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#1 |
Badcaps Veteran
Join Date: Dec 2013
City & State: Tathra, New South Wales
My Country: Australia
Line Voltage: 230VAC 50Hz
I'm a: Knowledge Seeker
Posts: 398
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![]() I know these things are only worth a few dollars, so this is perhaps more an intellectual exercise in understanding what is (not) going on here.
The model is marked as MP-3314, sold in our consumer electronics stores, and is variable between 3V and 12V at 1.5A. Under no load it shows as the appropriate voltage - set currently at 9V. But under load it fails, the LED flashes/blinks as it tries to restart. Meter shows volts come up but fall back with a fraction of a second, repeated continuously. What would be a typical component that would fail, producing this effect? Images attached of both sides of board. By the way, have confirmed the device it is driving is OK. I have wired in my bench variable supply and all works 100% |
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#2 |
Great Sage 齊天大聖
Join Date: Dec 2009
City & State: Europe
My Country: some shithole run by Israeli agents
I'm a: Professional Tech
Posts: 26,399
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![]() 3v @ 1.5A
probably means 6v @ 750mA and 12v @ 375mA whats your load and where is the primary's heatsink? ![]() |
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#3 |
Badcaps Veteran
Join Date: Jun 2012
City & State: ☻
My Country: Canada
I'm a: Professional Tech
Posts: 7,959
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![]() There is a small value electrolytic in the primary I would replace first, In your picture it is the one located next to the transformer below the mosfet.
Last edited by R_J; 02-19-2022 at 09:02 PM.. |
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#4 |
Badcaps Veteran
Join Date: Jan 2015
City & State: worcester
My Country: United Kingdom
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Posts: 3,209
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![]() clean the solder side of the board and resolder the bad joints
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#5 | |
Badcaps Veteran
Join Date: Dec 2013
City & State: Tathra, New South Wales
My Country: Australia
Line Voltage: 230VAC 50Hz
I'm a: Knowledge Seeker
Posts: 398
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![]() Quote:
And what you see in the images is what you get. No heatsink to speak of. I think you are probably correct. Simply can't supply the required load. I found a 12V 2A plugpack in my junkbox and gave that a go. It powers up and runs. But there is a oscillation tone coming from the speakers that is reasonably prominent. Hard to image that 3 volts would make much difference? But I certainly didn't hear any of that when I was running it off 9V from my bench supply. Just cheap and nasty electronics all around I suspect. |
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