CMU200 repair attempt - boot error, stuck on "stuc.cpp".

[Yansi]

Hello,

I am currently still not at home, where I have my lab and all stuff. I'll be back likely on friday.  Need to disassemble the module back again and desolder the 16.2 ohm resistor. Only then we can distinguish what the values of the two shunt resistors are. Will report back then as I've promised.

Y.

[YU7Q]

We look forward to your reply. 

[Ice-Tea]

Two pointers for backlight replacement:

- as far as I remember, there's only 5V on the BL connection and 12V is not readily available anywhere near. Most LED"inverters" I've seen are 9V+
- The CCFL itself can be found as well, but it's an L-shaped tube so no entirely straight forward either...

[Yansi]

I plan to design a custom switchmode constant current boost converter for the LED backlight, that would fit in the original place where the CFL inverter lived.

I've just arrived home, so tomorrow I'll start working on it.  Need to identify the original BL connector first.

[YU7C]

About RF4IN broken input attenuator:

I put only 18.2 Ohm serial resistor (no shunt resistors), and got T-attenuator, with a good accuracy (within 0.5dB) up to 200-300MHz, and about 2.0-2.5dB lower results on 1GHz.
Also measured RL is better than 30dB on freq. up to 500MHz, and about 25dB on 1GHz.

Still no information about shunt components.

Vojislav

 

[Yansi]

Ah, now I see I did not post my findings 

The two shunt components, or at least the one near the input, measures >20Mohm, after desoldering the 16.2ohm resistor.  Measuring across the other shunt component (with the rest of the instrument following it), measured 82 ohm, almost spot on.

I have absolutely no idea, what that high resistance component is. But it seems is not a resistor.

Same component used in different places, even near the P3 port.

If you look closely, it even does not look like a regular resistor.