Electronics > Repair

Siglent spd3303x-e reboot problem

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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:

--- Quote from: tautech on June 17, 2023, 07:51:34 pm ---
--- Quote from: Faranight on June 17, 2023, 03:42:10 pm ---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.
--- End quote ---
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.

--- End quote ---

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

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