Help fixing Siglent SDG805 (Fixed)

[KaiDT]

@Thomas

Thank you so much!!!! for your generosity. I am now probing every component around U15 as you suggested. Hopefully, everything will be alright. I am about to order U15 ICs but before I do that can I ask you to check if I have got the right Manufacturer Part Number. I am confused as there are 4 part numbers with SOIC type. How can I know which one is the right one? Is this one ok (https://www.digikey.com/product-detail/en/texas-instruments/OPA695IDGKT/296-24333-1-ND/2046693)? 

I will also order R106, R107 and R113 as well as some of them were missing from units that I have sent to supplier for fix T__T.

One more thing, I have checked R105 and it is connected to ground as you said  . (please excuse me for bad soldering skill  )



You guys are so genius. I can only hope that one day I could have vast knowledge as you guys on this form have (It is incredible).

[TurboTom]

KaiDT -

your link points to the wrong casing version, it's a TSSOP which may look correct at the first glance but is much smaller. You need a "Small Outline" (SO) version. The correct TI designation is OPA695ID, Digikey Number 296-16756-5-ND. Digikey lists the correct casing as "8-SOIC". Hope this helps and my reply isn't too late...

Cheers,
Thomas

P.S. I wouldn't touch R113 since it's a comparably high resistance (499R) that wouldn't get damaged that easily by a (lowish) voltage applied from the output. Just measure it in-circuit while R107 is out for replacement, and if it appears correct, leave it there. Btw, your last photo shows clearly that R106 / R107 are NOT part of the feedback loop of U115 (as I previously thought they were) -- this is a clear indication that U115 is really the culprit. Due to the presence of the (apparently fully functional) clamping diode, R113 cannot be damaged. Someone has probably supplied a voltage (12VDC??) from a PSU into the output of the generator that has been configured for a low output amplitude (<= 5Vpp) with the output enabled. Just to be sure, I'ld replace D3 (BAV99) anyway.

[KaiDT]

KaiDT -

your link points to the wrong casing version, it's a TSSOP which may look correct at the first glance but is much smaller. You need a "Small Outline" (SO) version. The correct TI designation is OPA695ID, Digikey Number 296-16756-5-ND. Digikey lists the correct casing as "8-SOIC". Hope this helps and my reply isn't too late...

Cheers,
Thomas

You have come to my rescue again Thomas. Thank you so much!! As I am very bad regarding to smd standard (you can see that I know it should be SOIC. I still pick the wrong part T__T), I am patiently waiting for your reply prior to placing the order. I just cannot thank you enough. Once I have all the parts, I will update you guys again. Finger crossed!!

Someone has probably supplied a voltage (12VDC??) from a PSU into the output of the generator that has been configured for a low output amplitude (<= 5Vpp) with the output enabled.

These function generators have been used by students who love to just keep the output enabled while doing their experiment. I have seen the students unknowingly short the output by shorting two output cables together through the circuit!!! and all kind of crazy stuff. I am not really surprised the units keep failing every year T__T.

[TurboTom]

Maybe you can do the repair job together with your students (regardless if they messed the thing up or not), explain what, how and why it happened and I'm sure they will learn a lot and the chance of them doing this same mistake (again) will be reduced for sure.

[KaiDT]

Maybe you can do the repair job together with your students (regardless if they messed the thing up or not), explain what, how and why it happened and I'm sure they will learn a lot and the chance of them doing this same mistake (again) will be reduced for sure.

Thanks for your suggestion ^^. It is such a good idea. I will certainly do it next time. I am just not sure I would be such a good person in explaining it  as I am still struggling to under how circuit works. However, thanks to you I know how to troubleshoot it now  .

[KaiDT]

Quick updates on my problems.

Just got OPA695 and have them replaced on the 3 bad units. All 3 units now function properly yay!! .

Millions Thanks to tautech and rf-loop with information on output opamps on the old thread and specially Thomas for guiding to the faulty components. My boss is a happy man like now that he did not have to buy replacement units ^^.

There is still though one unit (boot freeze problem) left to fix. I have found this blog http://41j.com/blog/2016/08/hacking-around-with-a-sdg800-sdg805/ and discovered that he is also a forum member at EEVblog forum. I have already Pm him asking for advice so maybe with his help I can get this unit to boot so I can update its firmware to the latest. Finger crossed ^^.

[tautech]

OK, good, just one left to fix.

PM received from KaiDT

[rf-loop]

There is still though one unit (boot freeze problem) left to fix. I have found this blog http://41j.com/blog/2016/08/hacking-around-with-a-sdg800-sdg805/ and discovered that he is also a forum member at EEVblog forum. I have already Pm him asking for advice so maybe with his help I can get this unit to boot so I can update its firmware to the latest. Finger crossed ^^.

About boot freeze unit.

If boot stop to phase when it just show Siglent logo ok and after then boot up process do not go forward, it is possible to try recover using Siglent official method aka SD card recovery for SDG800. Least it need try before any other methods (other methods may in worst case destroy this possibility).

It need some tiny hardware rework, load system recovery FW file from SD card (SD card slot is there on main board) and after then return hardware back to original state and after it works ok then update to latest FW normal way.

As far as I know this method instructions and system recovery files are not in public share but they are available. This method is bit critical and need do carefully and exactly as instructions show without any single exception including also order of actions and including given tool for formatting SD card. I recommend you try this Siglent official SD recovery method, instead of some wild experiments that are presented here and there.

You can get instructions and recovery files package (.ZIP)  from Siglent technical support but it need understand and promise they are confidential.  If you have troubles to get this, don't give up, I believe there are other ways to get it.  Only if this method fails, then you can use some other things and experiments you may find around.

[tautech]

@rf-loop
The boot freeze unit is now recovered from advise I offered. 

[KaiDT]

There is still though one unit (boot freeze problem) left to fix. I have found this blog http://41j.com/blog/2016/08/hacking-around-with-a-sdg800-sdg805/ and discovered that he is also a forum member at EEVblog forum. I have already Pm him asking for advice so maybe with his help I can get this unit to boot so I can update its firmware to the latest. Finger crossed ^^.

About boot freeze unit.

If boot stop to phase when it just show Siglent logo ok and after then boot up process do not go forward, it is possible to try recover using Siglent official method aka SD card recovery for SDG800. Least it need try before any other methods (other methods may in worst case destroy this possibility).

It need some tiny hardware rework, load system recovery FW file from SD card and after then return hardware back to original state and after it works ok then update to latest FW normal way.

As far as I know this method instructions and system recovery files are not in public share but they are available. This method is bit critical and need do carefully and exactly as instructions show without any single exception including also order of actions. I recommend you try this Siglent official SD recovery method, instead of some wild experiments that are presented here and there.

You can get instructions and recovery files package (.ZIP)  from Siglent technical support but it need understand and promise they are confidential.  If you have troubles to get this, don't give up, I believe there are other ways to get it.  Only if this method fails, then you can use some other things and experiments you may find around.

@rf-loop

Thanks for your information. As you have suggested, the boot freeze unit is now recovered with advice from tautech. All faulty units now have been functioning again. I would not have been able to do it without you guys and all information you shared with me. I am so grateful for all your helps.

Edited: ^^ tautech, you beat me to it ^^

[rf-loop]

There is still though one unit (boot freeze problem) left to fix. I have found this blog http://41j.com/blog/2016/08/hacking-around-with-a-sdg800-sdg805/ and discovered that he is also a forum member at EEVblog forum. I have already Pm him asking for advice so maybe with his help I can get this unit to boot so I can update its firmware to the latest. Finger crossed ^^.

About boot freeze unit.

If boot stop to phase when it just show Siglent logo ok and after then boot up process do not go forward, it is possible to try recover using Siglent official method aka SD card recovery for SDG800. Least it need try before any other methods (other methods may in worst case destroy this possibility).

It need some tiny hardware rework, load system recovery FW file from SD card and after then return hardware back to original state and after it works ok then update to latest FW normal way.

As far as I know this method instructions and system recovery files are not in public share but they are available. This method is bit critical and need do carefully and exactly as instructions show without any single exception including also order of actions. I recommend you try this Siglent official SD recovery method, instead of some wild experiments that are presented here and there.

You can get instructions and recovery files package (.ZIP)  from Siglent technical support but it need understand and promise they are confidential.  If you have troubles to get this, don't give up, I believe there are other ways to get it.  Only if this method fails, then you can use some other things and experiments you may find around.

@rf-loop

Thanks for your information. As you have suggested, the boot freeze unit is now recovered with advice from tautech. All faulty units now have been functioning again. I would not have been able to do it without you guys and all information you shared with me. I am so grateful for all your helps.

Edited: ^^ tautech, you beat me to it ^^

Nice to hear. Good!

[tautech]

Thanks for your information. As you have suggested, the boot freeze unit is now recovered with advice from tautech. All faulty units now have been functioning again. I would not have been able to do it without you guys and all information you shared with me. I am so grateful for all your helps.

You're welcome and we also should not forget help from TurboTom.

Still, you did all the work and got a good result. 
Enjoy. 

[PlasmaArcEng]

I though this was a similar enough problem to post here.  I have a brand new SDG810 unit I unboxed yesterday (purchased years ago for a project) and it froze on boot up at the "Kernel Starting" screen. I did notice that after about 10 seconds there was a glitch on the screen and the internal piezo made a click. This made me think it was the early firmware/software problem.
I have tried the USB restore and it didn't work. I then tried the SD card restore and that unfortunately has made the screen not display anything. During the SD card restore it took 2 seconds after the lights turned on for the screen to come up with the same "Kernel Starting" screen and I left if for 10 minutes before turning it off and tried reformatting and reloading the SD card. This time the screen stayed black with the buttons illuminated with the internal piezo making a clicking noise every 3 seconds. I then re-soldered the resistors to the original configuration and the screen stayed black when I powered it up again.
All regulated power rails seem to OK at the test points.
Any help would be appreciated.

[tautech]

I though this was a similar enough problem to post here.  I have a brand new SDG810 unit I unboxed yesterday (purchased years ago for a project) and it froze on boot up at the "Kernel Starting" screen. I did notice that after about 10 seconds there was a glitch on the screen and the internal piezo made a click. This made me think it was the early firmware/software problem.
I have tried the USB restore and it didn't work. I then tried the SD card restore and that unfortunately has made the screen not display anything. During the SD card restore it took 2 seconds after the lights turned on for the screen to come up with the same "Kernel Starting" screen and I left if for 10 minutes before turning it off and tried reformatting and reloading the SD card. This time the screen stayed black with the buttons illuminated with the internal piezo making a clicking noise every 3 seconds. I then re-soldered the resistors to the original configuration and the screen stayed black when I powered it up again.
All regulated power rails seem to OK at the test points.
Any help would be appreciated.

Welcome to the forum.

Another PM sent following those sent yesterday.