Rohde Schwarz ZVR VNA repair

[s0r0s]

Hi folks!

Recently I got this wonderful piece of equipment for a reasonable price. A miracle didn't happen and unit appeared to be faulty (sold "AS IS").
After boot up VNA shows "LO1-VCO faulty" error. S11(S22) magnitude chart shows just random data, while S12(S21) return almost flat line at 0dbm.
Then I decided to check 10MHz reference output. It looks not bad for me, but i'm not sure if harmonic levels are acceptable.

Next I connected spectrum analyzer to Port1, set VNA to single point measurements and made some observation through VNA's spectrum 300kHz - 4GHz. VNA generates pretty accurate frequency, but amplitude is bouncing like crazy. It's jumping from SA's noise floor to -10dbm. I've attached some screenshots in MAXHOLD and Average modes.

I opened the VNA. While I was wiping dust off the unit I noticed that one of the modules was marked "LO BAD" by someone. It was A130 SYNTHESIZER (p/n 1043.2999.06). I removed and opened this module to find some obvious faults. There was nothing strange besides two resoldered MC100EL33 (deviders by 4) and one strange looking part which I couldn't identify.
Also I tried to boot VNA w/o this module and it did. And it didn't show "LO-VCO faulty" error. But VNA wil not measure anything without this synthesizer (no way!)...

[s0r0s]

Follow up about that strange looking part. It has EPCOS logo, I believe. And "122". All external faces (beside one with central contact) of this past are conductive. There is a hole through whole body and the central contact is inserted there. Now this part behaves as a short circuit between central contact and body. There is a rainbow-like discoloration on part's body which makes me suspicious about this part. I suppose it's some sort of fuse/protection device.

Now I'm asking community for any help. Service manual, recommendations how to deal with a fault is highly appreciated.

[SeanB]

That looks like a ceramic filter, which would probably appear at DC to be a short, but at 800MHz or so it acts like a very nice filter or resonator, and probably is the oscillator for the IF stage.

[eb4fbz]

That's a ceramic resonator, and the discoloration is normal due to copper layer oxidation.

[KJDS]

If you ever get it working, then it's likely you'll throw it out of the window once you discover the delights of its user interface.

[s0r0s]

SeanB, eb4fbz Thank you for your hints. These type of devices are called ceramic coaxial resonators. Looks like EPCOS doesn't make them any more.

[s0r0s]

A small follow up to this repair project.

So I made extension cables to be able to probe the faulty board on top of the VNA. Found out that it has system power supply of +15V, -15V, +5V, +28V.
Then I took several photos with thermal imaging camera. It helped with finding suspicious regions within VCO AUX can.
Now I'll describe what I found in each can:

1. VCO AUX
RF output of this can has a clean and stable peak of 1010MHz and 10dbm.
There are 2 NE5534 opamps. I think they are dead. The negative supply rail is -14.9V, but the positive one is +25V. And I couldn't find where these 25 volts come from. There are also hot transistors and resistors.

2. VCO LOCAL
It's very similar to VCO SOURCE can. They both have MGA1 module, similar schematic but different topologies.
By default, this VCO generates nothing at RF port. There is a NPN amplifier BCP68 as power supply for MGA1 module. It outputs ~1.6V. I measured the same part in VCO SOURCE can and with the same base (13.5V), collector (14.9V), emitter voltage is 12.7V. So when I applied 12.7V from external power source, I could see a peak of 1668MHz, unstable by frequency and amplitude.
This can has a pair of NE5534 op amps on the back side. The negative supply rail is -2.5V, the positive one is 0V (short with ground). Doesn't sound right.

3. VCO SOURCE.
It has 2 RF ports. The one on the right is 10MHz reference input and used to lock at least VCO SOURCE and VCO AUX output.
The other RF port is used as stimulus generator of VNA (at least at VNA's Port 1). Within sweep region of 1-2GHz it is exactly the same, in other regions (0.3-1GHz and 2-4GHz) signal is mixed (or divided or multiplied). This can also has a pair of NE5534 op amps on the back side. The negative supply rail is -2V, the positive one is 24.6V. Doesn't sound right either, probably are both dead.

4. CANS WITH DIGITAL STUFF
There are many of them. Each can has it's power supply regulator based on BCP68 and I couldn't find any failure.

That's all for now. Still looking for service manual. There are several test points on this board and I wish I could verify them.

[s0r0s]

During another day of probing and sniffing, one more dead transistor was found. By replacing this transistor with external power supply I managed to make my VNA work. No more errors. Tested it with filters, antennas. Works like a charm. Now I'm waiting for replacement parts.

I'm also going to replace dying HDD with SSD (Compact Flash based). My unit runs some king of realtime OS, but latest measurement application available from R&S should be run under WinNT/Win2000 environment. I heard that there are come king of unique calibration files available for each unit and I need to copy these files to new SSD. Does anybody know which files I need to copy?

[s0r0s]

Is anybody here familiar with HDDs for that not so fresh R&S equipment?
I'd like to replace HDD in my ZVR, but I can't even make a working copy of HDD. My HDD has 2 FAT16 partitions:
1st - 443MB - contatins DOS and firmware (measurement application). Also has Windows 3.1 folder but never boots it;
2nd - 40.3MB - contains iRMX.
As I understand iRMX runs DOS as a process and don't understand why R&S made this so complicated.

I tried Acronis, Norton Ghost, Paragon Partition Manager. All this tools produce a "copy", which my ZVR fails to boot from. The tool by Paragon produces bootable drive, but ZVR doesn't see the partition with DOS and fails to boot into firmware. I can see both partitions  by connecting duplicate drive to my PC. Other tools make copies ZVR doesn't understand.

Also I wish I could replace DOS and old firmware with Windows NT (or Win2000) and latest firmware.

If someone has drive images and/or instructions how to work with this drives, it would be very appreciated.

[orion242]

Somewhat surprising all the other imaging tools couldn't make a copy.

Clonezilla is my tool of choice, and free.  Wonder if they put some errors on the drive as a form of copy protection and these tools are "fixing" the error that R&S is looking for.

[cs.dk]

SelfImage can clone weird drivesetups/partitions. Had to use it for a HP Digital Sender once. It had 4 or 5 partitions with some unused space between them. If they are cloned with usual software, the DS won't recognise the drive and refuses to boot.
http://www.pariswells.com/upload/SelfImage-121.zip
Some clonesoftware is also able to clone 1:1 with a parameter.

[s0r0s]

Thank you a lot! That SelfImage tool really works. I made a copy of original 1.6GB drive to 28GB HDD. When it successfully booted, I made a copy to 8GB Compact Flash card. And it also booted!
Program minimum accomplished.

Looking for ZVR/FSEA/FSEB windows based images to assemble something working for my unit.

[matt123]

 Soros, would you happen to have a copy of that HDD image? I got one with no HDD and have been going insane trying to get this thing to work.

 Thank you,

Matt

[s0r0s]

Sure! I'll upload it. Stay tuned.

[sky2city]

My ZVR is blocked in " Dowbload LCA "(refer to the photo posted), then I reboot it( turn off and then turn on after a couple of seconds), it pass " Download LCA".

Is there anyone know what the problem is?

thanks advance.

Roger

[atwoz]

Hello S0r0s,

is your unit still working? Were you able to successfully clone the HDD?? I just bought a used ZVR for $3000 USD and want to know your opinion on the unit.

Thanks!!

[s0r0s]

Yep, I successfully cloned the hdd with SelfImage tool and replaced HDD with CF card.
I had a bigger plan to upgrade ZVR's OS to WinNT and even add USB support. I couldn't accomplish this goal as I didn't find any image with WinNT.
Still like what I got. It's R&S, I got it for cheap, it came with adventure inside.

[sky2city]

Hey S0r0s,

I have one winNT OS of ZVR, I can't send it to U. But its size is about 300Mbits.
contact me by email if your are wanna it, sky2city@163.com

Roger

[sky2city]

Hi PAL,
Is there anybody know how to clone the disk of ZVR?
The HDD of my ZVR is dying and I have to backup and clone it to another HDD.
I had tried "Selfimage" tool running on winXP and "ddrescue" tool running on Ubuntu, without lucky, both is fail. 
the error said "DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER"

So it there anybody have clone the HDD sucessful? and it is so much thanks to whom, tell me the exactly step?
thanks advance.

Roger


 

[Kilo Tango]

Hi, I managed to do it using a Linux machine and a GUI version of DDrescue see https://www.eevblog.com/forum/testgear/rohde-schwarz-fsiq26-well-almost/msg1334106/#msg1334106 I think there is something about Win NT disks being put into other versions of windows, they upset something. As well as on my FSIQ, I managed to do the same for my ZVK.

Best of luck,

Ken

[Gerhard_dk4xp]

I also did it for my 54846B scope. I removed the disk from the scope,
attached it with a ATA/Sata to USB cable to an USB3 port of my Linux
laptop and did

dd if=/dev/sdc of=A54846B_safety_copy  bs=1M        with the old disk

and then

dd  if=A54846B_safety_copy  of= /dev/sdc  bs=1M      with the "new" disk

USB3 port because it delivers more power.  Block size = 1 Meg makes it faster.

The "new" disk had abt. 2 years of service in my old Dell Inspiron.
It was larger than the original of the scope, that did not matter.

I had to do it in a few chunks, since the original disk failed once
it had normal operating temperature. Putting it into the fridge
helped enormously.

( I have once recovered an IBM Death Star SCSI disk in this way,
it needed the deep freezer!     )

Cheers, Gerhard

[sky2city]

Hi, I managed to do it using a Linux machine and a GUI version of DDrescue see https://www.eevblog.com/forum/testgear/rohde-schwarz-fsiq26-well-almost/msg1334106/#msg1334106 I think there is something about Win NT disks being put into other versions of windows, they upset something. As well as on my FSIQ, I managed to do the same for my ZVK.

Best of luck,

Ken

Hi Kilo Tango，
Do you remember the setting of the GUI version of ddrescue?

[Kilo Tango]

Hmm, I just did it, used default settings. The settings you show look fine.

I think the thing is DDrescue does a bit for bit copy so what you get is the same as it was. If you put the drive in a windows machine then it writes something to the partitions and stops it booting when you refit it.

Ken

[sky2city]

Hi Guys,
I got the solution finally. Thanks all of you.

I will post it later on. Given that the CPU fan sounds terrible, I am worry about it a lot.

I can' t find any Fan to replace it since that is a really old one.

if I can not replace the fan, I may add lubricate oil to reduce the noise from cpu fan.

Roger@2018-06-15

[Samogon]

Old fans usually become noisy due to worn bearings and lubricating doesn’t help much.