CMU200 repair help - Page 1
Forum section: electronics / rf-microwave

author: cherrylee
author_rank: Contributor
timestamp: December 09, 2020, 09:18:36 am
content: I have a CMU200, but it is a malfunctioning machine,After the boot is complete, the prompt:FM calibrationWhen i execute the "System Selftest"，all passed.But when i execute the "Internal RF Loop Path 1",the error is:"Fct. System Error""No DDC Driver"Has anyone encountered such a problem and can give some suggestions how to fix it. thx..

author: Bicurico
author_rank: Super Contributor
timestamp: December 09, 2020, 09:32:51 am
content: The last picture with error is IMHO the worst:It means, if I remember correctly, that the DSP module on the Digital Board is broken. Why? Nobody knows. When that happens, you can only hope for a replacement part.The Digital Board of a CRTU has two DSP modules (I guess one for each RXTX board) and can operate in DOS mode with just one inserted, so it can act as a donor for the broken Digital Board of the CMU200. If you buy a broken CRTU with working Digital Board, you get two DSP modules that you can use to revive two CMU200!I have, myself, two broken DSP modules and would love to get two working ones...Note: some options (WDCMA, I think) are stored in these DSP modules. If you had this option and replace it with a DSP that does not have this option, it is gone. The keygen will not be able to activate these lost options.Good luck!

author: Bicurico
author_rank: Super Contributor
timestamp: December 09, 2020, 10:04:26 am
content: Looking at it again, I think I am wrong and the problem is not related to the DSP module of the Digital Board...

author: Qw3rtzuiop
author_rank: Frequent Contributor
timestamp: December 09, 2020, 10:09:42 am
content: Have you tried updating the firmware?https://xdevs.com/doc/R&S/CMU200/device%20software/And after that execute "Firmware update after board change" from the boot menu.

author: cherrylee
author_rank: Contributor
timestamp: December 09, 2020, 10:26:41 am
content: I can be sure that the problem is the digital board；Because I can perform RF LOOP by replacing someone else’s digital board.I also execute "Firmware update after board change". the error is same

author: Bicurico
author_rank: Super Contributor
timestamp: December 09, 2020, 10:42:32 am
content: If the problem is the Digital Board, then for sure it is the DSP module.The problem is that the DSP module is essentially a FPGA and not much else to break.

author: cherrylee
author_rank: Contributor
timestamp: December 10, 2020, 05:12:22 am
content: I took apart the digital board and found that my digital board lacked three small boards, I think the problem lies here.Does anyone have a picture of the disassembled digital board, can you share it?

author: cherrylee
author_rank: Contributor
timestamp: December 10, 2020, 07:59:02 am
content: Who has the schematic？Can anyone share a schematic？ thx..

author: Bicurico
author_rank: Super Contributor
timestamp: December 10, 2020, 09:49:16 am
content: Take a look here:https://www.eevblog.com/forum/repair/cmu200-rohde-schwarz-hangs-during-basediscoveroptionsbegin/And here:https://www.eevblog.com/forum/repair/cmu200-how-to-do-reflow-ic-on-dsp-board/--> No repliesAnd here:https://www.eevblog.com/forum/buysellwanted/wtb-cmu200-digital-board-or-dsp-module-from-digital-board/--> No repliesGood luck!Regards,Vitor

author: Mark19960
author_rank: Regular Contributor
timestamp: December 10, 2020, 10:21:02 am
content: I have some photos but the forum won't let me upload them."Your attachment has failed security checks and cannot be uploaded. Please consult the forum administrator."Beats me.Here is probably the most important one to you if you wanted to see the daughterboards.It's from one of my junkers.

author: Bicurico
author_rank: Super Contributor
timestamp: December 10, 2020, 10:40:06 am
content: Just an additional note:The CMU200 handles only one RXTX card, while the CRTU handles two RXTX cards.The DIGI BOARD has space to fit one or two sets of modules (DSP module and another module, not sure what it does or what it is called).This is why there are apparently missing modules - they are not missing.Regards,Vitor

author: cherrylee
author_rank: Contributor
timestamp: December 11, 2020, 06:14:54 am
content: thank you all，I found the problem, the digital board is missing three small boards.My friend re-sent me three small boards, and I’ll give back in a few days.-------------------------And my system version is:3.8I update it to 5.21,when i execute :"System Selftest",the error is notice dsp board.-------------------------

author: cherrylee
author_rank: Contributor
timestamp: December 24, 2020, 01:45:37 am
content: I completed the small board installation of the digital board.The machine is running normally and all tests can pass.thxNow I am trying to install the option of CMU-B83.However, when I plugged in the B83 option and re-updated the system, an error appeared.When I unplug the B83 option, the error disappeared.Has anyone encountered this kind of problem？