Unfortunately there is no Schematic or Boardview for 820-00292 ... but 820-00291 is very similar and the placements of the components in that area are practically the same ... therefore the values will be too ... looks like it's the GPU that might be the difference between them ... From the 820-00291 Schematic: C4500 = 0.1uF (100nF) ... your measurement was good for this value C4501 = 0.1uF (100nF) ... and also for this value R4400 = 100K (the missing ripped off component) - is a pull down resistor .
Man that is a self resettable fuse that as maximum break current but it also acts as variable resistor at certain current range, when they break that must be very high current. example : It could start increasing resistance after 5A but at 15A it will blow. The exact value is design to protect, but also to limit. When this fuse blow it must be something very wrong in the circuit.
15A to blow........ you can't be serious. Your house basically goes on fire before fuse blows. Amps will never go that high unless there is a short. Where did you get this information??
@@jonnyheart303 house is high voltage if you calculate power is way above. Btw I t's an example. Download any polyfuse datasheet and read it you probably learn something.
SInce the missing caps were on data lines was the fuse shorted out when those data lines were shorted ? Just wondering what caused the fuse to blow since the caps are on data lines rather than voltage lines. Also how can you be sure that fuse is the same rating as the blown one?
Fuse likely blew when customer removed screen without disconnecting power. caps probably got knocked off by mishandling the board. Fuse is common 603 3A.
@@dorfschmidt4833 It's 3A Fast blow www.mouser.com/datasheet/2/240/Littelfuse_Fuse_494_Datasheet.pdf-1317338.pdf. How did you come up with 2A. Just wondering.
603 0 ohm Resistor is perfectly OK and has a lower amp rating then original fuse which makes it safe to use. Fuse is nothing but a line that is made to break when there's a sudden surge that exceeds the rating of the fuse. My experience is, a fuse will never break on an iMac unless screen is being tempered with while machine has power, or liquid damaged which is very unlikely on iMacs.
I thought you measured the data line caps in circuit to get the capacitance rating and then was going to measure the newly installed ones in circuit for comparison?
Excellent videos have learned a lot. And was wondering what microscope do you suggest for been able to work with smd starting out here. Any advice would be highly appreciated. In advance thanks.
i have an Imac 27 5k retina late 2015 that it does not turn on at all. i open it and i saw that none of the leds are lighting despite the power mains is ok, and the 12 v are ok. what can be the problem? is there any other voltage coming out from the power supply? to see that just 12 volts are ok is enough to say that PS is working?
You might have an idea for me? I checked my RAM battery, it's full. If I put an external HD I have the normal screen: gray with apple logo. I tried to reinstall the OS due to all the trouble and startet up in "choose" HD mode. So the screen is fine, I can see all I connected. But when I disconnect the external HD and start up, the startup is normal till the chime but the screen stays black. I tried recovery mode and left him like an hour, he asked me to put in my pasword to continue. But whatever I do, the screen keeps black. It's like he is going into sleep mode and does not to want to wake up. I can hear him turning off to sleeping mode and that's it, dark screen. Thanks if you have an idea. 🤷♀️
