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What is this part?!

Harrison U

Aug 4, 2018
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Hello all, I received an old benq LCD screen that isn't working. I have pulled it apart and from what I have read on other websites, the problem is probably due to a bulging capacitor (which I have identified). My question is, that near the bulging capacitors is another part that looks to have been destroyed. it is a coil of copper wire arranged in a horseshoe shape, and it is covered in heatshrink. the part number is 1J 40229.041 - TC 1214. I'll include a picture. Can anyone tell me what it is? (the picture is of one that is fine across the opposite side of the PCB)

WIN_20180805_08_47_23_Pro_LI.jpg
 
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KJ6EAD

Aug 13, 2011
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That's toroidal. Misspelling doesn't always work in searches.
 

Harrison U

Aug 4, 2018
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Thanks for that, does anyone know how to make one or where to buy one with my specific requirements ?
 

Tha fios agaibh

Aug 11, 2014
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Does anyone know how to make one or where to buy one with my specific requirements ?
It's probably fine. They are supposed to look like that. That is shrink tube plastic you see over it and the exposed conductor is not a problem.
 

Harrison U

Aug 4, 2018
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Sorry, i meant the one on the opposite side (the one i took a picture of was fine but the other one was burnt out and destroyed)
 

davenn

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Sorry, i meant the one on the opposite side (the one i took a picture of was fine but the other one was burnt out and destroyed)


well it would have been helpful if you had shown the faulty one, aye ? ;)

unwind the wire off it, counting the turns and replace with new enamelled wire of the same or close swg
 

Harrison U

Aug 4, 2018
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Thank you very much. Sorry about that, should have put a pic on there I know. I counted 35 turns. Do I use copper wire or what?
 

kellys_eye

Jun 25, 2010
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The inductor only burned out for a reason - a very 'dangerous' reason (like a short circuit somewhere).

Have you identified the original cause of the problem? If not, you'll just be encouraging the replacement coil to go the same way (if not create even more issues).

The bulging capacitor issue is a common one and replacement usually fixes THAT issue but for a burned out inductor (which could be part of an SMPS inverter (buck or boost) circuit) you have a more significant issue to fix....
 

Harrison U

Aug 4, 2018
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The inductor only burned out for a reason - a very 'dangerous' reason (like a short circuit somewhere).

Have you identified the original cause of the problem? If not, you'll just be encouraging the replacement coil to go the same way (if not create even more issues).

The bulging capacitor issue is a common one and replacement usually fixes THAT issue but for a burned out inductor (which could be part of an SMPS inverter (buck or boost) circuit) you have a more significant issue to fix....
Thank you very much for the warning. I want to stay safe. what is an SMPS inverter? should I forget trying to fix the screen? (i got it for free so no big loss)
 

73's de Edd

Aug 21, 2015
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Sir Harrison U . . . . .

Why for you no give us Ben q model number . . . possibly . . . . . is it being a GL2450 ?
If so, is this . . . . poor quality pic . . .being your power supply board ?

The opposite.cross board toroidal inductor is part of a pi network power filter on a 18VDC cold supply.
It is not an item to be bad, in the manner that it is functioning within that circuits design.
Commonly, in addition to the heat shrink surround, there may be some adhesive applied to it of a black or
daaaaark brown color. That makes the uninitiated want to think that a unit is burnt or has overheated and had some hot " pookie " flow out of it .

If your WHITE ceramic pigtail fuse, that is in in the proximity of the AC lines input connector is not . . . or WAS not blown and you find just that pooched capacitor, you might not be bad off at all.
Give the C? designation of the pooched cap and it's location on the board shot given . . . .relating to its closest nearby parts.

Ben Q Power Supply Board . . . .

s-l1600.jpg



73's de Edd
.....
 

Harrison U

Aug 4, 2018
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Sir Harrison U . . . . .

Why for you no give us Ben q model number . . . possibly . . . . . is it being a GL2450 ?
If so, is this . . . . poor quality pic . . .being your power supply board ?

The opposite.cross board toroidal inductor is part of a pi network power filter on a 18VDC cold supply.
It is not an item to be bad, in the manner that it is functioning within that circuits design.
Commonly, in addition to the heat shrink surround, there may be some adhesive applied to it of a black or
daaaaark brown color. That makes the uninitiated want to think that a unit is burnt or has overheated and had some hot " pookie " flow out of it .

If your WHITE ceramic pigtail fuse, that is in in the proximity of the AC lines input connector is not . . . or WAS not blown and you find just that pooched capacitor, you might not be bad off at all.
Give the C? designation of the pooched cap and it's location on the board shot given . . . .relating to its closest nearby parts.

Ben Q Power Supply Board . . . .

s-l1600.jpg



73's de Edd
.....
Hello, 73's de Edd, thank you for your reply. you are absolutely correct. it is, in fact, a benq gl2450 (i should have mentioned it). I'm sorry for the poor quality pic, the closest camera I had (although this sounds stupid) was my computer camera (as well as poor lighting :| ). I believed the inductor to be burnt out because the surrounding PCB was turned to a dark brown colour (as though it had undergone high heat) and the wires of the inductor were entirely black leading me to believe that it had been destroyed. I may have overlooked the fact that it could still have been in good condition. thank you for pointing that out. the inductor that I believed to be damaged is closest to the top left of the board (in your excellent picture). once again thanks for your reply, I appreciate it.
 

Harrison U

Aug 4, 2018
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73's de Edd, also how do I determine whether the ceramic pigtail fuse is blown?
 

davenn

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73's de Edd, also how do I determine whether the ceramic pigtail fuse is blown?


If your board is the same as the one that Edd posted the pic of,
that fuse just behind the power socket

use a multimeter in Ohms range …. it should be ~ zero Ohms
 

73's de Edd

Aug 21, 2015
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how do I determine whether the ceramic pigtail fuse is blown?
Take DVM in hand . . .place in ohms function. Observe the display to see the manner in which it displays an open circuit.
Short the wires test probes together to create a short circuit and see how the meter displays that condition . . .which will be close to a 000 reading , less the test lead lengths resistance.
NO power even near that AC power connector and then place test probes across the white fuse.
near 000 resistance . . .good fuse . . . . .open circuit display . . . .blown fuse.
( Hoping that it is not blown)

73's de Edd
 

73's de Edd

Aug 21, 2015
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Sir Harrison U . . . . .

A continuance . . .

I suspicion that this is the sequence of events that has played out over a d . . e . . l . .a . .y . .e . . d period of time.
The top left quadrant located . . . yellow taped up ferrite core transformer . . . is being the main power transformer for the unit.
Our interest is the top left corner of that transformer where there is a heat sink just above it with a dual power rectifier diode mounted to it and a brown electrolytic cap close to it and your intermediary "toroidal inductor " and yet another brown capacitor is very nearby.
A secondary winding from the transformer has one lead going to cold ground while the other feeds to the dual diode with the diode pair common cathode connection feeding into the + of one of the brown filter capacitors. and then the inductor goes between that lead and the + of the second brown capacitor, which finally routes over to be the supply for the backlighting of the display unit.
That first capacitor from the diode is getting the hell hammered to it from the strong square wave hitting it at 50-100,000 times per second. After years suffering thru this, it is gradually declining its capacitance and starting to run hotter. With heat, some of the damp internal electrolyte might build up enough pressure to vent by gassing and passing around the leads.in small amounts. Things are slowly getting worse on the capacitance value of the first cap and it's starting to pass ripple to the intermediate toroid.
Now inductors like DC flow thru, but respond to progressively increasing ripple with progressive heating. As the first cap is ever decreasing in capacitance the inductor is having to take up more of the filtering function, along with that final brown electrolytic filter capacitor
Eventually, that first electrolytic capacitor, that might have been 680 ufd initially, may have declined all the way down to only 10 ufd and is basically out of circuit with that incoming square wave now hammering the inductor and it is responding with more heating up and passing that hammering square wave on to the second electrolytic filter capacitor. Just a short time and the second capacitor goes thru the same heating up and decline of capacitance and the supply voltage just drops out.
Usually in this common failure mode, the power supply just tapers down and drops off and no semiconductors are blown.
This would account for one or possibly two pooched filter capacitors from progressive ramping up of their heating
and capacitance decline and one hot running central / intermediate inductor, just after the first cap dropped in its usable capacitance.
If you have torn down the toroid, a source of like gauge wire could be found at a shop which rewinds electric motors.
Their wire is VERY desirable over otherwise available common insulated magnet wire, as they use the highest temperature rated insulation available.
Or you could get another 1.2 uh toroidal inductor from Farnell / Digi Key / Mousers if you are unable to rework that unit.
Looking at their availability, looks like only one like unit is being stocked anymore . . .at Digi key as a Bourns unit . . . 2000-1R2-V-RC

Da Da Sheet . . .
https://www.digikey.com/product-detail/en/bourns-inc/2000-1R2-V-RC/2000-1R2-V-RC-ND/2534529


73's de Edd
.....
 

Harrison U

Aug 4, 2018
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Don't mean to sound naive but is lower or higher temperature rating on wire for this particular torodial inductor better?
 

davenn

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Don't mean to sound naive but is lower or higher temperature rating on wire for this particular torodial inductor better?

wire like that doesn't have a temperature rating as such

you need enamelled copper wire with the same diameter ... looks to be somewhere around 18 - 20 swg approx.
 

Harrison U

Aug 4, 2018
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Ok, thanks for that, also, I have looked about to see if I could get a cheaper version of the one that 73's de Edd kindly linked, (I can't really justify the shipping costs to my parents :) ) but I haven't found anything even close to 1.2 uH. it is nowhere to be found, is there any chance that 73's de Edd or the website he linked accidentally made a typo?
 

davenn

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Ok, thanks for that, also, I have looked about to see if I could get a cheaper version of the one that 73's de Edd kindly linked, (I can't really justify the shipping costs to my parents :) ) but I haven't found anything even close to 1.2 uH. it is nowhere to be found, is there any chance that 73's de Edd or the website he linked accidentally made a typo?


That is why I have been encouraging you to remake the one you have by getting the appropriate wire
 
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