Author Topic: W&G sna-20/23 spectrum analyzer repair  (Read 19055 times)

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Offline Pude

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Re: W&G sna-20/23 spectrum analyzer repair
« 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.
 

Offline robots

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Re: W&G sna-20/23 spectrum analyzer repair
« 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 :-)
 
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Offline Gerhard_dk4xp

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Re: W&G sna-20/23 spectrum analyzer repair
« 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
« Last Edit: May 10, 2022, 11:32:28 am by Gerhard_dk4xp »
 

Offline Pude

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Re: W&G sna-20/23 spectrum analyzer repair
« 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.
 

Offline Storm

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Re: W&G sna-20/23 spectrum analyzer repair
« 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?
 

Offline Storm

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Re: W&G sna-20/23 spectrum analyzer repair
« 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.
 
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Offline Pude

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Re: W&G sna-20/23 spectrum analyzer repair
« 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!
 

Offline Gerhard_dk4xp

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Re: W&G sna-20/23 spectrum analyzer repair
« 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
 
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Offline Electro4lease

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Re: W&G sna-20/23 spectrum analyzer repair
« 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
 

Offline Pude

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Re: W&G sna-20/23 spectrum analyzer repair
« 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. :)
 

Offline Gerhard_dk4xp

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Re: W&G sna-20/23 spectrum analyzer repair
« 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!

« Last Edit: September 30, 2022, 10:52:34 am by Gerhard_dk4xp »
 

Offline Pude

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Re: W&G sna-20/23 spectrum analyzer repair
« 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. :)
 

Offline dxl

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Re: W&G sna-20/23 spectrum analyzer repair
« 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.
 

Offline dxl

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Re: W&G sna-20/23 spectrum analyzer repair
« 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! :)
« Last Edit: September 30, 2022, 06:38:03 pm by dxl »
 

Offline Pude

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Re: W&G sna-20/23 spectrum analyzer repair / SNA-33
« 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.
 

Offline dxl

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Re: W&G sna-20/23 spectrum analyzer repair / SNA-33
« Reply #65 on: September 30, 2022, 09:06:58 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...
 

Offline Pude

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Re: W&G sna-20/23 spectrum analyzer repair / SNA-33
« Reply #66 on: September 30, 2022, 09:20:20 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?
 

Offline dxl

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Re: W&G sna-20/23 spectrum analyzer repair
« 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.
 

Offline Gerhard_dk4xp

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Re: W&G sna-20/23 spectrum analyzer repair
« 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
 

Offline Pude

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Re: W&G sna-20/23 spectrum analyzer repair / SNA-33
« 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.
« Last Edit: October 01, 2022, 03:46:17 pm by Pude »
 

Offline Gerhard_dk4xp

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Re: W&G sna-20/23 spectrum analyzer repair
« 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.
 
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Offline dxl

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Re: W&G sna-20/23 spectrum analyzer repair / SNA-33
« Reply #71 on: October 01, 2022, 04:05:25 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?
 

Offline dxl

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Re: W&G sna-20/23 spectrum analyzer repair
« 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.
« Last Edit: October 02, 2022, 10:30:03 pm by dxl »
 

Offline dxl

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Re: W&G sna-20/23 spectrum analyzer repair
« 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...
 

Offline Pude

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Re: W&G sna-20/23 spectrum analyzer repair
« Reply #74 on: October 03, 2022, 04:41:12 am »
Here's my unit output from the screen.
 


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