Products > Thermal Imaging

(new pic posted, please help) Cairns Viper, self-heating, some other questions

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Fraser:
Thread detailing reverse engineering of PCB’s, including comments from me on the topic.

https://www.eevblog.com/forum/eda/pcb-reverse-engineering/

Fraser

Bill W:

--- Quote from: Logan on October 04, 2021, 05:06:12 pm ---Maybe the controlling system is indeed on the sensor board, and the 6.1v pins is just power.

--- End quote ---

The 6.1V is some power rail (maybe 7V ?) less the saturation of the H bridge driver transistors and maybe a series resistor for current measurement.

Looking closely at the image where Fraser noted them, seems a bit suspect that the bottom two are legible and the top two might look a bit cooked ?
Not necessarily a cause, likely still just an effect.  Scope or DMM all pins on that op amp.

Bill W:

--- Quote from: Logan on October 04, 2021, 04:53:34 pm ---
--- Quote from: Bill W on October 04, 2021, 04:49:33 pm ---It did however nearly double the sensitivity !

--- End quote ---
Seriously? How?
Okay I'm doing it now.

--- End quote ---

It did indeed, we never knew why but that Ulis 03191 A-Si was known as 'Christine's magic sensor', must see if it ended up in the 'scrap'  :-X ;).  It was too weird to calibrate normally.
It was run for a good hour or two and was down to a short on the temperature feedback voltage making the sensor seem 'too cold'. 

The heat may have cooked the pixels or die amplifiers or perhaps done a bit of extra gettering.  But it was a stand-out image.

Bill

Logan:

--- Quote from: Fraser on October 04, 2021, 06:26:40 pm ---In this situation I would definitely begin reverse engineering of the TEC controller circuit to establish the location of key components and suitable test points.

--- End quote ---
Thank you. But I have never done such thing before, I will try to do it later and report back.

Logan:

--- Quote from: Bill W on October 04, 2021, 09:54:26 pm ---Scope or DMM all pins on that op amp.

--- End quote ---
I don't have a scope... How should I DMM the pins? I guess test the resistance to GND when power off, and voltage to GND when power on?

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