350w SMPS troubleshooting. - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 29th April 2011, 08:18 PM   #1
mb3 is offline mb3  United Kingdom
diyAudio Member
 
Join Date: Dec 2007
Location: UK
Default 350w SMPS troubleshooting.

I have a meanwell clone s-350-36, which has broken, IIRC due to crossed speaker cable. I would like to fix it both for use and to improve my understanding. I have tested the defective unit and mapped the voltages across the board
Click the image to open in full size.
Areas without colour tested as 0 V.

I have tried to overlay this over the front face of the board too;
Click the image to open in full size.

And here is the front with no overlay;
Click the image to open in full size.

So to me it seems that the most likely broken component would be the small yellow/black part above the space between the two large capacitors, as this seems to have power one side but not the other. Which i believe is a transformer?.

Does this seem likely?
Is it something that would likely be damange by shorting speaker cable (or possibly one terminal hanging loose)?

Would you expect further damage to other components??
If so is there anything i can do to test that without risking breaking another transformer(?). ?

If it is a broken transformer, how do i go about replacing it (cheaply)? .. how do i know which type? the only thing i can see written on it is S 6.
Is this something that can be DIY'd?

Thanks in advance.
  Reply With Quote
Old 30th April 2011, 07:58 PM   #2
diyAudio Member
 
Join Date: Nov 2005
Location: Mauritius
Hi i've seen your post. Am not an SMPS expert but am struggling my way through. That black and yellow transformer is if am not mistaking a gate drive transformer. Its purpose is to provide the driving signal to your power transistor or power fet and to isolate the SMPS chip and driving circuitry. up to now i've blown fuses and power fets while building my SMPS but never that transformer. It cannot be replaced blindly as its custom made for your PSU frequency and tuned for your power switch driving signal

From your voltage mappings(RED shaded tracks) the input section might be OK your fuse does not seem to have blown.

Now normally there are protection circuits in SMPS (over current, over voltage, under voltage over temperature, e.t.c) which trigger in case there could be a fault in the SMPS. They will to keep it simple prevent the psu from turning on. if you are getting voltage on part of the drive transformer it could be one of your power switch or both has failed. POwer off the circuit, let the mains cap discharge and check these switch.

For your info two very important points, that PSU you have here seems to me like a half bridge. You can search on this on the net and get tons of info on how it works.

Last but not least to built or repair a psu an oscilloscope is needed, its really hard to deal with SMPS without one handy as all the problems in an SMPS can only be diagnosed through the waveforms its producing

I have labelled some of the sections from what i could recognise visually in the attached file
Attached Images
File Type: jpg pH3sG.jpg (231.7 KB, 463 views)

Last edited by zeus_threat; 30th April 2011 at 08:07 PM.
  Reply With Quote
Old 7th May 2011, 07:18 PM   #3
mb3 is offline mb3  United Kingdom
diyAudio Member
 
Join Date: Dec 2007
Location: UK
Thanks for your reply and image!.. sorry for my delay.

Is an H-bridge the same as a half bridge?? Can anyone point me to a good learning resource on this?

How do i check the power switches aren't broken exactly??
  Reply With Quote
Old 13th May 2011, 11:45 PM   #4
mb3 is offline mb3  United Kingdom
diyAudio Member
 
Join Date: Dec 2007
Location: UK
Quote:
Originally Posted by mb3 View Post
How do i check the power switches aren't broken exactly??
Anyone?

Would one of these; ebay: 2 Channel PC Computer USB Digital Storage Oscilloscope be suitable?

And what would i be doing with a 'scope in this scenario and how would that bring me closer to a solution?
  Reply With Quote
Old 19th May 2011, 04:23 PM   #5
diyAudio Member
 
Join Date: Nov 2005
Location: Mauritius
You seem not to be well used with those things it can be dangerous for you. I would advise to get it repaired at a electronics service workshop it will be easier. That scope is not good for the job anyway
  Reply With Quote
Old 19th December 2011, 02:41 AM   #6
! is offline !  United States
diyAudio Member
 
Join Date: Jun 2005
Location: Midwest
I really hate trying to trace faults from pictures but... it looks a bit like you've measured voltage on one side of the main (larger) transformer, did you not continue trying to measure voltage on the other side, or was there no voltage present? See if any voltage is present on the output rectifier's pins.
  Reply With Quote
Old 1st February 2012, 09:15 PM   #7
diyAudio Member
 
Join Date: Dec 2011
power supply troubleshooting and repair guide
SMPS Troubleshooting Techniques
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
smps troubleshooting holper Power Supplies 0 10th March 2011 07:44 AM
smps troubleshooting holper Power Supplies 0 10th March 2011 07:22 AM
Wtb: 36v 350w smps[eu] igor0203 Swap Meet 2 5th June 2010 08:48 AM
SMPS Power supply 350W 100v CT Regulated Bent Swap Meet 0 25th August 2005 08:57 AM
SMPS troubleshooting Loial Power Supplies 3 5th August 2005 08:37 AM


New To Site? Need Help?

All times are GMT. The time now is 11:51 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2