CMU200 PSU erratic ON/OFF

[BeO]

Hello

I am new on this forum , I try to learn RF and built a Ground Radar as project

I have purchase in 2016 on Ebay UK , one CMU200 which have failed , power supply have failed , thanks to Ericmax on this forum for repair tips BUT after repair

my actual situation is :

my CMU 200 -02 : it's start normally and works fine regarding both spectrum and generator but it auto switch off when it wants by a similar way I press the one ON/OFF button ( shutdown in progress and now it s switch off at the bios screen level

I have all the power supply green LED OK 
I have change the TI SOIC 10 on the main board in case off but no change regarding the auto switch off
I have check the ON/OFF button , soft PCB is OK
I have check all connectors , nothing wrong
I have remove signal group cards ''option'' to eliminate possible ''short'' but the defect is still the same

Now ( 20 April ) after several power ON power OFF trials ;

PSU start OK
Green LEDs on base board are OK
BUT
I go straight from orange to green led on the front panel ( ON/OFF ) , and nothing start 

I am very disappointed by R&S multiples failures cases , and the fact that the maintenance manual is not available

BeO

[BeO]

Hello

I have succeed to locate a copy of the service manual , problem seems to be the lithium battery flat on the computer board , I will run a disassembly and battery identification to order a new , there is two battery model possible on in 3.6v and one in 3V

I will post the result soon

Thanks

BeO

[richnormand]

You might want to go through this thread about PSU issues.

Not the main theme but several replies do seem to address some of  your problems.
https://www.eevblog.com/forum/repair/rohde-schwartz-universal-radio-communication-tester-cmu200-psu-issues/

As far as the "service" manual all I have is pretty generic and not that useful as it only includes high level flowcharts.
Is yours including actual schematics?

I collected quite a bit of info on the CMU200 so let me know if you want to get in touch. Also in that thread, and another one I started on the RxTx module, you will find links to people that know a lot more about the CMU200 that I do.

PS: does BeO refer to beryllium oxide?

[BeO]

Hello

thanks for your feedback

my CMU have start to generate self ''automatic shutdown'' more and more quicker so the explanation regarding battery fail looks reasonable

I have switch PSU from my other CMU200 ( I enjoy problemss so that a ''250'' which works on my other CMU200/30 , nothing change same defect . green led OK , no start

I will try to track on/off button on the computer board

I agree regarding the service manual that not a detailed service manual , th ereal serice service manual with all schematics and circuits is the ''module service manual## I try to loacte one copy , but as this ''module service'' is a true internal doc from R&S that look difficult

This afternoon I try to change the battery and restart the CMU200/02 and will post regarding the result

BeO

[BeO]

Hello

Afternoon progress

I have change the Lithium battery for a new one ( CR2032 ) as the installed one was clearly dead

NO change

But when I have manipulated the CMU200 , the defect have changed as self restart trials. shutdown ....  , front panel keyboard shows to be very sensitive effect around On/Off and F1 touch

after to have disassembled the front panel the flexible PCB was corroded on one track between on/off and F1 touch

I have switch the flexible PCB by using the flexible PCB of my other CMU200 (30 ) and now the CMU200 works fine

Flexible PCB of the keyboard looks very sensitive to corrosion as the membrane is very thin and area arround on/off / F1 is stressed by numerous use

As conclusion now my CMU200 / 02 works gain

I now search to locate a spare flexible PCB in good shape to complete my CMu200/30 and solve boot problem

I have a signal unit available which was removed from another CMU200  if that can help someone

Best Regards

BeO

 

[RF_fanatic]

Just read your topic for first time. Indeed your behaviour sounded like a foil issue. It is a often occuring problem, most of the time manifested by a shut donw when pressing other buttons on the row on the bottom.

I have seen replacement units for the front foil, made by a chinese (?) guy. He copied the foil on a very thin PCB board including an added flexible part for the connector. That would be an option as foils are very hard to find!


But I can'n'r recall where I found it. I know it were CMU for sale for which he had made the above boards

[Qw3rtzuiop]

There are replacemant PCBs available on Taobao:
https://world.taobao.com/item/544961277461.htm?fromSite=main&spm=a230r.1.14.194.76bf523nb9jsk&ns=1&abbucket=17#detail
But i didnt order one yet.

[BeO]

Hello

Thanks for the link

I have order one from R&S the cost is 170 Euro

Regards

BeO