tester001
Tony
Last Activity: 12-31-2023, 06:59 AM
Joined: 12-06-2023
Location: London
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So it's not abnormal for the whole circuit (with mosfet and cap removed) to show at its input (the prongs) the resistance I specified (1.795 kOhm and if I switch the probes around it - 34 kOhm)?... -
Not yet, as I couldn't identify its model and therefore wasn't sure how to test!...Leave a comment:
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Yes, Mosfet has been out (as pictured a few posts above) and the little yello cap that was above the prongs is now out too...Leave a comment:
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Hi [USER="132583"]CapLeaker[/USER],
Sorry! I've not been very clear. The removed capacitor is showing resistance of 4-5 MOhm and counting. Unable to get capacitance reading.
The 1.795 kOhm and if I switch the probes around it is 34 kOhm resistance readings are now across the prongs [ATTACH=JSON]{"data-align":"none","data-size":"full","title":"image.png","data-attachmentid":3170436}[/ATTACH]​ with capacitor removed.CapLeaker...Leave a comment:
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Thank you for your suggestion!
I've taken the capacitor out of the circuit and the meter fails to get a capacitance reading (I gave it time!):
[ATTACH=JSON]{"alt":"Click image for larger version Name:\timage.png Views:\t0 Size:\t563.9 KB ID:\t3170293","data-align":"none","data-attachmentid":"3170293","data-size":"custom","height":"335","title":"image.png","width":"493"}[/ATTACH]
The resistance across the [I]input [/I]prongs...Last edited by tester001; 12-30-2023, 09:45 AM.Leave a comment:
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To everyone who has been celebrating - Merry Christmas!
With help from colleagues I have desoldered the mosfet from the buck converter board and the resistance across the input terminals is now 159 Ohms.
[ATTACH=JSON]{"data-align":"none","data-size":"custom","height":"297","title":"image.png","width":"272","data-attachmentid":3168880}[/ATTACH]​
Should it have increased after de-soldering the mosfet if that component was broken? Just trying to understand...Leave a comment:
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I could, but I usually connect its output to the module that controls the LED - I'm worried that I might damage it if I supply, say, 48 volts instead of 40.
Not sure what to do really. I've ordered this buck converter [URL]https://www.aliexpress.com/item/1005004336673431.html[/URL] but I suspect it would crumble when having to deliver 30 W to the LED, even if I install the heatsink.
There is no room within the case for a larger, more powerful buck converter or an adjustable Mean Well PSU model that outputs 40v.
Whoever designed this device felt that this little board was...Leave a comment:
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Turning the SVR1 knob on the PSU made absolutely no difference to the voltage read on the CN2 outputs - it stayed at 47.8 V
[ATTACH=JSON]{"data-align":"none","data-size":"custom","height":"269","title":"image.png","width":"492","data-attachmentid":3164199}[/ATTACH]​
What does this resistor actually do?Turning the SVR1 knob on the PSU made absolutely no difference to the voltage read on the CN2 outputs - it stayed at 47.8 V
[ATTACH=JSON]{"data-align":"none","data-size":"custom","height":"269","title":"image.png","width":"492","data-attachmentid":3164199}[/ATTACH]​Leave a comment:
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Could be! I replaced the little board with this:
[ATTACH=JSON]{"data-align":"none","data-size":"custom","height":"242","title":"image.png","width":"779","data-attachmentid":3164191}[/ATTACH]​
And set the adjustable power supply to output 40V with 1.5A max. The LED device sprung to life!
I ran it for a while in different modes and noted that it didn't draw more than 38W in power (as displayed at the adjustable power supply above).
I don't know....Leave a comment:
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Based on the overview of the components and its placement within the device, can you tell what the little board does?
[ATTACH=JSON]{"alt":"Click image for larger version Name:\timage.png Views:\t0 Size:\t244.8 KB ID:\t3163858","data-align":"none","data-attachmentid":"3163858","data-size":"custom","height":"646","title":"image.png","width":"921"}[/ATTACH]
[ATTACH=JSON]{"alt":"Click image for larger version Name:\timage.png...Last edited by tester001; 12-16-2023, 01:43 PM.Leave a comment:
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I think you are right, as I have just received a replacement PSU and I get the following results with it:
PSU plugged into the mains and switched ON - no chirping
little board soldered on - chirping starts
It is 290 Ohms!
[URL=filedata/fetch?filedataid=321115][ATTACH=JSON]{"data-align":"none","data-size":"custom","height":"132","title":"image.png","width":"176","data-attachmentid":3160954}[/ATTACH][/URL]
...Leave a comment:
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Something strange happened. I've been testing continuity with a Fluke meter and couldn't get any current flowing through the diode no matter how I connected the probes (in case I mixed up the polarity):
[URL=filedata/fetch?filedataid=320851][ATTACH=JSON]{"data-align":"none","data-size":"custom","height":"97","title":"image.png","width":"105","data-attachmentid":3159480}[/ATTACH][/URL]
Then a colleague tested the diode with this thingie and it now works correctly on Fluke too:...Leave a comment:
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Thank you very much! After reading up more about the subject I found a diode next to the capacitors and it failed basic diode tests (wasn't passing current in any direction)
Datasheet: [url]https://cdn.badcaps-static.com/pdfs/86a245b4d1c41a678eadb71c6b8e6590.pdf[/url]
Shall I try to replace the fast recovery diode and put the capacitors back? Is it OK for 63V 470 uF capacitors to be reading 400 uF and 410 uF​?
Thanks again!https://Thank you very much! After r... tests (wasn't...Leave a comment:
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It's an LED driver PSU
I've just tested the two 63V 470 uF capacitors:
one is reading 400 uF
the other 410 uF
Would this be sufficient to cause the described fault?...Leave a comment:
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Sorry, I'm a total newbie. What does 'shorted in the secondary' mean?...Leave a comment:
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I read your '240v is fine - only the wattage matters' as 'voltage doesn't matter'
Thank you, I will de-solder them and get them tested (will check online for methods)...Leave a comment:
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I have no clue of what I'm looking for, but I used the search on this website and found this:
[ATTACH=JSON]{"data-align":"none","data-size":"custom","height":"658","title":"image.png","width":"656","data-attachmentid":3158942}[/ATTACH]​
Does this mean that the pictured caps are bad and should be replaced?I have no clue of what I'm looking for, but I used the search on this website and found this:
[ATTACH=JSON]{"data-align":"none","data-size":"custom","height":"658","title":"image.png","width":"656","data-attachmentid":3158942}[/ATTACH]​Leave a comment:
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I've connected the output of the PSU to an old projector bulb (8V 50W) and got the "chirping" again!
[ATTACH=JSON]{"alt":"Click image for larger version Name:\timage.png Views:\t0 Size:\t1.18 MB ID:\t3158934","data-align":"none","data-attachmentid":"3158934","data-size":"custom","height":"381","title":"image.png","width":"286"}[/ATTACH]
Do any caps on this PSU look like they need replacement? If not, should I desolder them one-by-one...Last edited by tester001; 12-07-2023, 09:27 AM.Leave a comment:
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Thank you for the suggestion! You mean a 48v/25W filament light bulb would do for the test, correct? Does it have to be a 48V bulb or any filament bulb between 25-40W?...Last edited by tester001; 12-06-2023, 09:39 AM.Leave a comment:
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