-
Categories
-
Platforms
-
Content
Hi - The photo is not real clear but it looks like it may be a diode. The stripe on one end is a clue. The stripe may be the cathode end of a diode or the negative end of an electrolytic capacitor. Electrolytic capacitors are usually larger and a different color. If you have a schematic diagram it would be easier to determine which. Using an ohmmeter may tell you. A capacitor will indicate an open circuit, but since this component is attached to other components it is difficult. Either way, if you can't see any other marks on the component you would be guessing as to the value. Best way is to read the schematic.
davenn
Moderator
I agree ... looks more like a diode
type unknown without more info ... circuit schematic etc
Sir endruw. . . . . . .
Say Whaaaaaaaaat . . . . Do you mean that this is what I would find inside one of those . . . small . . . hardly more than a few cubic inch square SNOW WHITE Apple chargers ; SHOULD a person initially, even be able to NON-DESTRUCTIVELY . . . extract its mini PCB from within?
If you blow / clean off some of the white faery dust from the board, other markings might further show up, BUT I can now readily see the . . . cramped for space . . . placed aside markings of U2 AND D8 which would definitely make your mystery unit a diode.
Now . . . U2 we know as a 3 terminal integrated circuit, in this case a TL431, which we recognize as being an ADJUSTABLE “ zener in a chip”.
NOW . . . . . pull out ye olde DVM and place it in diode test mode function and try its probes across the two terminals of that diode in the charger units, in a no power applied status.
In the testing it should show up as dead shorted----open circuited---- or its forward junction voltage . . .Vf . . . should read out in one of the two test connection modes (Applied test leads polarity swapped.)
By virtue of its close circuit proximity to the TL431 . . . I do not tend to suspect a Zener diode.
Coming back with that good Vf reading should at least confirm if it’s being a conventional diode, with an ~ 600—700 millivolts range OR if it is being down in the 400mv range, you may have a fast switching characteristics unit, OR lastly, a Vf being in the high 100----200’s of mvs, relates to its being a Schottky diode.
( Whoooops I guess that I don’t be having too much smarts . . . as spel chex iz dun tellin’ me now, that it shud bees a SCOTTY diode.. . . . . HAH . . . a lot they noes ! )
At any rate, getting a valid Vf reading should substantiate that it’s basically NOT being a suspect / bad part.
Matter of fact . . . in referring to my provided schematic of the evolution of those Apple units, we can see the same electronics assigned D8 designator even being used there.
Even then, it retained the same D8 assigned designation.
Referring to my provided schematic, YELLOW box, we see Vcc output voltage being basically applied to R13/R28 used as a sampling voltage divider bridge to establish the Zener voltage set up in the TL431.
AND THEN, we also have a like divider set up at R35/R8 to the right, but with a temp sensitive thermistor R35 in the top leg.
In temp sensing, the D8 steering / isolation diode then permits the conducting in / insertion of a correcting voltage to override the other settings initial reference voltage.
TTL431’s drive voltage in the optical isolator to its internal LED modifies the isolated phototransistor for its correction of the other dynamic power supply section of the unit.
Now, tell us your reading of the Vf spec of your boards D8 diode unit.
RELEVANT APPLE CHARGER SCHEMA
73’s De Edd
Say Whaaaaaaaaat . . . . Do you mean that this is what I would find inside one of those . . . small . . . hardly more than a few cubic inch square SNOW WHITE Apple chargers ; SHOULD a person initially, even be able to NON-DESTRUCTIVELY . . . extract its mini PCB from within?
If you blow / clean off some of the white faery dust from the board, other markings might further show up, BUT I can now readily see the . . . cramped for space . . . placed aside markings of U2 AND D8 which would definitely make your mystery unit a diode.
Now . . . U2 we know as a 3 terminal integrated circuit, in this case a TL431, which we recognize as being an ADJUSTABLE “ zener in a chip”.
NOW . . . . . pull out ye olde DVM and place it in diode test mode function and try its probes across the two terminals of that diode in the charger units, in a no power applied status.
In the testing it should show up as dead shorted----open circuited---- or its forward junction voltage . . .Vf . . . should read out in one of the two test connection modes (Applied test leads polarity swapped.)
By virtue of its close circuit proximity to the TL431 . . . I do not tend to suspect a Zener diode.
Coming back with that good Vf reading should at least confirm if it’s being a conventional diode, with an ~ 600—700 millivolts range OR if it is being down in the 400mv range, you may have a fast switching characteristics unit, OR lastly, a Vf being in the high 100----200’s of mvs, relates to its being a Schottky diode.
( Whoooops I guess that I don’t be having too much smarts . . . as spel chex iz dun tellin’ me now, that it shud bees a SCOTTY diode.. . . . . HAH . . . a lot they noes ! )
At any rate, getting a valid Vf reading should substantiate that it’s basically NOT being a suspect / bad part.
Matter of fact . . . in referring to my provided schematic of the evolution of those Apple units, we can see the same electronics assigned D8 designator even being used there.
Even then, it retained the same D8 assigned designation.
Referring to my provided schematic, YELLOW box, we see Vcc output voltage being basically applied to R13/R28 used as a sampling voltage divider bridge to establish the Zener voltage set up in the TL431.
AND THEN, we also have a like divider set up at R35/R8 to the right, but with a temp sensitive thermistor R35 in the top leg.
In temp sensing, the D8 steering / isolation diode then permits the conducting in / insertion of a correcting voltage to override the other settings initial reference voltage.
TTL431’s drive voltage in the optical isolator to its internal LED modifies the isolated phototransistor for its correction of the other dynamic power supply section of the unit.
Now, tell us your reading of the Vf spec of your boards D8 diode unit.
RELEVANT APPLE CHARGER SCHEMA
73’s De Edd
Last edited by a moderator:
I do NOT think that it is a Zener diode.
If even the tiniest bit of metal is left of the original leads, that would let you touch a test probe tip to them.
And you can use the sharp corner of a single edged razor blade , or the tip of a # 11 X-Acto knife to dig out plastic to then re-access to an internal lead, having been snapped off.
Of our universally used / dirt common . . . . and cheeeeeeeap diodes, it is probably right at the specifications of a 1N4148 or 1N914 commonly used diode, but needing infinitely less current pass through, than the mammoth specifications of a 1N4007.
73's de Edd
If even the tiniest bit of metal is left of the original leads, that would let you touch a test probe tip to them.
And you can use the sharp corner of a single edged razor blade , or the tip of a # 11 X-Acto knife to dig out plastic to then re-access to an internal lead, having been snapped off.
Of our universally used / dirt common . . . . and cheeeeeeeap diodes, it is probably right at the specifications of a 1N4148 or 1N914 commonly used diode, but needing infinitely less current pass through, than the mammoth specifications of a 1N4007.
73's de Edd
Last edited by a moderator:
Sir endruw. . . . . . .
Oui . . . . . . .exactly
Once that boo-boo is corrected, then there is the units REAL problem still left.
73’s De Edd
Oui . . . . . . .exactly
Once that boo-boo is corrected, then there is the units REAL problem still left.
73’s De Edd
Last edited:
I attached photos how did i disassambled the iphone 3 charger,i did'nt harmed it's case i made a very beautiful work .But i can't recognize what the 4 smd resistor's value (i circled it with red) and i replaced the diode (blue circle) but i don't know is it 1N4148 or 1N914. It's not wokring when i plug it to 220v .And thank you for all previous reply. 
That's the problem ,i only can recognize one ,because 3-4 parts destroyed in the charger the diode is ovious because it has a tiny hole ont it ,but i don't sure about the resistors 3 of the is left smoke on the inner side of the case ,but i know the resistors can endure lot of heat and maybe they are not damaged only overheated ,or they lose some resistance from they original resistance and i can't read the numbers on them beacuse it's lost it when they overheated.Can you recognize the resistros value from the schematic?
73's de Edd Do you think it's an 1N914 diode what i replaced?(blue circled on my previous post)
Similar threads
