Rohde & Schwarz Universal Radio Communication Tester CMU200: PSU problem

[msraya]

I would put simple LL4148 

http://www.marsport.org.uk/smd/sod80.htm

Manuel

[Pieh0]

Just ordered "a few" of them, could only get 100 as a MOQ, so at least i'll have spares

[Pieh0]

Well it's fixed, for the moment.

Changed that transistor and the diodes, and it's started up!

Seems like what ever killed the PSU also killed the DSP module :/.

Thanks for the help

[richnormand]

Well it's fixed, for the moment.

Changed that transistor and the diodes, and it's started up!

Seems like what ever killed the PSU also killed the DSP module :/.

Thanks for the help

Well that is good news indeed. So you now have two CMUs.

[Pieh0]

Well that is good news indeed. So you now have two CMUs.

1 Working and 1 working apart from the DSP. Swapped the boards inside around and it's the main processing board that's died, so maybe it's a voltage reg or something, but trying to probe in there will be a pain.

Something to work on later .

Here's the board that died. http://imgur.com/a/V5HIP

[richnormand]

Well that is good news indeed. So you now have two CMUs.

1 Working and 1 working apart from the DSP. Swapped the boards inside around and it's the main processing board that's died, so maybe it's a voltage reg or something, but trying to probe in there will be a pain.

Something to work on later .

That could be a difficult one.
Anything on the board that looks like it would have taken the blunt of it, like a tantalum decoupling cap or voltage regulator or such?

[hafrse]

Hello Ericmax ,

Just curious, what is the type of the power supply in your CMU200, is it a SN230 or SN250.

Thanks

Good evening.

small post to confirm my troubleshooting CMU200.

Probleme: abrupt shutdown of CMU, as if a fuse had burned.

1: Troubleshooting PSU: 12V STB LED flash on backplane> replacing TOP200YN by TOP222YN. ( look on Mouser )

Testing the PSU removed CMU: B1 shunt to GND> PSU works well.
test the PSU in the CMU> 12V LED flash STB> problem on CPU board.
The 12V STB enters directly on a  LM2651MTC-ADJ regulator.

http://www.ti.com.cn/cn/lit/ds/symlink/lm2651.pdf

This regulator is short circuit.
2: Replacing LM2651MTC-ADJ (Mouser or Digikey)

Testing the CPU directly connected to the CMU ( Without LCD, PCMCIA and keyboard ) > CMU works well. ( motherboard post boot BIP)

reassembly of the front panel and replaced on the CMU.

everything is Ok my CMU working again. 

If it helps users CMU200 or CRTU, hoping to be useful.

[hafrse]

Hello,

I have a CMU200 with a bad power supply, the type is SN230 1091.2320.00 . I can get the SN250  1091.1982.00 type instead, are they compatible? the only thing I find on the SN250 type is that it has an extra orange socket with 4 pins near the main socket. Bothy are for the CMU200. According to the seller of the SN250 , the orange socket goes to a power cable to feed the signaling module which I don not have in my CMU200.

Many thanks in advance! 

[richnormand]

Hello,

I have a CMU200 with a bad power supply, the type is SN230 1091.2320.00 . I can get the SN250  1091.1982.00 type instead, are they compatible? the only thing I find on the SN250 type is that it has an extra orange socket with 4 pins near the main socket. Bothy are for the CMU200. According to the seller of the SN250 , the orange socket goes to a power cable to feed the signaling module which I don not have in my CMU200.

Many thanks in advance!

My CMU200 has the SN250. From what I could see inside the PSU the extra plug for the signalling module just connected to the regular outputs. My guess (could be wrong here) is they are the same supply apart from the extra plug and perhaps more current output for the extra module? If you do not get better feedback I could take my PSU off the unit and have a look for you, post some photos, if time is not an issue. Also the plug looked like a regular old style hard drive plug....

[hafrse]

Thanks to let me know/confirm that it only feeds the signaling module, I have pictures of the SN250 no need to take your power supply out. I will try the SN250 when I get it  and test it in my CMU200.
Many thanks!

Hello,

I have a CMU200 with a bad power supply, the type is SN230 1091.2320.00 . I can get the SN250  1091.1982.00 type instead, are they compatible? the only thing I find on the SN250 type is that it has an extra orange socket with 4 pins near the main socket. Bothy are for the CMU200. According to the seller of the SN250 , the orange socket goes to a power cable to feed the signaling module which I don not have in my CMU200.

Many thanks in advance!

My CMU200 has the SN250. From what I could see inside the PSU the extra plug for the signalling module just connected to the regular outputs. My guess (could be wrong here) is they are the same supply apart from the extra plug and perhaps more current output for the extra module? If you do not get better feedback I could take my PSU off the unit and have a look for you, post some photos, if time is not an issue. Also the plug looked like a regular old style hard drive plug....

[Brainbox]

If You do not intend to use the signalling unit, just pull them out and run the hardware change utility.
For normal RF measurements they are of no use and only pull a lot of unneeded power from Your supply.
Besides that the CMU becomes much quicker during startup.

[richnormand]

Hello,

I have a CMU200 with a bad power supply, the type is SN230 1091.2320.00 . I can get the SN250  1091.1982.00 type instead, are they compatible? the only thing I find on the SN250 type is that it has an extra orange socket with 4 pins near the main socket. Bothy are for the CMU200. According to the seller of the SN250 , the orange socket goes to a power cable to feed the signaling module which I don not have in my CMU200.

Many thanks in advance!

Looks like it only feeds that one module on the outside, as you suspected. And if I remember correctly inside the PSU it just tapped the regular output rails, nothing special. My guess is you should be OK.

[hafrse]

Hello,

I have a CMU200 with a bad power supply, the type is SN230 1091.2320.00 . I can get the SN250  1091.1982.00 type instead, are they compatible? the only thing I find on the SN250 type is that it has an extra orange socket with 4 pins near the main socket. Bothy are for the CMU200. According to the seller of the SN250 , the orange socket goes to a power cable to feed the signaling module which I don not have in my CMU200.

Many thanks in advance!

Looks like it only feeds that one module on the outside, as you suspected. And if I remember correctly inside the PSU it just tapped the regular output rails, nothing special. My guess is you should be OK.

Many thanks for the pictures!

[RF_fanatic]

I can confirm the SN250 will work as replacement for the SN230

[hafrse]

Hello,

Now I have a working power supply, to the next problem, the CMU starts and boots direectly when I press the main power on the back, the cmu200 boots ok but I can not shut it down from the front soft button to standby mode. No message when I press that says  the system is shutting down. I replaced the power supply with the one from my other working cmu, same problem , replaced the keyboard pcb, same problem.
Has anyone information about this start/standby soft botton "logic"  ? is it on the CPU board ? any keyboard chip involved ?
Thanks for any info

[Brainbox]

Did you mount the front panel firmly in place?
I had problems with the "on" button too.
It went out that the front panel was not exactly in place and the connectors from the front panel to the motherboard did not mate complete.
I did not fit the little screws which hold the front panel in place and that causes a mismatch.

[richnormand]

Hello,

Now I have a working power supply, to the next problem, the CMU starts and boots direectly when I press the main power on the back, the cmu200 boots ok but I can not shut it down from the front soft button to standby mode. No message when I press that says  the system is shutting down. I replaced the power supply with the one from my other working cmu, same problem , replaced the keyboard pcb, same problem.
Has anyone information about this start/standby soft botton "logic"  ? is it on the CPU board ? any keyboard chip involved ?
Thanks for any info

If the suggestion from Brainbox does not pan out for you I would suggest looking at pin B1 on the PSU plug. That is the "soft start/off" pin that should go from 12V to 0 when switching. It then goes via the motherboard to the front panel plug. Also pin A1 looks like the "power good" line.  You might want to check these signals.

Their locations and pinouts are shown in the first pages of this thread.

[eriklidgren]

Thank you all who contributed to this thread. It helped me troubleshoot my CMU200. At the beginning I suspected the power supply. It would start to power up and then die a few seconds into the boot sequence. This would loop continuously. I found that I could get it to boot successfully when I reinserted the keypad connector. But It would die  and restart when I pressed any button on the frontpanel. I ordered a replacement keypad and now it works. The old keypad silver plating looks tarnished.

[hafrse]

Hello,

Now I have a working power supply, to the next problem, the CMU starts and boots direectly when I press the main power on the back, the cmu200 boots ok but I can not shut it down from the front soft button to standby mode. No message when I press that says  the system is shutting down. I replaced the power supply with the one from my other working cmu, same problem , replaced the keyboard pcb, same problem.
Has anyone information about this start/standby soft botton "logic"  ? is it on the CPU board ? any keyboard chip involved ?
Thanks for any info

Hello,
Problem is solved now, it was the standby circuit which was not working (can be a controller chip, etc...) , I replaced the CPU board and now it works as it should.

[hafrse]

Hello,

Now I have a working power supply, to the next problem, the CMU starts and boots direectly when I press the main power on the back, the cmu200 boots ok but I can not shut it down from the front soft button to standby mode. No message when I press that says  the system is shutting down. I replaced the power supply with the one from my other working cmu, same problem , replaced the keyboard pcb, same problem.
Has anyone information about this start/standby soft botton "logic"  ? is it on the CPU board ? any keyboard chip involved ?
Thanks for any info

If the suggestion from Brainbox does not pan out for you I would suggest looking at pin B1 on the PSU plug. That is the "soft start/off" pin that should go from 12V to 0 when switching. It then goes via the motherboard to the front panel plug. Also pin A1 looks like the "power good" line.  You might want to check these signals.

Their locations and pinouts are shown in the first pages of this thread.

Thanks for the information, the pin is always logically 0 . when I press standby, no message on the display  appears saying that the system is shutting down, I suspected the standby circuit (controller chip, etc...), replaced the CPU card and now it works fine.
Thanks again

[EB5AGV]

Hi all,

As I have commented on a sepparate thread, I am also working on a faulty PSU. Mine is a PULS SN250

I have a doubt regarding a couple wires coming from the main PCB to the upper one. Wires are GREEN and BLACK in colour and come from a transformer. I think they should go to the BL and SW connections respectively on the upper board, as I guess the GREEN one could be close to BLUE (BLAU in GERMAN) and the BLACK one in German is SCHWARZ, so the SW. But of course this is just a guess. I take pictures of everyting but didn't picture that one 

Please, could you help me?

Thanks!

Jose

PS: I have used a previous picture of this thread to show what I mean

[hafrse]

Hello,

You are correct, the Black goes to SW.
My power supply died yesterday when I was uninstalling/ installing the CPU card..., no standby voltage and TOP222 is ok.
it seems that these power supplies are very sensitive.
What is wrong with yours?
George

[EB5AGV]

OK, thanks!

Well, mine did not generate 5.2V and 3.3V. So, following a previous post on this thread, I analyzed the small plug-in board. And, yes, exactly the same transistor was bad!. In my unit there were some corrosion signs on it. I will post some pictures.

I replaced it and powered it out of the unit, and yes, the PSU came back to life.

But, this morning, I have assembled it and put it back into the CMU200. And then, just switching the PSU switch, something has exploded inside!

I have looked and it is very uncommon: the dual hole ferrite just close to the main bridge, on the red and black cables, was cracked in two and there were signs of an spark among the positive and negative cables, just below the ferrite. I guess it was due to my cleaning work which perhaps had left some residue just below the ferrite. But, anyway, it was quite uncommon and has scared me 

Both fuses were also gone. So I have put new ones but, as I was unsure of the cabling, I had not yet powered it, just in case.

So, after lunch, I will try it again. Let's close fingers! 

Jose

[EB5AGV]

Well, I have good and not so good news.

The good ones is that the PSU is working fine. So I have been able to boot the unit for first time 

And then the fun stops... It takes a lot of time on the startup window, showing on Process BaseDiscoverOptionsBegin 

After several minutes, it continues, shows all the installed options and even the serial number. Once, it has shown a "non-volatile RAM empty error" after that, but the next time it has not.

Then you can continue, but no function really works and, when trying to do something (as activate the spectrum analyzer), all of them end with a red framed System Errror window.

Installed software is V 4.51. I have tried to change to V 4.53 (as it is already on the hard disk), but it kept doing the same, so I have reverted back to 4.51

UPDATE: after the N-th  attempt, after the red error window and a power down sequence, now it does not boot up!. When you connect the power supply, the GREEN light on the front panel lights immediately after just a blink of the YELLOW one. And that is all!. No fan running, nothing. I have waited for some time, with the PSU disconnected but, so far, it keeps doing the same. The only LED that shines is the 12V Standby (besides the front panel green one!)

Any idea?

Thanks!

Jose

[EB5AGV]

Well, I would say that these PSUs are crap 

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