use only the 5V supply that comes with it. And the MOSFET switch & diode are rated for 12V+ plus, so there's a good chance of frying a number of the power regulators, at the very least.

I wonder which relay that would be, however, best bet is probably to connect 5V and start measuring which of the regulators are working, though there seem to be other components on harm's way on the LCD path as well. I'm not going to check all of their data-sheets, but some of them could tolerate 12V input at least for a while, but at least the LCD DC-DC converters are strictly 5V input. There's no easy test points and I can't immediately identify the location of all the regulators, and if several components are fried, or shorted, it could quickly get more expensive to repair than get a new one, even if you're good with soldering iron.

--- End quote ---

Thank you,

It was just the boost driver for the backlight. Wish I knew there was a schematics available online for this scope. But good lesson learning & fixing  without it.

(I'm 1980s electronics guy who moved  soon in 1990s to IT, but somehow ended up fixing marine electrical/electronics  stuff on liveaboards in Indonesia these years :-)

Thanks again. I love this forum.

zenon:
This oscilloscope has an incredibly poorly designed input attenuator!
For different input sensitivity, the values ​​of different frequencies are totally different!
Has anyone dealt with this problem?
Otherwise, for fun, I made a voltage limiter to possibly protect the device from blowing up if the supply voltage rises. Voltage threshold is somewhere around 5.3V and depends on the zener diode.

zenon:
Hello!
I was able to adjust the attenuator on this unit to some extent.
Trimmer capacitors are 10-30pF, but it is good to use ones with a smaller value (5-20 or something similar).

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