Re: Troubleshooting AC/DC circuit board
There's a chip on board next to BD1. I assume this is the Bridge Rectifier?
Testing this with ohm meter setting at 200ohm. Tried to test all for legs and couldn't get any reading out it.
Could this be the culprit?
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Re: Troubleshooting AC/DC circuit board
i'm a bit in experience when it comes to visual inspection. But I just tried resolder the crack as shown in the red circle. Doesn't do it...still same problem.
Which component is the bridge rectifier? There are several IC chips, can any of these be the culprit? Is there way to test for these?
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Re: Troubleshooting AC/DC circuit board
yes 160VDC is measured but only the radial caps was replace didn't know about the other that need to be replaced. which one are they? do u think they are bad as well?Last edited by soyuppy; 05-19-2015, 02:21 AM.
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Re: Troubleshooting AC/DC circuit board
pics with new caps...
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Re: Troubleshooting AC/DC circuit board
no, I have 3 boards that have the same problem. Right now just focusing on getting one board working. So I have all the caps replace on this one board that has good fuse.
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Re: Troubleshooting AC/DC circuit board
Back with updates.
Got all the caps replaces with Panasonic FR series. Match each new cap with the same spec as old one.
But still not getting any power output on both lead.
Any other suggestion where to trouble shoot.
I've been reading a lot on switch power circuit. Most point out that sometime noise would generated from rectifier.
But it's not the case here. The PSU is dead silent.
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Re: Troubleshooting AC/DC circuit board
when red lead touch black lead, show zero.
When red lead touch top of fuse and black lead touch bottom of fuse, show 1....
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Re: Troubleshooting AC/DC circuit board
May be I'm confused on what shorts.
But fused is tested on Ohm reading. It shows open(1) on meter. So fused is blown. Need to be replaced....
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Re: Troubleshooting AC/DC circuit board
yep...did that...and yes, it's shorts....
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Re: Troubleshooting AC/DC circuit board
Thanks for the info. Yes, there's black heatsink tube right next to the main entrance. And removing the heatsink show indeed a fuse. It's pretty small and hard to tell that's its short...but I'm pretty sure it's short.
But I'm more interest in how to remove/replace this fuse. From the look of it, I should be able just remove the fuse leaving the lead join on the board. But seems like the top cap are glued into the fuse. Try to wiggle for movement, but doesn't budge.
Do I have to remove the entire housing...
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Re: Troubleshooting AC/DC circuit board
I was probing the caps...and then it just sparkle. Wasn't sure what it was...until i see the black charred. I decided to disconnect and kind of don't want to do anything else now
Will re-soldering cover the trace burn out? If I resolder and reconnect, how do I tell/test if transformer still operating? can I read it off volt meter? there's a lot of lead wire onto the board...wasn't sure which wire to tap on the volt meter.
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Re: Troubleshooting AC/DC circuit board
not sure what to make of this. Appreciate any pointer...
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Re: Troubleshooting AC/DC circuit board
In the process of testing and out the output from various capacitor, spark fly and this happen. See pic
The blow lead belong to the transformer...the big block module sitting in the middle of the board.
Does this mean it's bye bye? Or can I just resolder it? How do I test transformer....
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Re: Troubleshooting AC/DC circuit board
Old gun had over 20 yrs now. Can't tell what wattage anymore because the label is all washed out. Chances are it's not lead free and the board probably use lead free which require more heat/new gun.
I'm also using the wire mesh/braid to remove the solder.
Will look into new soldering gun. Anyone to recommend? Seen Weller on Amazon but they are a bit $$$.
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Re: Troubleshooting AC/DC circuit board
Well, I hope it's ok to continue this thread on different topic/question.
I'm trying to remove the cap from the board. My soldering gun can't seem to melt the old solder. But it can melt new rosin-core. Does this mean I need a new gun with more power just to melt the old lead on the board?Last edited by soyuppy; 03-29-2015, 12:55 AM.
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Re: Troubleshooting AC/DC circuit board
thanks for the advice. Will look for Pan FR series from either Amazon, DigiKey or Mouser.
Probably will replace all the caps, including one in the primary as suggest by @stj. But in doing so, I will need to remove and reseal the white caulking material as well?
What is this material call?
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Re: Troubleshooting AC/DC circuit board
more pic of top and bottom as requested
159.99VDC is measure on the capacitor...
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Re: Troubleshooting AC/DC circuit board
Forgive me as I very new at this. Can I use a 47uF 50V to replace this 47uF 35V do I have to find the exact 47uF 35V?...
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Troubleshooting AC/DC circuit board
Not sure if this is the right forum. It's it relating to AC/DC circuitry. Figure its in the same domain as PSU.
I have fault AC/AC circuit board. 2 different DC voltage are output. One is 3.3V and another is 14.8V.
Upon inspection, nothing looks burned and caps look clean. Doesn't look like there's any faulty component.
Understand typically there's fuse, but can't seem to find the fuse box either. I have confirmed output from the AC housing prior to entry onto the IC is in tact with ~120VAC.
Where would I start to diagnose this board?...
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