Author Topic: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem  (Read 45124 times)

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Offline richnormandTopic starter

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #100 on: October 13, 2016, 09:11:19 pm »

What happens now is that the PSU does not start up!. It has the right voltage on the POWER ON pin (B1), but when the unit sets it low or when you do it with a resistor, the PSU does not start.


Jose

Ok probably means the first cap from the line  and the first stepdown converter should work.
To make sure measure the 350V and 280V  for the following stepdown trans.across these to make sure. Just to make sure you still have a full bridge, not one with two open diodes. The fact that both fuses were gone, ouch!

Then since the original TOP222 seems to be fragile, measure the 12V standby output at the output connector, in addition to the 5V soft on/off.

If OK, short circuit the soft on/off and see if any output voltage rail has a short "blip" and then shutdowns. See previous posts in this thread. If it does, the little board has to be looked at again.
Each of the main supply rails have their own rectifier, regulator, over current and voltage. If any of those has an over current or short it will cause a shutdown and the transformer with all the taps.

PSU works fine out of the unit without a load (not always true for this type of PSU). First order of the day then is to get the PSU going. But you need to figure out if there are issues with modules on the motherboard that could have caused this also.

Other comment: RAM, I also got a similar messages and inconsistent boots on my unit. Changed the coin cell on the front board and ran the tool utility on bootup to refresh the configuration.

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Offline EB5AGV

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #101 on: October 13, 2016, 09:32:06 pm »

What happens now is that the PSU does not start up!. It has the right voltage on the POWER ON pin (B1), but when the unit sets it low or when you do it with a resistor, the PSU does not start.


Jose

Ok probably means the first cap from the line  and the first stepdown converter should work.
To make sure measure the 350V and 280V  for the following stepdown trans.across these to make sure. Just to make sure you still have a full bridge, not one with two open diodes. The fact that both fuses were gone, ouch!

Then since the original TOP222 seems to be fragile, measure the 12V standby output at the output connector, in addition to the 5V soft on/off.

If OK, short circuit the soft on/off and see if any output voltage rail has a short "blip" and then shutdowns. See previous posts in this thread. If it does, the little board has to be looked at again.
Each of the main supply rails have their own rectifier, regulator, over current and voltage. If any of those has an over current or short it will cause a shutdown and the transformer with all the taps.

PSU works fine out of the unit without a load (not always true for this type of PSU). First order of the day then is to get the PSU going. But you need to figure out if there are issues with modules on the motherboard that could have caused this also.

Other comment: RAM, I also got a similar messages and inconsistent boots on my unit. Changed the coin cell on the front board and ran the tool utility on bootup to refresh the configuration.

Yes, maybe the bridge has been damaged. I will replace it, as it has suffered a big overload. Thanks for the hint!

Regarding the battery replacement, it is what I have done before, thinking that the non-power issue could be related with the CPU. The battery measured only 2.4V. I have replaced it and will reset configuration as soon as I get the PSU back to work!

I will let you know what I find.

Thanks!

Jose
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Offline EB5AGV

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #102 on: October 13, 2016, 10:51:33 pm »

What happens now is that the PSU does not start up!. It has the right voltage on the POWER ON pin (B1), but when the unit sets it low or when you do it with a resistor, the PSU does not start.


Jose

Ok probably means the first cap from the line  and the first stepdown converter should work.
To make sure measure the 350V and 280V  for the following stepdown trans.across these to make sure. Just to make sure you still have a full bridge, not one with two open diodes. The fact that both fuses were gone, ouch!

Then since the original TOP222 seems to be fragile, measure the 12V standby output at the output connector, in addition to the 5V soft on/off.

If OK, short circuit the soft on/off and see if any output voltage rail has a short "blip" and then shutdowns. See previous posts in this thread. If it does, the little board has to be looked at again.
Each of the main supply rails have their own rectifier, regulator, over current and voltage. If any of those has an over current or short it will cause a shutdown and the transformer with all the taps.

PSU works fine out of the unit without a load (not always true for this type of PSU). First order of the day then is to get the PSU going. But you need to figure out if there are issues with modules on the motherboard that could have caused this also.

Other comment: RAM, I also got a similar messages and inconsistent boots on my unit. Changed the coin cell on the front board and ran the tool utility on bootup to refresh the configuration.

Yes, maybe the bridge has been damaged. I will replace it, as it has suffered a big overload. Thanks for the hint!

Regarding the battery replacement, it is what I have done before, thinking that the non-power issue could be related with the CPU. The battery measured only 2.4V. I have replaced it and will reset configuration as soon as I get the PSU back to work!

I will let you know what I find.

Thanks!

Jose

Some more information... The bridge is OK. I get about 270V on the RED and BLUE wires, just after the bridge and then close to 400V on C215 (220uF/400V cap) on the top PCB.

The 12V STANDBY is present and stable. The POWER ON line is as shown on the document, close to 11V on STANDBY. But when I put it to GND, nothing happens. There is no glitch on any output. It is as if the unit did not notice the ON signal. I have checked and it goes to the vertical PCB among top and bottom ones. There are some ICs there and the first one is a CD4093BCM  NAND,Schmitt Trigger. The bad thing is that it is located on the inner side, so checking how it operates is not easy.

Regards,

Jose
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Offline hafrse

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #103 on: October 14, 2016, 08:53:52 pm »
Well, I would say that these PSUs are crap  |O

What happens now is that the PSU does not start up!. It has the right voltage on the POWER ON pin (B1), but when the unit sets it low or when you do it with a resistor, the PSU does not start.

So it has lasted for about one hour!

I am about to open it again...

Regards,

Jose

I agree, I have now 2  dead power supplies, no 12v standbuy output. One of them was working before 3 days ago, it just stopped after I reinstalled the front frame, something is killing them and they do not tolerate any thing...
Will check the TOP200, I have ordered 5 of them.
   Regards,
George
 

Offline richnormandTopic starter

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #104 on: October 15, 2016, 01:38:04 am »



 I have checked and it goes to the vertical PCB among top and bottom ones. There are some ICs there and the first one is a CD4093BCM  NAND,Schmitt Trigger. The bad thing is that it is located on the inner side, so checking how it operates is not easy.

Regards,

Jose

Ya, I found the same problem for testing mine. I ended up soldering several wirewrap wires to about five or six points I wanted to check and labeling them. Then I reassembled the whole PSU and did the measurements. You might notice it took me quite a while to find the open resistors and diode (front end of this thread). I don't really know of another method to do this, unless someone comes up with a better suggestion :)

By the way my symptoms did look pretty much like yours too.

One of the most complicated PSU I ever dealt with. As Scotty would say " The more complicated the plumbing the easier it is to clog the system"....
« Last Edit: October 15, 2016, 01:40:25 am by richnormand »
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Offline EB5AGV

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #105 on: November 15, 2016, 08:36:59 pm »
Well, I have managed to get the CMU200 running again. I got a faulty PSU and have fixed it  :-+

But then the problem it had before remains. I have already replaced the CMOS battery and run the BIOS CMU Default configuration. But, on powering up, the unit hangs on BaseDiscoverOptionsBegin Process, showing on Info window just SW: V 4.51, with Model and Serial# blank. And in Options there is nothing shown for some long time.

After about 5-10 minutes, the Options windows is filled with the unit configuration and the boot up continues. But then, if you select for example RF Spectrum, when you press ON, there is s System Error (Filename: R nl-page in u-mode, Line 615) and tells you to power cycle the unit.

Any idea of what could be happening?

Thanks!

Jose
« Last Edit: November 15, 2016, 09:46:26 pm by EB5AGV »
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Offline richnormandTopic starter

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #106 on: November 15, 2016, 08:50:30 pm »
1)
What was the root cause of the failure with your PSU EB5AGV ?

2)
My first reaction would be to recheck all the connectors from the motherboard and the front computer and the HDD. Then suspect corrupted data transfer from the old HDD.
check that the small fan in the front module is running (mine was not, seized)
3) make a full bit copy image of the hard drive (procedure mentioned on this forum before, using HDD-Raw-Copy tool by user _Wim_) These hdd are getting old and near failure.
4) Once you are sure your disk image is OK, go to DOS (attach usb keyboard and Alt-F4) and chkdisk and defrag the HDD.

This would give you a backup to change disk drive if needed. I used a compact flash (bootable type) with a converter to mimic the HDD and transferred the disk image to it. Mine used to lock up randomly during boot up and it stopped doing it since I am not using the original HDD. I suspect some corrupted software data until the drive warmed up as I also had issues reading it with my HDD to USB converter while setting up for the transfer.

Even if that does not solve your issue at least you will have a proper backup of the OS.

Good luck with it.


« Last Edit: November 15, 2016, 09:02:53 pm by richnormand »
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Offline RF_fanatic

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #107 on: November 15, 2016, 10:19:27 pm »
This problem is most likely caused by a dead DIG unit. I've seen it with multiple units.

The dead DIG unit gives the typical very  long  waiting  time without showing serial  number.
« Last Edit: November 15, 2016, 10:23:34 pm by RF_fanatic »
 

Offline EB5AGV

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #108 on: November 15, 2016, 10:51:38 pm »
This problem is most likely caused by a dead DIG unit. I've seen it with multiple units.

The dead DIG unit gives the typical very  long  waiting  time without showing serial  number.

When you say dead, you mean not fixable?

Jose
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Offline RF_fanatic

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #109 on: November 16, 2016, 01:43:32 pm »
It might be fixable but inside the dig module there are multiple boards.



I have some defective dig boards myself and also working dig boards so minimizing the problem to board level would be the next step for me.

But i have limited time..

But perhaps it would help others to pick it up after i identified it on board  level. In that case i can give it higher priority. (At the moment im focussing on calibration of deviations of the cmu)

 

Offline EB5AGV

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #110 on: November 16, 2016, 03:27:27 pm »
It might be fixable but inside the dig module there are multiple boards.

I have some defective dig boards myself and also working dig boards so minimizing the problem to board level would be the next step for me.

But i have limited time..

But perhaps it would help others to pick it up after i identified it on board  level. In that case i can give it higher priority. (At the moment im focussing on calibration of deviations of the cmu)

Yesterday I opened the DIGITAL BOARD module... Yes, it had four plug-in boards, two larger and two smaller, and there was plenty of dark dust and some signs of slight corrosion. But even after a careful cleaning, the unit does the same.

It would be great to have known-good boards to swap. I offer myself to work on this if I can get an spare DIG board.

Regards,

Jose
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Offline RF_fanatic

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #111 on: November 16, 2016, 10:16:34 pm »
I will try if I can trace back the fault to internal plug-in module level of the DIG board tomorrow evening or otherwise this weekend.

I have a special CMU setup in which I can easily do checks on module level for a quick assesment of faulty units. Uptill now I've used it on module level but can be easily be altered for plugin level.

It would be wise to open a separate topic for this.
« Last Edit: November 16, 2016, 10:18:45 pm by RF_fanatic »
 

Offline richnormandTopic starter

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #112 on: November 16, 2016, 10:39:33 pm »
I will try if I can trace back the fault to internal plug-in module level of the DIG board tomorrow evening or otherwise this weekend.

I have a special CMU setup in which I can easily do checks on module level for a quick assesment of faulty units. Uptill now I've used it on module level but can be easily be altered for plugin level.

It would be wise to open a separate topic for this.

If you do open a new topic please leave a note here too, so the rest of us with dodgy CMUs can follow it.  BTW thanks for all your efforts on these topics RF_fanatic, much appreciated.
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Offline msraya

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #114 on: October 25, 2018, 08:01:15 am »
Hello!!

Same problem here with LM2651MTC-ADJ regulator.  Only I put a LM2651MTC-3.3 and burned something else  |O
I will try to put another LM2651 to see if it works, but I think i burned something..

Someone with a spare main board FRM6 to exchange??

Manuel
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Offline RF_fanatic

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #115 on: October 26, 2018, 08:49:16 pm »
I do have a couple of FMR5 units if that would help. Only problem is that the display iterface is totally different..
 

Offline wiredwrx

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #116 on: March 30, 2020, 01:06:48 am »
Sorry to resurrect an old thread, but just obtained a non-working CMU200, and all my searching revealed this thread as really the only resource for a resolution.  So, here goes:

Pulled off the cover, and noticed that the standby led was lit constantly, which I guess is good.  However, the power button on the front of the unit doesn't light up at all.  I removed the PSU, but can't seem to get any voltage out of the PSU on the bench...not even the standby voltage, which surprises me.

Put the PSU back in the unit, LED shows standby voltage, and grounded pin B1 through 200K resistor, but nothing happened.  None of the LEDs lit, and the unit is just dead.  Monitored B1 with a scope, and there is no voltage present with the PSU installed and powered on, and of course, no ground/low signal when the front panel button is pressed.

I tried to initiate turn on by grounding B1 through the 200K resistor with the PSU removed, and no go.

Really confused by all this, and my electronics knowledge just isn't great enough to figure this out alone.

Any direction or help would be greatly appreciated.

UPDATE:  So, with the PSU installed and connected, I grounded, without a resister, B1, and lo and behold, the PSU started, all the LEDs went green, and got some beeps, and the HD was definitely spinning and doing its thing, but no lights came up on the front panel, and the LCD stayed dark.  Gonna pull all the option slices out, and see if I can get it to boot, but at this point, I am leaning towards something wrong on the front panel or motherboard.  "Hopefully" I'll find something that burnt, or a misaligned or damaged cable, or something. 

UPDATE 2:  Got some beeps out of the unit, and with a flashlight, I am able to see something on the screen.  So, perhaps the invertor is not operating.  But still, no lights on the front panel, so still hoping/thinking there might be an easy solution once I get the front assembly off.

Kindly,
Michael
« Last Edit: March 30, 2020, 03:57:11 am by wiredwrx »
 

Offline richnormandTopic starter

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #117 on: March 30, 2020, 03:37:47 am »
I used much less than 800 ohms on B1 to start it if I remember correctly. You also should get the standby power even when the PSU is alone.
Unlike some PSU this one is fully functional when no load is applied. So there is no need to have it connected to the motherboard until all the proper voltages are present when it gets the "power good" signal.

You might want to read the whole thread at this point.

The initial posts in this thread will give you several things to check and include several pinouts.

In mine it ended up being a row of resistors that were defective (all open) in the current monitoring loop, but along the thread you will find other issues that people have identified and things to check.

I'll monitor this thread to follow your progress and see if I can help if you post more details.

Best of luck with it.
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Offline wiredwrx

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #118 on: March 30, 2020, 04:19:37 am »
Thanks for the reply.  I have been through the thread several times, though nothing has been exactly like what I am experiencing.

Also, don't forget that you also changed a diode along with those other resistors ;)

Gonna trace the front power button LEDs and the power button, and see what happens.

As an aside, I replugged in all the cards, and booted the unit by grounding B1.  It booted up properly, and then the led on RF3 lit showing input.  And, with a flashlight, it looks like the unit is at the SA screen, its hard to tell, but it definitely appears to be booting properly. 

Next step is to get the front off, and look for obvious damage, and see what I can find.

UPDATE:  Attached an Monitor to the VGA out, and kinda as expected, got a good signal, and was able to watch the unit post and boot.  But, none of the front panel buttons appear to do anything.  Leads me to believe that there is some sort of major issue with the front panel.  Time to delve in and see what I find.  ***Does anyone by chance have a pin out of the various connectors between the front panel and the other boards?***

Thanks
Michael
« Last Edit: March 30, 2020, 06:02:03 pm by wiredwrx »
 

Offline richnormandTopic starter

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #119 on: March 30, 2020, 07:59:00 pm »
My unit also had a dead display but seemed to try to boot. I could see some action with a flashlight.
Here is a link to the inverter board and how I removed the front panel:

https://www.eevblog.com/forum/repair/rs-crtu-need-help-removing-the-front-panel/msg1127200/#msg1127200

Turned out to be a bad smd fuse.

While you are there you should consider replacing the battery and checking the small cooling fan (mine was seized and the temperature monitors were indicating past high temps)

Another thing I did while in there was to bit copy and replace the hard drive. I kept the original as a backup copy and replaced it with a flashcard memory.

But first you have to find out why the command to the PSU is not getting there. There are several connectors between the front unit and the motherboard to check for proper connections.
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Offline wiredwrx

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #120 on: March 30, 2020, 08:28:27 pm »
Well, the plot thickens, or perhaps, I have figured it out.  Got everything apart, and started focusing on the green membrane behind the keys.  The membrane connects with a thin flat cable to J3 on the FMR5 board behind the display.  The flat cable definitely (well, to me, maybe no one else, please let me know) seems to have shorted and/or taken some sort of voltage/amperage it was not meant to. 

See the streaking/?burning? running up the cable in pic 1?

Also, it looks like something "delaminated" from the cable in pic 2-4?  Interestingly, I wonder if that was a fuse of some sort.  When flattened, there is a metal film of sorts on the "top" that shows continuity to ground.  Any one remember seeing something like that on their green membrane before?

Finally, I am hoping that nothing else took a hit.  A quick look around doesn't show any burnt parts, and the board looks pristine.  I am hoping that nothing blew, or, that these little chips in pic 5 are fuses, but will need a tweezer probe to check.  I can't see any markings with my aging eyes.

Thoughts?

P.S.  And, the fuse on the back light inverter blew, so have to deal with that.  I really hope they are related, because if not, then I may have more issues than I think.

Thanks,
Michael
« Last Edit: March 30, 2020, 08:30:36 pm by wiredwrx »
 

Offline wiredwrx

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #121 on: March 30, 2020, 08:33:21 pm »
While you are there you should consider replacing the battery and checking the small cooling fan (mine was seized and the temperature monitors were indicating past high temps)

Another thing I did while in there was to bit copy and replace the hard drive. I kept the original as a backup copy and replaced it with a flashcard memory.

But first you have to find out why the command to the PSU is not getting there. There are several connectors between the front unit and the motherboard to check for proper connections.

Thanks for the advice and direction.  I did just backup the HD, and will likely be putting in an SSD, if I can get it to work properly first.  I will also change the backup battery, and check the fan while I am at it, but mine doesn't appear to have a temp sticker.

Thanks,
Michael
 

Offline Qw3rtzuiop

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #122 on: March 31, 2020, 11:29:44 am »
I recommend an IDE to CF adapter. An ssd is overkill for the task and the OS wont use TRIM etc.
This adapter is in use for 1 year in my CMU200:
https://www.aliexpress.com/item/32575994548.html?spm=a2g0s.9042311.0.0.27424c4doOdtrA

My unit suffered from a broken keyboard foil to. There was similar damage on that flatflex cable.
You can buy cloned keyboard foils on Taobao for appr. 40$.
But i dont see burnmarks on your pics. It looks like corosion of the silver plating.

Edit:
This is the taobao link for the keyboard pcbs:
https://item.taobao.com/item.htm?id=544961277461

By this time they are also available on ebay but much more expensive.
« Last Edit: April 02, 2020, 07:59:25 am by Qw3rtzuiop »
 
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Online Ice-Tea

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #123 on: March 31, 2020, 11:53:48 am »
* The keypad membrane often looks black. Just the silver oxidizing, afaik
* They can often be repaired. Main cause of trouble is the delamination. If you look closely, you'll see a piece of tape connects the two layers. You'll need to replace that with copper tape or something. Don't try to solder it, doest work.
* If not: I can probably dig up a spare.
* Backlight: the inverters are prone to failure. You can find replacements but they are expensive. Easiest is just to get a LED replacement strip. Watch out: afaik, it runs of 5V, many of the LED inverter boards out there need 9V at least.
 
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Offline wiredwrx

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Re: Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem
« Reply #124 on: March 31, 2020, 05:28:50 pm »
* The keypad membrane often looks black. Just the silver oxidizing, afaik
* They can often be repaired. Main cause of trouble is the delamination. If you look closely, you'll see a piece of tape connects the two layers. You'll need to replace that with copper tape or something. Don't try to solder it, doest work.
* If not: I can probably dig up a spare.
* Backlight: the inverters are prone to failure. You can find replacements but they are expensive. Easiest is just to get a LED replacement strip. Watch out: afaik, it runs of 5V, many of the LED inverter boards out there need 9V at least.

Thanks for your responses.  ICE, if you have a spare membrane, that would be awesome.  I'll try and PM you.

I haven't decided about going LED or just repair the inverter just yet.  I assume the stock back light can be adjusted, and I may want to stick with that. 

Qw3rtzuiop, I was also thinking about using a CF adapter, and will likely do that instead of an SSD.  Thanks for confirming it will work, and for the link.

Thanks,
Michael
 


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