Reply With QuoteWhat is it out of and what are the input/output voltages and current capabilities?
power supply replacement
Hi there,just wondering if there is a member out there that could tell me if it is possible & where to buy a replacement"model M280LS"power supply board.
thanks in advance.
wyndham1
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What is it out of and what are the input/output voltages and current capabilities?
re power supply
thanks for the reply studio the supply came from a dreamax dm470 sat receiver the secondery pinout voltage`s are 30v 6 22v 5v 12v 7v 6 3.3v 6 respectevly
thanks for any info
wyndham1
Repair it ? It's only a machine !
Chances are it's a generic supply made in China by the millions and used in various models of Sat receiver.
I doubt very much you'd get one locally unless someone has a junked unit that has a good supply in it.
I find with this kind of stuff that distributors and agents don't really carry any spares - if the unit dies, they bin it and give the customer a new one.
repair or not?
thanks for your help guys,i will have a look at repairing its`just not worth it most of the time,right about being generic i have seen them before.never had 1 come back though with power supp prob,always a first eh!
Most SMPS are fairly reliable - even the 'Made in china' ones.
Where THEY fall down however is far too tight working tolerances on components.
For example, if they make something that has a 24 volt rail in it, they'll use a 25 volt capacitor on that rail, because a 35 volt cap is dearer!
Naturally, the cap is operating at or as close as you can get to its limits and will undoubtedly fail within a short time (as they do).
If you are going to attempt to repair it, start by replacing all low value electro caps - ie anything under 100uF.
Check all semiconductors for shorts. Check all resistors for high value or open circuit.
Little else goes wrong. Have had the occasional feedback optocoupler do weird things.
smps startup
Check that the starting resistor/s have not gone high.. that is often there are a few high value resistors that form a divider from the main storage cap thus it will drop 360V+ to a few volts. This provides a rail for the smps control at start up and its common to find an o/c 470k resistor or similar.
Some times there are ceramic fuses that blow. They dont look like a normal m205 fuse but more like a euro rb cap just to trick the unsuspecting.
Above all BE CAREFULL! remember the HOT side of the PSU 0V is +175v above earth and the main storage cap will have at least 360V across it.
Generaly if you power up the smps and you have high voltage on the cap you could be confident the main chopper is not blown. Check the inrush resistor is not o/c on the hot side of the supply.
Good luck, use your isolation transformer... good for prolonging life in the w/shop
jinxed
Hey after reading this post the net day what comes thru the door? dead psu in a dvd player, simple psu with a 3 rails, the electro was dead on the main 5V rail. Had a mix of 85&105deg caps? on the secondary the dead one was a 1000uf 10V 85deg in a nice warm spot. cheerzOriginally Posted by Studio1
No worries - glad I could be of some help. That was something I forgot to mention as well - a lot of cheap electronics (read "made in china") use 85°C caps because they are somewhat cheaper than 105°C caps.
When replacing, always use 105°C caps throughout. It's the heat that causes caps to dry out and exhibit weird characteristics.
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