Siglent SSG3000X and SSG5000X series RF Signal generators

[Martin72]

My dear Rob, I'm just a little fool.
Not a big one.
But I can't see very well, the matter of whether or not there is an IQE module is clarified very quickly without measuring weight.

[Nokia6681]

Hello from Germany,

I have a question for you, I have the Siglent SSG3021X which no longer has an output as of today, I had not previously set up a device with it and then suddenly the output was DEAD, at the absolute output maximum there was still a low signal level but no signal full power more.

Now the question is what could be defective here, with a circuit diagram I would certainly be able to determine it straight away, but where can I get something like that from?

Do any of you have a circuit diagram of the HF output?

[tautech]

Hello from Germany,

I have a question for you, I have the Siglent SSG3021X which no longer has an output as of today, I had not previously set up a device with it and then suddenly the output was DEAD, at the absolute output maximum there was still a low signal level but no signal full power more.

Now the question is what could be defective here, with a circuit diagram I would certainly be able to determine it straight away, but where can I get something like that from?

Do any of you have a circuit diagram of the HF output?

First Preset then adjust Level and Frequency to values you can easily test.
Have you checked the BNC LF output is working correctly ?
Then work through the SM checks:
https://int.siglent.com/u_file/download/19_11_22/b8cd0afabb.pdf

[Nokia6681]

I never use the LF output.
 a check using the service instructions does not reveal any errors. I think that the device that I previously compared may have sent and destroyed the output Amp.
Unfortunately, Siglent only specifies a maximum DC input voltage at the output but does not indicate the maximum amount of HF that can enter the output. I haven't disassembled it yet to get a closer look at the components used.

[tautech]

I never use the LF output.
 a check using the service instructions does not reveal any errors. I think that the device that I previously compared may have sent and destroyed the output Amp.
Unfortunately, Siglent only specifies a maximum DC input voltage at the output but does not indicate the maximum amount of HF that can enter the output. I haven't disassembled it yet to get a closer look at the components used.

Yet it is a check the rest of the generator is working correctly and any damage is confined to HF RF output.

Not heard of damage/failures in these before so do keep us posted with your findings.

[Nokia6681]

I'm going to carry out more tests today, especially regarding the LF output, but I think I destroyed it with the radio, it's quite possible that I was transmitting with it and forgot to put it back on the dummy load and the generator was damaged as a result .

My dealer said 4 years ago that nothing is normally repaired on this device but that it is either repaired or replaced at a flat rate, but spending over 1000 euros on it makes me reluctant to look for a circuit diagram, but I will do it this afternoon as soon as I can I have time to disassemble and see what generates the output here, the driver stage must still be working because with the full output power setting, around 10-20µV still comes out of the output.

[tautech]

I'm going to carry out more tests today, especially regarding the LF output, but I think I destroyed it with the radio, it's quite possible that I was transmitting with it and forgot to put it back on the dummy load and the generator was damaged as a result .

My dealer said 4 years ago that nothing is normally repaired on this device but that it is either repaired or replaced at a flat rate, but spending over 1000 euros on it makes me reluctant to look for a circuit diagram, but I will do it this afternoon as soon as I can I have time to disassemble and see what generates the output here, the driver stage must still be working because with the full output power setting, around 10-20µV still comes out of the output.

I'm 100% sure many could benefit from your findings and any imagery of PCB and devices.
Best of luck.

[Nokia6681]

YES i will do my best, Pictures i will Record some of this , i hope sharp !

[TurboTom]

Reverse power events are the usual culprits of such failures in RF signal generators.  Even though virtually all these instruments have some reverse power protection at their outputs, if you happen to supply "enough" power in reverse, these measures either aren't fast enough or just won't be able to cope with the amount of power (some single-digit wattage will most probably be tolerated for a short time, but if it's in the 100W ballpark, it's "Hasta la vista, Baby").

These defects can be repaired in most cases since they are usually very localized, but it's questionable if the instrument is still in spec after the repair and even more so if you will be able to get a schematic. Higher reverse power events also may charr some components and even damage the PCB. I was lucky that two repairs of R&S SM300s with similar problems turned out okay for me (also no schematics, but at least a decent block diagram available). I think the Siglent generator will be easier to repair simply due to the more "organized" mechanical construction. But you will definitely need some experience and RF technology knowledge, and identifying components may be somewhat awkward as well.

Depending on your own experience, it may ba a good idea to disassemble the instrument and post some good, detailed photos of the relevant section here for supportive opinions before starting to actually "rework" the instrument.

Good luck with the repair and all the best,
Thomas

[Nokia6681]

Today I removed the mainboard and checked, R620 (49.9R) burned out, but the U70 is still supplied with 3.3V voltage, U46 should get voltage via C755, as does U45 via C754, at least I did with U45 There is voltage on both pins of C754, and all other components that look like this are apparently suppression chokes + C
U70 is the same chip as the Siglent SSA 3021 digital attenuator.
The LF output works perfectly, I have now ordered the H1118.
I was also able to measure the HF at full power up to U39, but after that the HF continues to decrease, but it could be that the U70 is blocking the data due to the 30W that went into it and now other ICs can't switch properly here.

I have to put all the pictures on my server because I can only post 2 pictures in full resolution here

[Nokia6681]

Here is the Link to my Server Folder with more Pictures uncompressed !

https://www.asz-muenchen.de/reserve/Siglent/

[Nokia6681]

In Germany if you need spare parts there is absolutely nothing left, you can't even get the 49.9 ohm resistor anywhere, these days you have to order everything from somewhere abroad, it's a shame and you then wait for these parts for weeks, It's no fun anymore to repair any device. Just buy and use everything and throw it in the electronic waste.

Is that also the case in your countries? Or can you get parts better here, Mauser Elektronik has pretty much no idea where they get these parts from, but you don't really want to order everything for 20 euros or so much that you don't need in order to save on shipping do it.

Have you looked at the pictures, a super clean layout, but beware of something broken like mine is currently, then good advice is very expensive.

[TurboTom]

My approach for initial fault finding would be to remove U70 (Hittite / Analog H1118) and to jumper pads 14 and 3 on the pcb with a wire as short as possible. If the output signal is re-established at the proper level, replace U70 and you should be ready to go.

The tricky part will be removal of U70 since it's got an exposed pad, the board appears to be at least a hybrid composition, maybe Rogers, and the "white" (RF) side of it isn't typically known for its rigidity... Traces are easily pulled off if the solder isn't completely liquefied. Lead-free solder that Siglent used for assembly doesn't simplify things either. You need a decent SMT rework setup and some experience to get it right. At least, I wouldn't approach the job with single-sided heating of the PCB, due to the multiple layers of copper inside.

I hope that the "dump switch" U70 has saved the rest of the circuitry!

All the best,
Thomas