Siglent spd3303x-e reboot problem

[qpit3a]

About a week ago my spd3303x-e started to get the problem where it re-boots (every 5 minutes or so - in the garage just before where it was very cold I think maybe 15 minutes.  I looked on the forum and found that one suspect is the overheating bridge rectifier.  I looked inside tonight and see that my device must be an updated unit as there's a heatsink on the bridge.  I started measuring some temperaturs and the bridge gets to about 30 but there's a couple of diodes that get to 40.  (measuring with a fairly cheap infra-red thermometer so not sure how accurate). My question is has anyone found that these diodes overheat and cause the same issue?  Is 30 - 40 degrees C too hot?  Just looked at datasheet for 1a diodes and this is not hot.  Then again the cool parts of the board were about 10 degrees C.

Yeah I just checked and these temperatures aren't high.  Will need to check in another way as I don't trust how I measured.  Wondering if anyone else has found a cause for this re-boot problem.           

I think I may have found an answer https://www.youtube.com/watch?v=2uhE6i6VGSs.  Apparently another person has a unit with the new heatsink and still gets the issue as I am.

Thanks for any help

[qpit3a]

Ok yeah if I put small fan on the area where the bridge rectifier is then no reboot so the issue is in the part of the board. It's also when the outputs are on as then that part is powering some relay coils. As per YouTube video I linked.

[qpit3a]

There Siglent, fixed it for you (I hope)...

[tautech]

There Siglent, fixed it for you

Sorry late to the party and yes that will fix it. 

I've only seen the one do this continual reboot, a unit just a few days old that we immediately replaced.
It's the small circular diode bridge failure < replace it = fixed.
For years they used these little circular bridges and seem to not have given any trouble until recently however now I believe a HW mod has upgraded to a better bridge from one of these little critters.



Liking the chunky replacement you did. 

Others that find this, within 3 years of purchase it's a warranty issue.

[qpit3a]

I gave up on the warranty - the Australian distributor I bought from weren't interested in me I think - not a corporate customer.  In any case I had the bits on hand so easy to fix.  Am a little worried that the caps have cooked a bit and they're going to have reduced life.  Was going to  use a 25 Amp bridge but ddidn't think it would fit... Sort of like that's not a bridge this is a bridge...

[qpit3a]

Also mine had a heatsink on same tiny bridge so if that's the new fix then doesn't work too well after about 2 yrs light use.

[tautech]

Also mine had a heatsink on same tiny bridge so if that's the new fix then doesn't work too well after about 2 yrs light use.

Not seen any with heatsinks however replacement bridges Siglent sent us and a warranty replacement PCB are of an inline bridge design with a higher current bridge.
The failure we had, one diode in the bridge had gone open and the resultant ripple set the unit into constant reboot mode.

Maybe Siglent used a different circular bridge than original for whatever reason and it's just not up to the task.

[qpit3a]

Ok thanks didn't check the old bridge so will be interesting to see if same open diode issue.

[Faranight]

Damn! Looks like I got a free ticket to join this club as I've just been hit with the very same issue.
I was trying to do some AVR programming while the unit suddenly rebooted a few times and then started turning off and back on again.
I've had my SPD3303X for a few years, but used it very rarely. Searching on the internet, it seems to be a known problem.

Tautech, I heard you mentioning in another thread that Siglent started replacing these bridges with more powerful versions that are placed off-board.
Do you perhaps have the part number? Or qpit3a, do you have a part number of that bridge you showed in the pics?

Thanks.

[tautech]

Damn! Looks like I got a free ticket to join this club as I've just been hit with the very same issue.
I was trying to do some AVR programming while the unit suddenly rebooted a few times and then started turning off and back on again.
I've had my SPD3303X for a few years, but used it very rarely. Searching on the internet, it seems to be a known problem.

Tautech, I heard you mentioning in another thread that Siglent started replacing these bridges with more powerful versions that are placed off-board.

Only member qpit3a's fix is the only one I know of that is done off the PCB.

Siglents suggested fix is a bodge by having an inline bridge shoehorned into a circular bridge footprint.
I suspect they reworked the PCB in later HW revisions to take an inline bridge as there's not much room to work with in the older PCB layout.

TBH I'd make a small birds nest with 4 diodes and run a sleeved + and - back into the existing pads or go with qpit3a's fix with a remotely mounted bridge or maybe try to get one of these little 3A jobbies slotted into the existing footprint:
https://www.retroamplis.com/BR305/en

The application is not very demanding as I believe the original bridge was only 2A rated.

[qpit3a]

The original bridge is a 2W10 - 2A.  My new bridge is something I had around and is BR106 10Amp.
The original 2W10 failed even with a  (tiny, and from factory) heatsink in my case.  I also tried a small fan on that part of the board and that did fix the issue, but I didn't like that solution.

[Faranight]

Thanks for the info.

I wonder... I've been googling this issue now, and I came across this video on Youtube where the guy does the diode bridge repair, but also includes certain 78xx linear regulators in the fix. He says that those were also getting too hot, so he decides to replace them with bigger ones (78L05 TO-92 with 7805 TO-220) and move some of them off-board to mount them on the chassis for better cooling. I found some IR shots of the PCB with the diode bridge overheating in this thread, but I couldn't find any similar pictures for the said regulators. Do you have any info on this i.e. do the regulators really need replacing too?

[qpit3a]

I don't know about the regulators, pretty sure finger checked temps and seemed ok. I didn't find above video although I've seen another where put bridge out on long legs. This guy replaced capacitors which I am thinking I should have done. In this same video there is an analysis suggesting main current draw is to the output relays and is after bridge but before the regulators - I was trusting this analysis (except I should have been less impatient perhaps and got some new caps).

I made video too but didn't film much of the actual process of doing the repair. Just showed checking that problem is heat in that area with the fan and final result. I ran the PSU all night after and was ok and has been good since. Don't have flir so can't properly check temps. Used a infra red thermometer but that didn't show any temps more than ~40.. so I am suspicious wasn't getting good readings.

[Faranight]

Hey, I know it's been a while, but here's my fix. Seems to be working fine without any reboots, and the new bridge barely gets hot.
Although, the two linear regulators near the removed bridge still get pretty hot. Maybe I should have placed them off-board too?

[mawyatt]

Damn! Looks like I got a free ticket to join this club as I've just been hit with the very same issue.
I was trying to do some AVR programming while the unit suddenly rebooted a few times and then started turning off and back on again.
I've had my SPD3303X for a few years, but used it very rarely. Searching on the internet, it seems to be a known problem.

Tautech, I heard you mentioning in another thread that Siglent started replacing these bridges with more powerful versions that are placed off-board.

Only member qpit3a's fix is the only one I know of that is done off the PCB.

Siglents suggested fix is a bodge by having an inline bridge shoehorned into a circular bridge footprint.
I suspect they reworked the PCB in later HW revisions to take an inline bridge as there's not much room to work with in the older PCB layout.

TBH I'd make a small birds nest with 4 diodes and run a sleeved + and - back into the existing pads or go with qpit3a's fix with a remotely mounted bridge or maybe try to get one of these little 3A jobbies slotted into the existing footprint:
https://www.retroamplis.com/BR305/en

The application is not very demanding as I believe the original bridge was only 2A rated.

Rob,

Did Siglent ever have an official "fix" for this? One of our 3 units just began to hiccup a bit, and considering fixing it before we have to use it again.

Best

[tautech]

Damn! Looks like I got a free ticket to join this club as I've just been hit with the very same issue.
I was trying to do some AVR programming while the unit suddenly rebooted a few times and then started turning off and back on again.
I've had my SPD3303X for a few years, but used it very rarely. Searching on the internet, it seems to be a known problem.

Tautech, I heard you mentioning in another thread that Siglent started replacing these bridges with more powerful versions that are placed off-board.

Only member qpit3a's fix is the only one I know of that is done off the PCB.

Siglents suggested fix is a bodge by having an inline bridge shoehorned into a circular bridge footprint.
I suspect they reworked the PCB in later HW revisions to take an inline bridge as there's not much room to work with in the older PCB layout.

TBH I'd make a small birds nest with 4 diodes and run a sleeved + and - back into the existing pads or go with qpit3a's fix with a remotely mounted bridge or maybe try to get one of these little 3A jobbies slotted into the existing footprint:
https://www.retroamplis.com/BR305/en

The application is not very demanding as I believe the original bridge was only 2A rated.

Rob,

Did Siglent ever have an official "fix" for this? One of our 3 units just began to hiccup a bit, and considering fixing it before we have to use it again.

Best

There is warranty. 

They are not a complex/difficult repair but IMO qpit3a's fix above with an uprated bridge is the easiest if replacing the small circular bridge. Run a red/black pair and an AC pair off the PCB and mount the replacement bridge wherever is most convenient.

There has been a HW change however exactly what has been changed has not been shared. 

No doubt the bridge has been uprated/changed so to be more reliable and another display feature has been added; a totalizer readout when in Parallel and Series modes. 
Unfortunately the latest FW that supports this is not compatible with earlier HW. 

Somewhere IIRC I have a rework doc which when found I'll shoot it to your email.

[tautech]

A warranty repair just done...installed the new version control PCB with uprated bridge rectifier.

[MathWizard]

My 3303 must be over 3yrs old by now. I had it open already tho. Do these have a fan though ? I can't remember seeing one or ever hearing 1. I hardly ever use much power, so IDK.

But thanks I'll remember to check the rectifier next time I open it up. I bet it's due for a de-dusting too.

I have some quiet computer fans, that would use under 100mA at 5V. Maybe those fan's are too big, but if I had a little one, I'd put it over the control circuits and rectifier.

I'm guessing the main PSU heatsinks have a fan already.

[tautech]

My 3303 must be over 3yrs old by now. I had it open already tho. Do these have a fan though ? I can't remember seeing one or ever hearing 1. I hardly ever use much power, so IDK.
I'm guessing the main PSU heatsinks have a fan already.

Yup, smart fan and at low power it will not spin up from its normally very low RPM.

But thanks I'll remember to check the rectifier next time I open it up. I bet it's due for a de-dusting too.

TBH don't worry about it until you have an issue which for some years we never did so maybe just a bad batch of rectifier bridges caused these problems.
I suspect design was using most of the 2A available from those tiny bridges and sus ones gave more failures.
Now with a much better bridge in the redesigned HW there should be now more problems. 

[opiwahn]

A warranty repair just done...installed the new version control PCB with uprated bridge rectifier.

I bought a brand new SPD 3303X-E (in Sept. 2023) and I wonder whether it could be affected by this reboot issue (up to now no problems yet). The hardware version is reported to be V6.1, can anybody tell me if this includes the uprated rectifier? I could open it up, but I don't want to break the warranty seal ... Thanks!

[tautech]

A warranty repair just done...installed the new version control PCB with uprated bridge rectifier.

I bought a brand new SPD 3303X-E (in Sept. 2023) and I wonder whether it could be affected by this reboot issue (up to now no problems yet). The hardware version is reported to be V6.1, can anybody tell me if this includes the uprated rectifier? I could open it up, but I don't want to break the warranty seal ... Thanks!

Welcome to the forum.

Check the display symbols when in Series or Parallel mode.
The newer HW has more than just a symbol shown in these modes.

[opiwahn]

In parallel and serial mode, there is an additional blue text field which displays the added voltage/current. Is it this text field I have to look for?

[tautech]

In parallel and serial mode, there is an additional blue text field which displays the added voltage/current. Is it this text field I have to look for?

Yep, indicates latest HW.

[44kgk1lkf6u]

I want to point out that it is not necessary to remove the broken bridge rectifier.  It breaks with 1 of its 4 diodes either being open or having a large resistance.  It is only necessary to add a good diode in parallel with the bad diode.  In my case the broken diode was connected to the fuse.  So I soldered a diode between the fuse holder and the linear regulator.  It is the SOIC-8 chip next to the fuse and the connector.

As this Florida man pointed out, it is hard to access the other side of the board to remove the bad bridge rectifier.

https://www.eevblog.com/forum/testgear/sdp3303x-hiccup/

[qpit3a]

Hi yeah true but given consensus is bridge fails due to heat and that it is under-specified then probably best to replace with upgrade as rest of bridge probably will fail eventually.