Author Topic: W&G sna-20/23 spectrum analyzer repair (Read 13919 times)

aseok · « **on:** September 30, 2019, 06:23:15 am »

Hi.
I have a sna-20 and sna-23 spectrum analyzers from wandel & goltermann, both facing problems and need repair.
sna-20 has hard drive controller failure error.
sna-23 has problem of sending incorrect lcd data and hdd related problem.
both have compensation data floppy disks but problem doesn't solve by running compensation software.
Has anyone experience of repairing these systems?

aseok · « **Reply #1 on:** November 29, 2019, 11:50:30 am »

After inspecting for a couple of days and replacing some parts, it seems that i need installation firmware of these SAs, say, SNA-20 and SNA-23.
Does anyone have the related firmware/floppy disks?
Thanks.

kyndbo · « **Reply #2 on:** December 29, 2019, 06:18:32 pm »

HI aseok,
Can I get a copy of your compensation data floppy disks ?
I have a SNA 23 , but no boot disk, I have changed backup battery, but would like to try to boot from floppy disk,
to restore my data in B: drive ,
I woud like to share our findings with our analyzers, and solve them,

regards helge

kyndbo@gmail.com

aseok · « **Reply #3 on:** December 30, 2019, 04:55:40 am »

As you know, all floppy data sectors must be copied and pasted in a floppy to work.
What is the hard drive of sna 23? does it boot from cf card?

Qw3rtzuiop · « **Reply #4 on:** October 26, 2020, 07:20:27 pm »

Hello guys,

were you able to repair your analyzers?
Ive repaired one of these lately and uploaded photos and the hdd backup to xdevs.com.
But my SNA23 is from the H series without the ram. Just one HDD.

All the stuff is here:
https://xdevs.com/doc/WG/SNA23/

Gerhard_dk4xp · « **Reply #5 on:** October 26, 2020, 10:51:19 pm »

I have a SNA-33 that has a floppy and a battery-powered ramdisk. It still
boots, but I was thinking that I had destroyed the input. Seems not to be
the case, but it is still completely deaf. I must look into this soon now,

Gerhard

Qw3rtzuiop · « **Reply #6 on:** October 27, 2020, 09:52:30 am »

Quote from: Gerhard_dk4xp on October 26, 2020, 10:51:19 pm

Seems not to be
the case, but it is still completely deaf.

My unit was also completly deaf. The trace was visible but no signals. The error was the missing -6.8V power supply rail. There was a broken diode in the power supply. After changing the diode the unit worked flawless again

aseok · « **Reply #7 on:** November 17, 2020, 02:39:24 pm »

Hi
Would you please send a picture including HDD attached in place? my sna23 is missing hdd and i thought that the compact flash is the main memory.
Thanks.

Qw3rtzuiop · « **Reply #8 on:** November 17, 2020, 05:01:08 pm »

There is an HDD image here:
https://xdevs.com/doc/WG/SNA23/hdd%20backup/

You can burn it with HDD Raw Copy Tool

aseok · « **Reply #9 on:** November 17, 2020, 05:50:26 pm »

my sna23 is f series, is it compatible with your image?

aseok · « **Reply #10 on:** November 17, 2020, 06:38:15 pm »

Is it the hdd connector? another point is that i have a 60GB hdd, can i use that?

Qw3rtzuiop · « **Reply #11 on:** November 17, 2020, 09:05:07 pm »

Yes that is the IDE connector. I dont know if the image will workfor you but there are good chances. But a 60gb HDD will not work.
I noticed that just 512mb are working correctly. There is a limit defined by the bios. I installed a CF Card to IDE adapter with a 512 MB card.

aseok · « **Reply #12 on:** November 18, 2020, 08:59:54 am »

What does cf card do beside hdd? is it necessary?

aseok · « **Reply #13 on:** November 18, 2020, 06:17:20 pm »

As the connector is 50 pin, how should 40 pin ide connect to it?

Gerhard_dk4xp · « **Reply #14 on:** November 18, 2020, 06:26:37 pm »

Maybe SCSI???

Qw3rtzuiop · « **Reply #15 on:** November 18, 2020, 07:08:49 pm »

It is IDE. The spare pins are not connected or connected to the hdd jumpers.

aseok · « **Reply #16 on:** November 19, 2020, 07:42:09 am »

Quote from: Qw3rtzuiop on October 27, 2020, 09:52:30 am

Quote from: Gerhard_dk4xp on October 26, 2020, 10:51:19 pm
Seems not to be
the case, but it is still completely deaf.
My unit was also completly deaf. The trace was visible but no signals. The error was the missing -6.8V power supply rail. There was a broken diode in the power supply. After changing the diode the unit worked flawless again

Would you please send a video of your sna from booting up to main software start?
Thanks.

Qw3rtzuiop · « **Reply #17 on:** November 19, 2020, 08:52:38 am »

Here is the a video of the start up:
https://youtu.be/-rusvtIUkgI

NIKGEROS · « **Reply #18 on:** November 19, 2020, 11:14:17 am »

Hello everybody,

in case somebody could advise : I have a SNA-23 and facing BOOT problem. I use the disk but when the process is finished it keeps looping again asking for the disk.

thanks a lot,

Nikos

aseok · « **Reply #19 on:** November 19, 2020, 01:07:13 pm »

Quote from: Qw3rtzuiop on November 18, 2020, 07:08:49 pm

It is IDE. The spare pins are not connected or connected to the hdd jumpers.

does 40 pin ide connect at the middle of 50 pin connector, symmetrically?

aseok · « **Reply #20 on:** November 19, 2020, 01:09:38 pm »

Quote from: NIKGEROS on November 19, 2020, 11:14:17 am

Hello everybody,

in case somebody could advise : I have a SNA-23 and facing BOOT problem. I use the disk but when the process is finished it keeps looping again asking for the disk.

thanks a lot,

Nikos

Hello
What is the version of your sna? what is main memory?

Qw3rtzuiop · « **Reply #21 on:** November 19, 2020, 06:14:44 pm »

Quote from: aseok on November 19, 2020, 01:07:13 pm

does 40 pin ide connect at the middle of 50 pin connector, symmetrically?

No. Take a look at that picture i posted. You need to connect it at the 44 pin side. Just leave the 4 power supply pins empty. The 4 power supply pins are on the left side.

aseok · « **Reply #22 on:** November 20, 2020, 06:00:06 am »

Quote from: kyndbo on December 29, 2019, 06:18:32 pm

HI aseok,
Can I get a copy of your compensation data floppy disks ?
I have a SNA 23 , but no boot disk, I have changed backup battery, but would like to try to boot from floppy disk,
to restore my data in B: drive ,
I woud like to share our findings with our analyzers, and solve them,

regards helge

kyndbo@gmail.com

Hi kyndbo
Which version is your sna? does it have dram module?

aseok · « **Reply #23 on:** November 20, 2020, 08:44:00 am »

Quote from: Qw3rtzuiop on November 18, 2020, 07:08:49 pm

It is IDE. The spare pins are not connected or connected to the hdd jumpers.

which pins are 1 and 44?

aseok · « **Reply #24 on:** November 24, 2020, 11:16:49 am »

There is a project RASCSI that uses raspberry pi as scsi hard disk emulator and is originally written and tested for sharp x68000 & mac pcs. i wonder if we can use it with our SNAs.

https://github.com/akuker/RASCSI

NIKGEROS · « **Reply #25 on:** December 17, 2020, 06:34:03 am »

Hello again , best greetings to all.
I think you need the model and is SNA-23 with a 8 MB memory....

tnx a lot

NIKGEROS · « **Reply #26 on:** March 09, 2021, 11:18:54 am »

Hello again !
Think I'm facing same problem here...Probably have f series SNA23...not a HDD....
Post some pic....In case somebody resolved that pls inform !

Take care

Qw3rtzuiop · « **Reply #27 on:** March 09, 2021, 02:38:34 pm »

Your HDD is probably dead. If you install an new one you can use the image from xdevs.

NIKGEROS · « **Reply #28 on:** March 11, 2021, 07:39:00 am »

thank you so much !

take care,
Nikos

NIKGEROS · « **Reply #29 on:** March 16, 2021, 12:42:09 pm »

My model is C series...I can not find a HDD....Do you have any suggestions ?
thank you

Gerhard_dk4xp · « **Reply #30 on:** September 01, 2021, 11:07:18 am »

The C series does not have a HDD. Instead it has a lithium-buffered CMOS RAM. The Lithium battery is the orange Renata thingy on the larger top board. There is also a Dallas 12887A realtime clock chip with some CMOS RAM that has an internal Lithium battery that may go empty. It is used to keep the bios settings in the usual PC AT way. Changing the CMOS RAM battery should be done with the SNA33 powered up, otherwise the content of b: is gone for good. (Supposed the Li Battery is not yet empty.)
I have found the user manual, service manual and schematics somewhere as PDFs.

Gerhard_dk4xp · « **Reply #31 on:** September 13, 2021, 09:31:34 am »

There is more to the disks. (My serial number is D0029.)

For those without a real harddisk, C: is an array of Flash eproms that can
be written with an utility from the service disk. It is R/O to the normal user.
B: is the lithium buffered cmos ram for user results and calibration factors.

I also get the message that the HD controller is broken. But when I boot
from floppy, I can see the contents of C: , so this seems to be more a
driver issue. I cannot boot completely into the measurement program.
All floppies must be dos6.22. Everything else seems to produce
wrong_version errors. Some .com and .exe and .sys files are incompatible
when taken from different dos versions.

I replaced both the Renata Lithium battery and the Dallas Li buffered real time
clock and managed to erase b: during that, should not do that in the night.
I then tried to set the clock and disk type in the Dallas chip. I could find the required
disk type nowhere in documentation. I finally restored the original Dallas chip,
and it seem not to be completely empty.

It contained HD type = 8, which is
Cyl 995 heads 14 WPCOM 65535 LZONE 995 sect 17 Size 116 MB

Funny enough, the old Dallas had the same time that I set with the new chip,
but I think I must not understand everything. In NIKGEROS' case, the
Dallas chip seems to be empty because it has forgotten the date/time.

I could not get an original Renata battery in time, so I cracked the old one open
and soldered wires to the leads of the carrier. Don't solder directly to a Lithium
battery that does not have wires or tabs, that might result in a thermonuclear surprise.
I used a 2/3 AA cell with wires, ugly but works.

Sometimes, I also get the display with the zebra stripes from the first post,
so this is not a hardware malfunction. Also, my reconstructed boot disk has a
problem with the display window size. I cannot see the bottom line, so typing
commands is a royal pain.

The Wandel&Goltermann fan group on groups.io seems to be dead.
I see there abt 3 posts, and my test post never showed up.

cheers, Gerhard

alexturner · « **Reply #32 on:** October 21, 2021, 11:02:38 am »

Thanks for all the information and contribution in this thread - I bought a SNA-23 today with the same HDD controller issue. I opened the box up onto to not be able to find a HDD, so I'm assuming I have a flash model. I've bought a USB Flash to Floppy adaptor which is the same form factor as a floppy disk drive, so I might upgrade the box with some modern hardware, we'll see if it works...

Gerhard_dk4xp · « **Reply #33 on:** October 24, 2021, 01:37:32 am »

congratulations!

Make backups of the software on it before you start playing with batteries,
and also the bios settings.
(I would appreciate a copy :-) it fits into an email nowadays.)
Maybe we should have a repository somewhere of the essential disks and proms.

I have paused the work on mine, tried to set up a different computer with DOS6.22
and a real hard disk, but it keeps power cycling. The kind of results you get when
trying to revive hard & software from the early monolithicum.

And don't think that "format" from 6.0 works with 6.22. It just says "wrong version"
but not what version it is, let alone what it wants.

cheers, Gerhard

Gerhard_dk4xp · « **Reply #34 on:** October 24, 2021, 01:42:16 am »

BTW I tried to contact the owner of the WG group on groups.io.
No response yet.

Gerhard

alexturner · « **Reply #35 on:** October 24, 2021, 06:26:16 am »

Thanks Gerhard!

So are you saying that the WG software is based on DOS 6.0? I'm having a very difficult time making a boot disk, naturally if I dump linux (All in One) onto a floppy it boots fine, but getting DOS or these files in the "Service Disk" on XDevs to boot is another issue entirely. Does anyone have a .img file of the service disk I can just _dd_?

Alex

Gerhard_dk4xp · « **Reply #36 on:** October 24, 2021, 09:14:37 am »

I think it is 6.22.
I can send you my files, but no guaranty that anything works.
My address is #dk4xp#at#arcor#.#de

Cheers, Gerhard

Gerhard_dk4xp · « **Reply #37 on:** October 24, 2021, 10:05:04 am »

Alex, the mail to you bounces b/c of dangerous contents, even with zips.

alexturner · « **Reply #38 on:** October 24, 2021, 10:13:05 am »

Hmm, that's weird. Maybe easiest to upload to Google drive and share the link or dropbox?

alexturner · « **Reply #39 on:** October 24, 2021, 11:47:58 am »

So having not properly read the service manuals I thought there was reference to my HDD Controller Issue being connected to the SRAM B: drive. I managed to get a DOS 6.22 disk imaged and copied the service disk files across. In the process I have formatted my B: drive, whether or not it was already empty is another question entirely. DIR on B: read nothing previously and after the format. The seller of this unit mentioned that when he bought it, it came with floppies which he may still have and is in the process of packing up everything in his house, so we may have luck there.

I have the same challenges as Gerhard. I can boot into a DOS disk and see the contents of the C: drive, however, the unit won't boot citing a HDD Controller Error. Not sure what to do next

Gerhard_dk4xp · « **Reply #40 on:** October 31, 2021, 05:31:13 pm »

Sorry, I've been away for a week. The DOS files for the SNA are under:

< http://www.hoffmann-hochfrequenz.de/downloads/sna_arch.zip >

Seems like it is classified as a security risc also here but can be overridden.

It won't stay there for long.
Looks like I have work to do on my web site.
Gerhard

alexturner · « **Reply #41 on:** November 02, 2021, 12:24:46 pm »

Thanks Gerhard,

I've downloaded it and am compiling a bunch of disks I'm slowly getting access to. I'll create a repo somewhere to share when I get it working.

On booting your disk I noticed the the same banding issue as the OP. I saw this was also the case when I started the SNA software from the C: drive from a DOS 6.22 disk. In breaking into a DOS shell with ALT+F10, I saw the debug errors which all cite the missing contents of the B: drive, I suspect these will go away when I get the image. By some stroke of luck I'm in contact with the person who has my calibration disk and hopefully I'll see it this week, we'll see.

I'll report back with status none the less.

Alex

alexturner · « **Reply #42 on:** November 03, 2021, 10:50:56 am »

Does anyone have more of an idea about the zebra banding that occurs after the main-sw loads? Looking into the fairly scarce service manual it appears as if the AT board boots using VGA BIOS, however when the application loads there is a faster, application specific TI graphic chip that takes control and it's at this point the banding appears; so I suspect an issue here. The graphics board (BSK-3) is quite sophisticated and includes a switch to direct video to the EL display or the RGB TTL port on the rear of the unit. I suspect my best course of action is to purchase a TTL to VGA adaptor and see if I can get an image out the rear port (the diagnose switching, etc).

If not it appears the unit might be dead on a count of there being a couple of critical FPGA's which drive the EL display that firmware will be long lost to.

Have any of the original posters on this thread who have had banding issues on boot resolved this?

Alex

alexturner · « **Reply #43 on:** November 15, 2021, 12:55:21 am »

Does anyone have the install disks??

Gerhard_dk4xp · « **Reply #44 on:** December 26, 2021, 03:56:06 am »

On microcontroller.net there appeared someone asking a question and in the context
it was clear that he has a working SNA23/33. I asked him for the floppy images but he
never resurfaced.

Tonight I took a floppy whose bit image is in the sna_arch.zip file that you should
have got. It tries booting into DOS but cannot find
\DOS\himem.sys
\DOS\country.sys
\DOS\ANSI.sys and at least 2 other files.

The files are on the disk but there is no \DOS directory.
So I made one and COPIED them to that directory. The 1.44MB floppy is only abt.
half-full, and I copied also some more that are mentioned in config.sys and autoexec.bat.
I also commented out the first or second line in autoexec.bat that hides the commands
that are executed. I want to see them.

The floppy then booted into dos but I got the Zebra screen again.
I then rebooted and aborted it just before the W&G-specific things are started.
(many CTL-Cs). That left me with a working DOS command line.
I can make DIR C: or DIR B: and get the contents listed. That means that the flash disk c:
and the ram disk B: are OK. I also did chkdsk c: and that worked ok.

Nevertheless, when I try to boot without floppy it says the hard drive is broken.

The bottom 2 or 3 lines of the built-in screen are missing, that's a royal pain. Use some
CR to see all the answers. Maybe a ANSI.sys param is wrong.
And I have a German keyboard while the system expects US.
That can probably be healed with the right parameters to country.sys. I wished I still had
my dos handbook.

I used a HAMA USB floppy drive to mount the floppy under Linux. The port must be
USB3 because that delivers more current to the floppy drive; else seek errors abound.
I'll make some screen shots tomorrow, too tired for now.

Cheers, Gerhard

alexturner · « **Reply #45 on:** December 26, 2021, 11:06:17 am »

Thanks Gerhard!

So the SNA23 has two video controllers, a VGA graphics driver which is boots from, and another more advanced graphics processor which is used once the SNA software starts to drive the EL display. The issue (the Zebra lines) surfaces when the SNA software instructs the graphics card to switch and enable the EL display. I was able to validate this by running a command named BSK3 or something similar (which is the name of the graphics board). A more detailed explanation is available in the service manual.

I'm still not sure what these Zebra lines are about. I'm so surprised how few people have these and know much about them. They're such wonderful examples of engineering and it's a shame that our units are destined to sit on the shelf forever until more data surfaces. At this point, I'm looking for the install disks which should be floating around the ether somewhere - sounds like you'll benefit from them too but we'll see!

Alex

Gerhard_dk4xp · « **Reply #46 on:** December 26, 2021, 01:35:40 pm »

I think the zebra banding is just uninitialized video ram; I have seen
similar effects with DRAMs fresh from power up.

At Leasametric they claimed a SNA33 did cost > DM100k anew, that
would be > €100000 now. 26 GHz and 1 Hz resolution BW.
Just build such a synthesizer.

Pude · « **Reply #47 on:** March 24, 2022, 12:56:10 pm »

Hello everybody,

I got a W&G SNA-33 from ebay yesterday and it has this problem with file system. It complains briefly about HDD controller.
I already hacked a new battery for Dallas RTC and Renata battery has voltage little over 3 V. Now I'm looking for a suitable boot disk for this. The disk drive works but I'm trying to use Gotek because the ease of use. I read this thread and maybe someone of you have some boot disks to start with? This machine didn't include any of those. If so I'll like to have an image, please. I tried a normal ms-dos 6.22 boot image, but no luck. Just for fun I tried to boot from an old Red hat linux disk, but it was for a machine I've scrapped many many years ago.

This machine does likely have flash version of C-drive. So any hints would be useful. Next I'm trying to find a keyboard for this, PS/2-kb should be fine? Some pictures below.

Gerhard_dk4xp · « **Reply #48 on:** March 24, 2022, 02:30:48 pm »

Welcome to the club!
I have made no progress in the meantime.

My keyboard is an old AT02 keyboard, cloned by Cherry. Works.

It is weird, that when booting it says that the c: drive is defective,
but when I boot from floppy and stop the autoexec.bat early enough,
I can see contents of c:

Booting from what I considered a boot floppy leads to the zebra screen.

Gerhard

Gerhard_dk4xp · « **Reply #49 on:** March 25, 2022, 10:06:30 am »

This does work also. PS2 keyboard + adapter cable.

What is the bios disk type of C: on your unit?

Gerhard

Pude · « **Reply #50 on:** March 25, 2022, 10:45:35 am »

I attach the screen captures of my bioses. VGA bios is different from Amibios I think.

robots · « **Reply #51 on:** May 09, 2022, 08:12:34 am »

Hi,

from what i understand in bios you should select harddisk as NONE! The memory board (with flash memory) has its own bios that gets loaded and hooked to the main bios as harddisk controller.

Its also written in the service manual :-)

Gerhard_dk4xp · « **Reply #52 on:** May 10, 2022, 11:24:46 am »

I have set it to disk type "none" and now it boots from
the disk replacement right into the zebra stripes.

Funny enough, the disk type used to be 8, just like
the photos by Pude and NIKGEROS.

Gerhard

Pude · « **Reply #53 on:** May 10, 2022, 05:05:59 pm »

Thank you @robots about that hard drive setting info. I'll set it later.

Some progress with my SNA-33:
- I made RGBtoHDMI-board to work together with Raspberry zero. Actually I made a few of those. [pic 1]
- Connecting RGBtoHDMI to SNA's EGA monitor connector I got signal out! [pic 2] Picture changed when pressing buttons and all that stuff so the software is working properly. Monitor signals are bad.
- But EGA picture frequency was something not to be viewed properly. Sometimes when I tried to change some RGBtoHDMI settings picture was even readable! [pic 3]. But normally it was just rolling all the time.
- I started to check signals on the Monitor controller board underneath the main processor board. I think that some chip(s) are bad there. This is in work in progress state. Here I've soldered wires in the legs of U46 chip. That's PAL chip but I have to add more wires in other chips too to get proper understanding about frequency prosessing. [pic 4]

Otherwise I boot my SNA from USB stick to MS DOS. Then change drive C: and run autoexec.bat. I think the file system is correct and working ok. I'll take some backups later and upload those some place.

Storm · « **Reply #54 on:** July 20, 2022, 10:06:43 am »

Hi guys,

I currently have a SNA-23 H-Series in Restauration and would like to ask if someone here in the forum has access to the respective Service Manual and/or User Manual?

BTW, the Zebra-Stripes come from uninitialized LCD Controller. It is Part of the DOS-Boot process and normally initiated by a batch file. I am currently working on replacing the HDD with a flash DOM, which works only with a specific drive-type. I noted that it is not possible to save newly detected HDD types to CMOS-RAM, my SNA-23 always defaults to a specific HDD-config. Does anybody else with a H-Series Model see this as well?

Storm · « **Reply #55 on:** August 21, 2022, 03:58:38 pm »

Gerhard and all others owning a SNA-20/23/30/33 Series A..E:

I had the same problem with the zebra stripes with a C-Model after the Dallas RTC with SRAM and Li-Battery was completely empty. I did not yet modify the dallas chip with well-known external battery mod, but pressed DEL (or CLR on internal keyboard) on my external keyboard during bootup to enter the BIOS. Then I modified the Standard BIOS setting for HDD C: to „Disabled“ (from the default setting „8“). Hit ESC, and then ALSO enter the Advanced BIOS. Here I set the Shadowing to NONE or Disabled (default value BOTH is wrong!)
Hit ESC, selected „Save to CMOS and exit“, confirmed with „Y“ and now it reboots.....
DO NOT SWITCH OFF THE SNA!
My SNA-23 now boots from C: (my orange Renata Battery is still working), starts the measurement SW, AND....
TADA...
shows the spectrum!

NO ZEBRA ANYMORE

Looks like the Zebra-Effect comes from a memory conflict of BSK-3 with enabled BIOS shadowing.

The service manual even mentions that shadowing must be disabled, otherwise conflicts will occur.

So as a Conclusion:

Whenever your Dallas Battery is empty and CMOS writes will not be stored anymore, remember to set HDD C: to disabled in Standard BIOS and Shadowing to disabled in Advanced BIOS, after installing a fresh battery.

Hope this helps to get rid of lots of zebra cases out there.

Pude · « **Reply #56 on:** August 21, 2022, 06:34:11 pm »

A HUGE thank you @Storm!!!

That advanced bios setting was the thing. Finally got this SNA to signal screen. Still calibration data missing from B-drive, but I've seen that data there in place. Some more tweaking and I have properly working device.

Thanks!

Gerhard_dk4xp · « **Reply #57 on:** August 21, 2022, 07:19:41 pm »

Works for me, too. :-)
But the behaviour of the sweeps is still somewhat special. Not like it used to be.
I'll look into that tomorrow.

BTW one of the differences between sna23 and 33 is the fundamental mixer.
That must imply a different synthesizer.

Cheers, Gerhard

Electro4lease · « **Reply #58 on:** September 29, 2022, 03:47:08 pm »

Hello All,
Just new on this forum...
We're a french company specialized in the resale of used test & measurement equipments
We have a W&G SNA-33 whose CPU board shows traces of corrosion and we don't have time to repair it.
If someone in interested in this unit, please contact me before we sell it on ebay for parts.
Br.
Antoine

Pude · « **Reply #59 on:** September 30, 2022, 07:12:25 am »

About my SNA-33:

I think, all thought the orange battery shows decent voltages(little bit over 3 V), some settings and data is lost quite frequently from my bios and drive. Time stays in the bios but year is 100 years off every time, but that is y2k.

And I have to set those hard drives all over again as described above. Also the unit doesn't start in many cases.

I managed to reformat B-drive and I put the salvaged calibration data back there. Now my unit sweeps but shows bulky graph like in the pic here. Clearly it is curly because the calibration data but no actual signal there.

I contacted @Electro4lease to buy a spare parts unit. And some day, some day my SNA-33 will be fully functional.

Gerhard_dk4xp · « **Reply #60 on:** September 30, 2022, 10:42:45 am »

The date and bios data are all handled only in the Dallas clock chip.
Have you re-batteried it and broken something in it?

The orange battery plays no role in this.

I have just taken the SNA-33 on the table again and saw that I have damaged
an U.FL or SMP plug on a thin coax that comes from the yig filter :-(
No Idea where it belongs. I'll take more photographs!

Pude · « **Reply #61 on:** September 30, 2022, 11:13:42 am »

Yes it is possible that I've done something wrong while adding button cell into Dallas RTC. It was just a quick fix and have to look into that more. This cell is parallel to original battery. I have not finished this as you may see in the picture, the cell is flapping around in the breeze.

dxl · « **Reply #62 on:** September 30, 2022, 03:27:44 pm »

So i bought the SNA-33 from electro4lease - they sent me pictures of the damage, and it's yet another bloody battery corrosion issue. I guess the mainboard is non-repairable. Not sure how often these boards show up, but i guess not often. So would be interesting to transplant another mainboard in there, but that would likely require a lot of reverse engineering how the interface to the SA looks like.

dxl · « **Reply #63 on:** September 30, 2022, 06:22:14 pm »

The 'hdd backup from H series' has two interesting files:

GERPC.MAP - map file with all the function names for the pc software
ZZDSP.MAP - map file for the DSP

I haven't checked whether they match the GERPC exe file, but it gives at least an idea what functions are present...

EDIT: After a quick check it looks like it's matching GERPC.EXE. So happy reverse engineering!

Pude · « **Reply #64 on:** September 30, 2022, 08:58:29 pm »

Welcome @dxl to this SNA-33/20/23 club. You were a little bit faster buyer than me. My lunch break was too much.

But anyway this troubleshooting is always nicer with larger group.

dxl · « **Reply #65 on:** September 30, 2022, 09:06:58 pm »

Quote from: Pude on September 30, 2022, 08:58:29 pm

Welcome @dxl to this SNA-33/20/23 club. You were a little bit faster buyer than me. My lunch break was too much. But anyway this troubleshooting is always nicer with larger group.

Thanks!

Let's see whether it was a good idea - the picture of the CPU Board looks really bad...

Pude · « **Reply #66 on:** September 30, 2022, 09:20:20 pm »

Quote from: dxl on September 30, 2022, 09:06:58 pm

Thanks!

Let's see whether it was a good idea - the picture of the CPU Board looks really bad...

Yes it does. I got those pics also. Really careful re-tracing work under microscope...

Have you searched that damaged PicoPower chip next to battery leakage. What is it?

dxl · « **Reply #67 on:** September 30, 2022, 09:30:33 pm »

That picopower chip is either north or southbridge. Seeing how many pins are vanished, i think it's impossible to repair that board. My guess is that it is easier to figure out the pin assignment of the DIN connector to the other board and put in another mainboard. The main problem seems to be the WD90C24 VGA controller. The W&G software seems to use the bit blitting features of it, so you cannot just put another graphics card in.

My silly idea for now is to put something like a raspberry pi in, forward the ISA traffic to the other board, and emulate the graphics in software. But that's a lot of work, and would take some time. Another option is trying to get a WD90C24 VGA card and use that with a normal processor board.

And there's of course the option of just waiting to get a replacement CPU card.

Main reason why i bought this unit is the fundamental RF mixing. I think there are not much other SA's out there doing that. The HP 70908 RF module does that as well, not sure about other SA's.

Gerhard_dk4xp · « **Reply #68 on:** October 01, 2022, 02:50:38 pm »

Hi, Pude!

I've made a new cable for the control current of the YIG filter.
Must be MCX connector. I had a cable I could sacrify.

Me thinks our analyzers do about the same, even in post-zebra times.
What looks like noise is not an actual measurement. The noisy peaks
happen at exactly the same places & same amplitude for every scan,
even if I change the frequency boundaries etc.

BTW my CPU board looks completely different. Mine is still based on
AM386, the one depicted above is 486. That's not good news since
that means more hardware differences between units on the market.

cheers, Gerhard DK4XP

Pude · « **Reply #69 on:** October 01, 2022, 03:43:05 pm »

Yes, my mainboard is based also on the AMD386sx. Btw. I have not looked yet what is the chip missing from the socket near the processor. Might be some option.

Gerhard_dk4xp · « **Reply #70 on:** October 01, 2022, 03:49:10 pm »

same like mine. Even the patch wire on the VG96 connector is the same,
and the empty socket.

dxl · « **Reply #71 on:** October 01, 2022, 04:05:25 pm »

Quote from: Pude on October 01, 2022, 03:43:05 pm

Yes, my mainboard is based also on the AMD386sx. Btw. I have not looked yet what is the chip missing from the socket near the processor. Might be some option.

Maybe for an optional i387 FPU?

dxl · « **Reply #72 on:** October 02, 2022, 09:24:54 pm »

Looking at the disassembly of GERPC.EXE from the H version, it looks like there is a command line option '-debugoutput' which seems to take either vga,com1,com2 or buff as argument.

EDIT: looks like this is rather a environment variable, so likely something like 'set DEBUGOUTPUT=X' in the startup batch file. where X is:

0 - VGA
1 - COM1
2 - COM2
3 - BUFF

However, it doesn't log much more in my QEMU. Maybe on real hardware, i don't know.

dxl · « **Reply #73 on:** October 02, 2022, 10:35:36 pm »

This is the debug output in my qemu:

Code: [Select]

selector of main() = 0x017F					 0:43:24
6283816 Bytes of memory available
main: SW-Version 3.13 on SNA 00000
5729456 Bytes of memory available
INTERNAL ERROR <0x0000>: Download error ZF-DSP 0x3001
CommunicationError TIMEOUT
	from ZF-DSP in ZF_Get_PegKorrLoc !
Error 0x3005 (TIMEOUT): ZF_DSP.ram_putLevelTab
Mm_FKorr_c: corrected gain for band 0 for -1.000dB
		min=0.000dB at 0GHz, max=6.413dB at 2.62GHz
Error 0x3005 (TIMEOUT): ZF_ram_putFreqTab
Error 0x3005 (TIMEOUT): ZF_ram_putFreqTab
Error 0x3005 (TIMEOUT): ZF_ram_putFreqTab
Error 0x3005 (TIMEOUT): ZF_ram_putFreqTab
INTERNAL ERROR <0x0000>: Download error Synthe 0x3001
CommunicationError TIMEOUT
	from ZF-DSP in ZF_Set_Vbw !
CommunicationError TIMEOUT
	from ZF-DSP in ZF_Bild_Init !
FATAL ERROR <0x3005>: ZF_DSP_Error in ZF_Handler
program terminated at						 0:43:30

INTERNAL ERROR <0x0000>: Error deleting Task "Messen"(ID: 44, Prio: 6)
	WGRM ERROR "critical task switch"

Of course it complains about the DSP Firmware download, it's all virtual, and therefore no hardware present...

Pude · « **Reply #74 on:** October 03, 2022, 04:41:12 am »

Here's my unit output from the screen.

Pude · « **Reply #75 on:** October 03, 2022, 04:50:17 am »

And here's my B-drive zipped including calibration data.

dxl · « **Reply #76 on:** October 03, 2022, 08:53:59 am »

With the H series software i see accesses to 9000:XXXX and D0000:XXXX segments, which might be the DSP. Any BIOS settings that might interfere with these ranges? (Not sure whether the old units are using the same range)

dxl · « **Reply #77 on:** October 07, 2022, 05:42:28 pm »

Received my unit today. As expected, no way to repair that board. Googling for the type suggested that "CSS Industrie Computer GmbH" seems to be the manufacturer. Not sure whether that's also true for the 386SX based boards.

https://www.industriebedarf.de/firmen/kaufbeuren_css_industrie_computer_gmbh.htm

Pude · « **Reply #78 on:** October 07, 2022, 05:53:03 pm »

Quote from: dxl on October 07, 2022, 05:42:28 pm

Received my unit today. As expected, no way to repair that board. Googling for the type suggested that "CSS Industrie Computer GmbH" seems to be the manufacturer. Not sure whether that's also true for the 386SX based boards.

My mainboard is done By W&G inc USA.

dxl · « **Reply #79 on:** October 10, 2022, 04:26:37 pm »

Some progress on my side...

With a lot of googling, i figured out that the Wandel & Goltermann ANT-20 "Advanced Network Testers" are using the same types of Motherboard. They existed in a lot of varieties from 486DX2 (the one i want, because it's the same as the one in the SNA) up to Pentium II boards. So i searched on ebay for such a unit. Unfortunately you cannot really see from the outside the exact type - the only indication is the location of the ps2 connectors. So i bought one for 50 EUR + the same amount of shipping. Luckily it had exactly that 486DX2 motherboard, just with an addtional adapter board for the TFT/DSTN display.

Putting it into the SNA, i was a bit disappointed because nothing was happening on screen when the unit was turned on. Measuring voltages showed that the 5V power supply rail measured only 1.8V. Turned out that the old motherboard had blown the fuse in the power supply - replacing that one made a picture appear on the external screen. The internal EL displayed just showed the usual Zebra stripes. I played with the Shadow/Cache settings, but that didn't had any effect. I then noticed a 'Simultaneous Display on both screens' option. I enabled that option, and the EL display showed a picture. Unfortunately only until the next boot, now i cannot get a pictures any more, except the Zebra stripes.

The display also has quite a lot missing lines - not sure what to do about them. I never worked on such displays, maybe it's a driver chip that can be replaced, i just don't know.

The Spectrum Analyzer section seems to be fully working, which is the important part - i put in a 1, 10 and 20GHz signal, and it all looked good.

dxl · « **Reply #80 on:** October 10, 2022, 08:24:22 pm »

ok, the display is definitely not repairable - someone applied way to much force (i have no idea why the metal frame next to the floppy drive is bent - it's hidden inside of the front panel)

manicdoc · « **Reply #81 on:** October 10, 2022, 09:32:40 pm »

use some clear curing epoxy on that damaged area to ensure it won't shatter. aim to fill level with everything else.

Pude · « **Reply #82 on:** October 11, 2022, 05:10:31 am »

I'm also in the process to replace this 35670A screen using RGBtoHDMI and modern screen unit.
I got this HP from Lohja, Finland which is the town where Finlux once made these EL-displays. I wonder if any former employees have some old stock somewhere.

SNA-33 also has Finlux screen originally.

dxl · « **Reply #83 on:** October 11, 2022, 06:52:29 am »

Interesting, didn't knew that HP used the EL screens in the 35670A...

dxl · « **Reply #84 on:** October 11, 2022, 07:05:00 am »

Quote from: manicdoc on October 10, 2022, 09:32:40 pm

use some clear curing epoxy on that damaged area to ensure it won't shatter. aim to fill level with everything else.

The problem is not the mechanical stability, but the electrical "wires" which are on the glass and broken.

dxl · « **Reply #85 on:** October 12, 2022, 05:56:23 pm »

I zipped the firmware of my SNA-33 and uploaded it to ko4bb. It's a revision G model, so different from the H model we already have. I tested whether the H software runs on a G model, and it does.

dxl · « **Reply #86 on:** October 17, 2022, 04:03:37 pm »

One thing that wonders me on my unit is whether the fan is working. The one in the Power supply seems to be working, but the other one next to the mainboard in the back doesn't do anything. I haven't checked the schematics whether that one is temperature controlled or so.

Pude, Gerhard, is that one working on your units?

Qw3rtzuiop · « **Reply #87 on:** October 17, 2022, 04:15:15 pm »

Quote from: dxl on October 17, 2022, 04:03:37 pm

One thing that wonders me on my unit is whether the fan is working. The one in the Power supply seems to be working, but the other one next to the mainboard in the back doesn't do anything. I haven't checked the schematics whether that one is temperature controlled or so.

Its temp controlled. Heat up the marked NTC/PTC(?) and it should start spinning.

dxl · « **Reply #88 on:** October 17, 2022, 05:07:01 pm »

Thanks, the fan is working. I applied some heat and it started spinning. Odd place IMHO given that the power supply has its own fan, and that area doesn't get much airflow from the fan.

dxl · « **Reply #89 on:** October 17, 2022, 07:15:12 pm »

I was wondering why the sweep update rate is slower than on a HP8563E. With the information from the map files i partially reversed the communication protocol between the software and the dsps. It's quite interesting that the sweep only takes 25ms, but the processing between sweep takes almost 75ms. Look at the green and blue cursor lines in the listings, this is one sweep.

I wonder whether this could be improved with a more modern mainboard.

dxl · « **Reply #90 on:** November 22, 2022, 10:15:06 pm »

I "fixed" the display problem on my unit now by replacing the EL screen with a 8.4" 800x600 TFT screen. The firmware needed a few tweaks to recognize the 640x350 video mode, but otherwise it's looking ok. Not as sharp as the EL display because the image gets scaled, but still ok. It also has the nice side effect of adding color. The size of the panel is almost the same as the original one, it's a bit more in height, and about 1cm less in width.

alexturner · « **Reply #91 on:** November 24, 2023, 03:27:59 am »

I had a good year or so with mine working immaculately and today I went to use it and noticed that it's deaf

Not sure where to start looking, I've tried frequencies up to 1GHz (limit of my source), have attached a Log Normal antenna and nothing. Changing attenuators makes no change, any ideas where to start with this? This has been a taxing instrument to own so far

dxl · « **Reply #92 on:** December 05, 2023, 08:14:02 pm »

Can you post a picture of the screen in full span mode? Do you see the normal noise floor?

alexturner · « **Reply #93 on:** December 18, 2023, 10:24:46 pm »

Hey dxl - It sure seems as if it's the normal noise floor in full span. How come?

aseok · « **Reply #94 on:** February 19, 2024, 04:33:38 pm »

Following is picture of sna-20 2101b board, the inductor was blown and removed (white blank part of pcb) also at least some other damaged/blown parts visible. Is there any chance to fix this? is it worth the effort at all?

alexturner · « **Reply #95 on:** February 24, 2024, 05:34:36 am »

Possibly, the schematics are available on the web.

alexturner · « **Reply #96 on:** February 24, 2024, 05:52:49 am »

I spent some time with it and found that the power supply to the YIG oscillator had a bad transistor, swapped and it came back to life. Lasted an entire day, and now it's giving me grief again. When it boots, it displays the preset band fine, then when the unit displays the "Calibration Active" message, the entire signal flies up such that the measurement base is on the 0db line and saturated noise above that.

Does anyone know what "Calibration Active" does in the unit? I've re-loaded my calibration data and checked the internal calibration reference, which is fine. Logarithmizer seems fine too given I see the trace on boot. I've recorded a short video here incase you have any ideas - not sure where to look at this point

https://youtube.com/shorts/tnBPF-xLFNI


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