What would you do if you have got a couple broken Switch Mode Power
Supplies, a screw driver and some curiosity!? Well obviously you would
crack it open and try to figure it out. I have to admit, we would
probably have opened them before they were even broke. That is exactly
what I did.
[sc name=”begin_of_toc”]
SMPS schematic using IC2003
SMPS schematic using IC KA7500
SMPS schematic using TL494 and LM339
Datasheets
Links
[sc name=”end_of_toc”]
When I had a couple of them lying around, I cracked them open and after a few days, fixed some of them. It was actually much easier done than said. But one bad thing about SMPS repairs is that there aren’t any good resources out there on the web. (OK may be there are, but I failed to find some). That is why I decided to make a series of posts with my repair notes, schematics and stuff I have learned through opening those bricks. Being the first post, this is the schematic post. You can grab the schematics available on the net here. Please send me a link if you have found a new schematic and I will add it here.
Thanks goes to : http://electro-tech.narod.ru
This schematic along with the low quality parts is normally seen in
Mercury branded SMPS. I have 6 of those lying around. All with blown
caps and no EMI filter. EMI filters are not much of a concerns usually
for ratings below 350W. But a good engineer /designer will always add
an EMI filter.
The manufacturer has omitted this along with output filter coils to cut costs.
Click on the images to enlarge. If you know anything about Switching
Power supplies, the schematics are quiet obvious. They are simple.
Include simple protections and have very few components.
[sc name=”begin_of_toc”]
When I had a couple of them lying around, I cracked them open and after a few days, fixed some of them. It was actually much easier done than said. But one bad thing about SMPS repairs is that there aren’t any good resources out there on the web. (OK may be there are, but I failed to find some). That is why I decided to make a series of posts with my repair notes, schematics and stuff I have learned through opening those bricks. Being the first post, this is the schematic post. You can grab the schematics available on the net here. Please send me a link if you have found a new schematic and I will add it here.
The Schematics
There are two circuits commonly available for PC ATX SMPS.- Based on IC2003
- Based on KA7500
- Based on TL494 and LM339
Thanks goes to : http://electro-tech.narod.ru
SMPS
schmatic using IC2003. The cheap Chinese SMPS uses a circuit based on
IC2003. The EMI filter and output filters are usually left out, and the
components heavily underrated. The schematic is hard to find, not drawn
by me.
The manufacturer has omitted this along with output filter coils to cut costs.
Here
is an SMPS based on IC2003 after repairs. I found some inductors to add
to the output filter, but couldn't find any for the EMI filter at
input.
SMPS schematic using IC KA7500
The TL494 LM39 combination was the most widely used one till recently.
