Re: Newbie - Imac 24 - Liteon PSU - no power at all
So haven;t had much time in pat few days to read up on things..but did get a light bulb in soldered in place of the 5 amp fuse so now I can ass power to the board and check for heat or wait for something to smoke.
Any idea how long I should plug this in for this kind of poor mans test?
And any tips on what to feel or even check would be great. I don't want to touch something that will give me a zap so haven't been playing with this setup until I learn more.
Thank you.
StraitNet
Member
Last Activity: 11-30-2014, 03:06 PM
Joined: 11-14-2014
Location: Northwest WA
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Re: Newbie - Imac 24 - Liteon PSU - no power at all
TELVM..thank you very much, that is a big help. Now once I can function tonight I have some more research and reading to do
Hope you had a happy T-day
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Re: Newbie - Imac 24 - Liteon PSU - no power at all
I just created an image showing different parts of this power supply board.
When I set my multi-meter to ohms (beep test) and check the legs on item B (both of them) I get no reading...no matter how I test them, straight across, diaganol etc.
Should I get a beep here? and what is this called?
Also if you can let me know the names of any other items that would be great.
Thank you and Happy Thanksgiving...
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Re: Newbie - Imac 24 - Liteon PSU - no power at all
Ah..
Thermal compound and heat sinks..those are the terms I was looking for.
Now that I found an article on this stuff..it sure seems more complicated than I imagined.Leave a comment:
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Re: Newbie - Imac 24 - Liteon PSU - no power at all
So I have found info on how to test those Mosfets...but I am still trying to figure out what they are connected to and why?
Do I need to take the aluminum blocks all a part and remove each Mosfet before testing?
Is there any sort of grease etc. on the mosfet contacts? similar to CPUS (cant think of what that is called right now)
Thank you for all help so far...I am trying
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Re: Newbie - Imac 24 - Liteon PSU - no power at all
It looks like all the black things with three legs are bolted to aluminum cooling blocks or something....is that right?
Just making sure I google for the right thing to figure out how to test for shorts.
ThanksLeave a comment:
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Re: Newbie - Imac 24 - Liteon PSU - no power at all
Do I just check for continuity? Sorry not sure what to check..or how
Update:
I also just did another test..
I replaced the fuse again and had everything unplugged..Except the power in clip (two wires blue and brown) before trying to give it power.
As soon as I even touched the outlet the same fuse popped again...didn't even have to plug it in.
So it must be a short on the Power supply I am "thinking".??
Not sure where to go from here...Leave a comment:
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Re: Newbie - Imac 24 - Liteon PSU - no power at all
Update:
I finally got the pack of fuses in the mail today, re-soldered a new one to the power supply board and as soon as I turned it on..POP goes the new fuse
I am searching and searching on how to trace a board out..check for shorts, bad MOVS, CAPS, etc. (still foreign language to me).
If anyone wants to give this newbie a head start it would be greatly appreciated.
Thank you.Leave a comment:
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Re: Newbie - Imac 24 - Liteon PSU - no power at all
Selldor...I just didn't know what the expected voltage was on that given power supply so I was just trying to get a reading anyway I could. There was no markings or info on the internet for that supply. Someone ended up helping me out and telling me the voltage looked good though.
I have watched many youtube videos this year but still most of it is over my head since I haven't got the basics down yet and most people in the videos use much higher quality testers with different dials or functions it seems.
...Leave a comment:
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Re: Newbie - Imac 24 - Liteon PSU - no power at all
That was just a photo I had already showing voltage on another power supply.
I will be cleaning the fan once I get my compressor back home
Spent today digging out the various boards I had been saving for a day that I could learn this stuff...and also pulled open a few other power supplies to see if I could find this same fuse..no luck of course....Leave a comment:
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Re: Newbie - Imac 24 - Liteon PSU - no power at all
I only had my meter on the setting that would beep if there is continuity..didn't check ohms...mainly because I didn't know to do that...sigh
and the other stuff you mentioned is still a foreign language to me as of now...lol That's what I want to try and learn how to do or test.
Thank you....Leave a comment:
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Re: Newbie - Imac 24 - Liteon PSU - no power at all
Did I test this fuse properly? and is it bad if there's no beep when I touch both contacts with my tester?
Also would a power surge cause this to blow or just a short somewhere?
Thank you....Leave a comment:
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Re: Newbie - Imac 24 - Liteon PSU - no power at all
I may be way off here but just pulled out a magnifying glass and looked around the board.
Next to the AC input there is a small black box that reads:
T 5A 250V
I flipped the board over and checked between each post on that box for continuity and got nothing.
Is this by chance a fuse that could be blown?Leave a comment:
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Newbie - Imac 24 - Liteon PSU - no power at all
Hi all...I have very little experience when it comes to troubleshooting boards but have always wanted to learn.
Yesterday I picked up an Imac 24 for $20 that wouldn't power on and figured it was a good first project.
[B]Imac 24 A1125 - PSU is Liteon PA-3241-02A Rev: A[/B]
So far I have checked that it has power to the incoming line that plugs into the power supply board.
It has NO l.e.d. lights so it's not getting a trickle charge.
I can't see any caps that have bulged tops.
I will attach a photo of the multi meter I have..again... -
Re: New Members - please post your introductions here
Hi all, My name is Christian, just turned 40.
Jack of all trades, master of none.
Seems like every week I come across something that won't power on and really want to learn how to troubleshoot.
Have had one successful fix on my parents LCD TV, repair man wanted almost $400 and thanks to the Internet I fixed it myself for $1.70 and saved it from the landfill..it was my first and only soldering job so far.
Going to learn a lot here I think
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