CMU 200 frequency band gap - board 1100.2500.02

[piotrekjan]

Hi,

I discovered in my CMU band gap in freq. range ~1.2G - to ~2.2G. In general I've found post by RF_fanatic:
https://www.eevblog.com/forum/repair/rohde-and-schwartz-cmu200-rxtx-module-issues/50/
Indicating that board 1100.2500.02 causes failure.
In general I've removed this board from equipment - there is not to much on it, the ICs are 4 x AD829J, 4 x NE5534, 2 x AD835A, 1 x AT24C164. Additionally 2 diodes and pnp transistor. The rest is passive - resistors, capacitors, chockes.

Has anyone trying to repair this board ? In general its interesting, as these components do not seems to be used in some high freq. range - but maybe.
Sometimes internal bonding in ICs can fail after some temp./vib. rapid changes...
Of course I can check part by part but desoldering - soldering to test board - desoldering again and soldering again does not look optimal. So first check here in forum...

BTW. Has someone EEPROM content for it (I mean this 24C164 located on it) - that is my 1st suspected.

Regards,

[piotrekjan]

I've started playing a bit more with that.

Maybe the schematic, I've created to CMU200 RXTX board will help someone. I will try go path by path to recognize where 1.2G - 2.2 G is.
In terms of AUC_board # 1100.2500.02 I've checked EEPROM, it is ok.  I do not exclude from suspected yet. But now focus on RX path.

To those, who know -
Please share what SMD components are:
ANs67
LDP66
LDP73
N43

Update: I attach the LED states for different freq. bands. If LED is off means this path is not used for this freq.

[piotrekjan]

Not too much progress yet, but I've done measurement to recognize what switches are on when.
In enclosed pdf path for RFIN=1240MHz (so already in the band gap). All RF amplifiers seems to work correctly - valid DC voltage - what means are polarized correctly.