Siglent SDS2000X Plus

[bdunham7]

I read this. However, I can not power recycle the unit. Nothing happens when I press power button.

Do you have a way of accurately measuring the power or current going into the unit?  I used a Kill-A-Watt.  When plugged in, the standby power supply should use 2 to 3 watts or about 30-40mA of current, maybe a bit less if your mains voltage is higher.  There will be a brief surge of about twice that just as you plug it in.  If you can, see if you have that current draw.  If not, then you know where to start.  If you do have the draw, then perhaps start with the switch itself or the wires to it.

[bdunham7]

Disconnect ALL cables. Wait 5 minutes. Connect only power cable. Then power on and do the MATH button thing even if you don't see a logo popup.

Right as you press the button there should be a click and the power button should light up.  IDK for sure, but I would think that part doesn't depend on the system booting up or even starting to, I think that is all PSU hardware behavior.

[ozkarah]

I read this. However, I can not power recycle the unit. Nothing happens when I press power button.

Try this:

Disconnect ALL cables. Wait 5 minutes. Connect only power cable. Then power on and do the MATH button thing even if you don't see a logo popup.

You might need recovery files, which might help your situation if the above doesn't help.

Didn't help. Nothing happens with the power button.
I guess it is power supply unit.

[ozkarah]

I read this. However, I can not power recycle the unit. Nothing happens when I press power button.

Do you have a way of accurately measuring the power or current going into the unit?  I used a Kill-A-Watt.  When plugged in, the standby power supply should use 2 to 3 watts or about 30-40mA of current, maybe a bit less if your mains voltage is higher.  There will be a brief surge of about twice that just as you plug it in.  If you can, see if you have that current draw.  If not, then you know where to start.  If you do have the draw, then perhaps start with the switch itself or the wires to it.

Good idea. Not at the moment I have the tools to do it.
But, tomorrow I will try to do and inform.
 

[tautech]

I read this. However, I can not power recycle the unit. Nothing happens when I press power button.

Try this:

Disconnect ALL cables. Wait 5 minutes. Connect only power cable. Then power on and do the MATH button thing even if you don't see a logo popup.

You might need recovery files, which might help your situation if the above doesn't help.

Didn't help. Nothing happens with the power button.
I guess it is power supply unit.

Or a faulty lead.
Recently had a random IEC lead go open circuit which got the sidecutter treatment and into the bin ! 

No it wasn't one supplied by Siglent. 

[KungFuJosh]

Yeah, it sounds like you need to check the IEC socket...and double check the power fuse. 😉

[Martin72]

Hi,

If you have checked the power cable, the mains input and the fuse below, you will not be able to avoid an opening.
Unplug the plug from the output of the internal power supply unit on the mainboard, then reconnect the power cable and measure the output plug to see if there is any voltage present.

[ozkarah]

Or a faulty lead.
Recently had a random IEC lead go open circuit which got the sidecutter treatment and into the bin ! 

No it wasn't one supplied by Siglent. 

The lead should be okay. SSA3021X Plus runs perfectly on this lead.

[ozkarah]

Hi,

If you have checked the power cable, the mains input and the fuse below, you will not be able to avoid an opening.
Unplug the plug from the output of the internal power supply unit on the mainboard, then reconnect the power cable and measure the output plug to see if there is any voltage present.

Thanks Martin, yes, it seems to be inevitable

[ozkarah]

Today, problem persists. I opened the scope and checked the power supply.
There is no voltage any of power supply output pins.

- NTC at the mains input is okay.
- Mains voltage comes till the rectifier bridge (filter is okay).
- Fuses and diodes at the back side of the board are okay.
- There are two optocouplers (one is near the flyback and not seen in the picture).  Input LEDs of both are recognized as diodes, so I assume, the input side of optocouplers should be okay.

I didn't make any further investigation yet. I will continue on Thursday.

Any suggestions?

 @tautech: is power supply board sold separately? (marking is: SDY8.007.129G)

[tautech]

Today, problem persists. I opened the scope and checked the power supply.
There is no voltage any of power supply output pins.

- NTC at the mains input is okay.
- Mains voltage comes till the rectifier bridge (filter is okay).
- Fuses and diodes at the back side of the board are okay.
- There are two optocouplers (one is near the flyback and not seen in the picture).  Input LEDs of both are recognized as diodes, so I assume, the input side of optocouplers should be okay.

I didn't make any further investigation yet. I will continue on Thursday.

Any suggestions?

 @tautech: is power supply board sold separately? (marking is: SDY8.007.129G)

Yes, it's a common PSU to several Siglent products.

From my Siglent PSU list it's: SDS2000X Plus   Pt# 1.20.00.00.029R

[pasha]

may be there is an external trigger pin to run it, like in computer power supplies,
may be waiting in standby mode until it is triggered.

[bdunham7]

I don't see any PFC circuitry nor standby power circuits or any way to signal the PSU to turn on or off.  So, along with the excerpt from the service manual provided by Martin72, I guess we can conclude that the PSU is always fully on when plugged in.  I'm not sure that's what I expected....

I guess the next step would be to price out a PSU just in case it is reasonably cheap and convenient to obtain.   As far as fixing the board, are there markings visible on the 3 ICs between the large transformer and the capacitors or are they sanded off?  Also, is the AC trigger signal present on pin 7?

[tautech]

I guess the next step would be to price out a PSU just in case it is reasonably cheap and convenient to obtain.   As far as fixing the board, are there markings visible on the 3 ICs between the large transformer and the capacitors or are they sanded off?  Also, is the AC trigger signal present on pin 7?

Never seen buffed IC's on Siglent PSU's. 

Line trigger signal in the 2kX Plus is provided from another small PCB using a Opto for isolation.

[bdunham7]

Line trigger signal in the 2kX Plus is provided from another small PCB using a Opto for isolation.

The service manual says that AC line trigger is on pin 7 of this PSU and there's a separate 4-pin opto next to the transformer (you can see it from the backside view in his photos).  Is that not the way it actually is?  IDK why they'd need two optos otherwise.  In any case, is the PSU reasonably available as a service part? 

[bdunham7]

Any suggestions?

Post some clear, detailed photos showing the markings on all the ICs.  If you can't get them to show up on a photo, note down the part numbers of each one.

If this type of SMPS is not starting at all, it is likely due to some failure to the north of the large transformer.  Try to get part numbers or values for every component possible in that area on both sides of the board.  First look at the 16-pin IC just above the input reservoir capacitor.

[Martin72]

may be there is an external trigger pin to run it, like in computer power supplies,
may be waiting in standby mode until it is triggered.

The power supply starts up as soon as it has input voltage - the secret of Siglent's high standby consumption.
The SDS2k+ has no extra board for the mains trigger, the mains cables go directly into the power supply.
I would check with Siglent EU HQ how much the power supply costs; if it is well under €100, repairing/troubleshooting the old power supply would be of purely academic interest.

[bdunham7]

The SDS2k+ has no extra board for the mains trigger, the mains cables go directly into the power supply.

The OnSemi 4N35 is set up to send an AC signal across to the low voltage side.  Whether they've biased it to send a clean AC sine or just hacked off version, IDK.  The feedback opto for voltage regulation is up next to the transformer.

[ozkarah]

Post some clear, detailed photos showing the markings on all the ICs.  If you can't get them to show up on a photo, note down the part numbers of each one.

If this type of SMPS is not starting at all, it is likely due to some failure to the north of the large transformer.  Try to get part numbers or values for every component possible in that area on both sides of the board.  First look at the 16-pin IC just above the input reservoir capacitor.

All ICs are readable. I will post some more pictures tomorrow.

The power supply starts up as soon as it has input voltage - the secret of Siglent's high standby consumption.
The SDS2k+ has no extra board for the mains trigger, the mains cables go directly into the power supply.
I would check with Siglent EU HQ how much the power supply costs; if it is well under €100, repairing/troubleshooting the old power supply would be of purely academic interest.

I agree Martin. I will contact the local Siglent distributors tomorrow. Let's hope they offer a reasonable price.

@tautech, do you have a clue about the price of PSU in your zone?

[bte]

I would check with Siglent EU HQ how much the power supply costs; if it is well under €100, repairing/troubleshooting the old power supply would be of purely academic interest.

If Siglent EU HQ can send the part to the distributors here, then what you suggest could be viable. In Turkey we are limited to a personal import limit of 30 EUR including shipping, so it's either the part can be obtained through the distributor or someone coming from abroad will bring the part. Otherwise it's repair time.

[Just a few notes about the situation here: Above 30 EUR it becomes a commercial item and you are required to file it with the ministry. You as a person can't do it so you must use the services of brokers. What hurdles can the customs throw at you when it is a commercial item is anyone's guess. They could for example ask to have it "certified" by the national standards which could mean you could choose to buy another scope instead of trying to import that part.

Even if the item value is below 30 EUR, the customs may consider it commercial and give you a headache. For example, you order 5 small PCBs from a PCB house in China for $10 and pay $5 shipping. You think all is well because the total value is below 30 EUR but here's the kick: the customs will declare the item as commercial since there are 5 pieces. So instead of paying the fixed 60% tax and having your PCBs, you will be given a runaround and an exorbitant bill to pay at the end.

If you don't pay, item will be considered abandoned and will be auctioned off to be sold to the "merchants" whose business is selling such auctioned items. So, the item that once needed to be "certified" can easily be sold within the country after it goes through the "official" channels. It's entirely possible that you can find your confiscated/abandoned item and purchase it if you somehow can come across it via i.e. a google search.]

[tautech]

The SDS2k+ has no extra board for the mains trigger, the mains cables go directly into the power supply.

The OnSemi 4N35 is set up to send an AC signal across to the low voltage side. Whether they've biased it to send a clean AC sine or just hacked off version, IDK.  The feedback opto for voltage regulation is up next to the transformer.

Yeah sorry, you are entirely correct.
Just checked a PSU here and the opto is connected after the mains input filtering just before the bridge rectifier.
So clean sinewave....well as clean as mains can be......

@tautech, do you have a clue about the price of PSU in your zone?

Sorry no, we don't have a PSU pricelist.
They get charged to distributors at cost for us to decide how much to mark them up. 

If you brought it from me I'll treat you well.......sorta stuff. 


PS, it will be more than 30 Euro.

[tautech]

Any suggestions?

Post some clear, detailed photos showing the markings on all the ICs.  If you can't get them to show up on a photo, note down the part numbers of each one.

If this type of SMPS is not starting at all, it is likely due to some failure to the north of the large transformer.  Try to get part numbers or values for every component possible in that area on both sides of the board.  First look at the 16-pin IC just above the input reservoir capacitor.

Not your ordinary SMPS controller but a High-voltage resonant controller.
Datasheet attached.

[ozkarah]

I have some updates.

We made further tests and one of the MOSFETs marked in the first picture is shorted.
The original MOSFETs are FQPF9N50C. However, it was not possible to find a seller here. Thus, among the items I could find in stock,  I ordered an alternative with better specs: P15F60HP2F-5600

Also ordered the  SMPS controller IC (mentioned by tautech - marked in picture 2)  (L6599AD - IC-6599 RESONANT CONVERTER CONTROLLER 16SOIC), in case it is also broken.

When the parts arrive, I will replace them and inform.
Fingers crossed...

 

[tautech]

I have some updates.

We made further tests and one of the MOSFETs marked in the first picture is shorted.
The original MOSFETs are FQPF9N50C. However, it was not possible to find a seller here. Thus, among the items I could find in stock,  I ordered an alternative with better specs: P15F60HP2F-5600

Also ordered the  SMPS controller IC (mentioned by tautech - marked in picture 2)  (L6599AD - IC-6599 RESONANT CONVERTER CONTROLLER 16SOIC), in case it is also broken.

When the parts arrive, I will replace them and inform.
Fingers crossed...

So so often SMPS controller implementation mimics Typical application schematics in their datasheets.
The actives are most likely to fail but don't discount a passive failing, such as the resistor droppers from HV DC to the controller's Vcc.
Not saying that is the case here but keep your eyes open and proceed with an open mind. 

Looking forward to your findings..... 

[bte]

The original MOSFETs are FQPF9N50C. However, it was not possible to find a seller here.

A quick search for FQPF9N50C returned results that indicate the item is obsolete but a few retailers in Turkey, some of them reporting number of items in stock, claim to have the item. Just out of curiosity since I didn't do business with any of them: Did you contact them to find out that they actually didn't have any stock?

Few examples from what I could find:

https://karakoyelektronik.com/transistor/fqpf9n50c-23318
https://www.ulutaselektronik.com/urun/fqpf9n50c-to-220f-9a-500v-44w-0-8-n-channel-mosfet
https://fevaris.com/mosfet/fqpf9n50c-n-kanal-9a-500v-to-220f-mosfet-transistor