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Stj, sorry for gap... I have not forget to feedback soon.
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Maybe this:
BZX584C15
[URL]https://www.alldatasheet.net/datasheet-pdf/marking/1447282/DAESAN/BZX584C15.html[/URL]
You are on it...https://Maybe this:<br /> BZX584C15<...n it... :wink:Maybe this:
BZX584C15
[URL]https://www.alldatasheet.net/datasheet-pdf/marking/1447282/DAESAN/BZX584C15.html[/URL]
You are on it...Last edited by harp; Yesterday, 04:48 PM.
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Have you see:
[url]https://www.eevblog.com/forum/testgear/owon-hds-200-handheld-oscilloscope-w-builtin-dmmawg/675/[/url]https://Have you see:<br /> [url]htt...awg/675/[/url]...
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I have not low-ohms meter to see if is capable to find 85R in parallel... maybe, but it must be very precise and wide range...
I try to inject volteges and see if any difference I can spot, on faulty cap or other. My dmm have 4000 count, so on 3V it show milivolts. Not a tiny difference for sure between all caps in rail while measurement cant see.
I hoping that the current path can be detected somehow, without modifiing pcb, so I inject pulsed 3V about 4kHz 75% and try searching some magnetic field with loop... but nothing again. Maybe different probe? Hall sensor?
I have not...
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How to locate high value short component
It is not so important rather then discusion... for learning.
I have small box where put bad components in it, shorted diode, caps, burned resistor etc. I was trying to do some yt video about tracing shorts, so, I use one of these bad smd caps from box... it has few ohms, idealy for presentation... I put him on a known good pcb board, on 3.3v rail, parallel with other caps... but, after it cools down, the rail has 85 ohms... when I apply power, it took only 35mA and no voltage drop... so 0.1W...
Any idea, your experiance how to find 85R bad caps technique?...
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In diode mode measurement, power must be disconnected, to get proper reading. I not sure even if on that setup you can cause any damage to dmm or device if device is powered.
But, I think and feel that root of your problem is cause by poking arround with probe tip while the power is connected. You must be extremly careful if your measurements is took from eg. qfn leg dirrectly, to not move (roll) tip between measurement leg and one by side. To damage chip while it is in power up state, there be suficient only one probe tip on wrong place - about 0.2mm distance from right measurement...Last edited by harp; 07-10-2024, 07:04 AM.
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I have a small second hand TV, that I rarely used as a filming monitor. When I open it for initial cleaning and inspection, I noticed that for main IC is used very small heatsink which was directly glued on IC (just like on yours), not side suport on pcb whatsoever... On other side of pcb, the board was starting browning from heat, so, any mess around with glued heatsink or IC is not anymore option due to pobably ripped pad under bga... I use a small thin turbine (side type, with partialy housing) fan from old graphics card like attachment and connect it to usb power, so it is on while is TV on,...
Last edited by harp; 07-08-2024, 12:53 PM.
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You see on bottom pcb trace signature, and on top is black package, combined with 220v heater what else could be...
[url]https://www.eevblog.com/forum/beginners/blown-heated-blanker-controller-trying-to-figure-out-these-smd-resistors/?action=dlattach;attach=2302253;image[/url]
Thyristor... 2P4M
Op is lazy... (:https://You see on bottom pcb trace ...53;image[/url]
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There is a three pin triac near display, but when I see fault like this, where a few resistor disapear and where these was directly connected to controller... first disconnect that leg of ic, and see if you have diode junction reading to any other. Probably not, and thats is end of story designed to serve newnormal ideas of light green eco ic suicide.
It is sadly to say in this modern time - make your ovvn controler with discrete riggid parts which you can repair if you need.
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One rapid LED light pulse per press of push button switch circuit using 2N3904 NPN BJT
Just adjust capacitor to desired time interval, like 10uF or 22uF......Last edited by harp; 07-05-2024, 10:53 AM.
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If transistor is closed (blocked), on collector (one side of resistor) and on positive rail (other side of resistor) you have 5V on both point respect to ground, so, between them there is no difference in potential at all - 0V. Thats why you dont measure voltage accross resistor, in general....Last edited by harp; 07-05-2024, 05:35 AM.
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From where? Investigate what is source in this moment?
If you put LED like I say, is it act also like that? Your real load, relay definitely dont do that, there is no power for that.
But I want you to realize that in general electronic control and regulation circuit is not intended to be designed to control (operate) withot power, or in lack of it. 555 pin#4 cant operate correctly without powered ic already. If you have some power on board all the time, that must be using to control circuit, the signals and sense must be apart of that. Maybe to consider redesign circuit?...Last edited by harp; 07-05-2024, 05:21 AM.
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I dont know what you mean... accross 10k... on collector (respect to ground) is normally 5V if transistor is not powered on.
Are you simulating this circuit, or you actualy built it on testboard?
Have you large capacitor on power rail with you try to control circuit?
You shall measure between 555 pin#3 and ground.
When you designed a new circuit, allways start from basic circuit, and gradualy develop with stable modules, so, get rid of transistor at the moment, and on output connect 470 ohm resistor in series with one LED to ground.
See:
[url]...Last edited by harp; 07-04-2024, 03:34 AM.
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I am not quite happy when comes identification by datasheet only... sometimes is provided only "textual" information not supported by aligned or style, symbols.
I like to find exactly same photo of element with same alignement and style of printing from sellers offer. Then their description have more sense.
The more photo have WY markings only, not side date code, and this mean caution.
I found similar picture that confirm aligned style and datecode position correctly.
[URL]https://www.edaboard.com/threads/smd-component-can-anyone-identify-these-two-smd-diodes.395459/[/URL]...
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I think I have found what I am looking...
What is transil?
EDIT
Ok, TVS diode......Last edited by harp; 07-02-2024, 05:05 AM.
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I look and steirs at datasheet... and nothing... I can not see how to determine what component is "better"... for different point of switching...
Anyway, all videos presents control triac in therir narrow midrange or so, I can not clearly see to one circuit that fully start at beginning after zero cross and control cutoff till end.
Now I found that switching phase can be control in reverse order also, so it is interesting point to me, it not shock end device so much, but nothing to conclude how circuit look...
For control mains transformer primarry windings,...
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