Questions about salvaged parts - Page 1
Forum section: electronics / beginners

author: Arch
author_rank: Contributor
timestamp: April 08, 2014, 01:31:36 am
content: I took about a printer someone was junking, to see what it's like and what I can get out of it. I have pictures here with a bunch of questions(this is the beginner forum after all):Picture 1:- Near the top left there are little coiled packages. Are they just standard inductors?- Near the top left, there are these little bulb things. What are they? They don't seem to be LEDs, one of them is fairly black on the inside- In the middle, is the square thing a transformer? It's a bit different than the ones I've read about but it seems to match some I see onlinePicture 2:- Laser diode? There are three pins on the back. I think I may wait to play with that until I can be safePicture 3:- Assuming the large part is another transformer- What is the thing on the bottom left? The silver top with black surroundings. There is a side profile picture of it in picture 4Picture 5:- At the bottom left, there are silver resistors. What would these be called? The stripe pattern is different than I am used to- At the bottom right there is a device that appears to have something go in the middle and interrupt the signal. Is there a name for these?Picture 6:- What's the thing on the left labelled as CHG? Is it a standard component or some custom packaging?- The two square wound things on the right look a bit different than the other transformers. Is it safe to assume they are still transformers?Picture 7:- Is it normal to be able to get these kinds of LCDs to work? Or do they tend to have some native encoding/signal that proves tough to figure out? I may try to look up or figure out how to make it work if it's not nearly impossiblePicture 8:- Mid left, what are those two coil things that are placed together? Is this another form of transformer?- There seems to be another big one to the rightPicture 9:- There is a big of darkening on the board under these resistors. What causes this? Heat? Chemicals from manufacturing?

author: Arch
author_rank: Contributor
timestamp: April 08, 2014, 01:35:12 am
content: I am making an assumption that the transformers are of the shell format like in the following pictureI am used to the core type so that's why I didn't recognize them right away

author: Monkeh
author_rank: Super Contributor
timestamp: April 08, 2014, 01:49:16 am
content: Quote from: Arch on April 08, 2014, 01:31:36 amYes, inductors. Possibly just a normal incandescent lamp. Yes, a transformer of some sort.QuoteYep.QuoteYes, transformer. The round component is an inductor (note silkscreen 'L1').QuotePower resistors, 3W or so?, if I'm reading them right, 0.69R. Slotted optical sensor.QuoteDon't know, yes, they're probably transformers.QuoteThe left is a common-mode choke. The large green one is a high frequency transformer. This is the main power supply, everything to the left of that transformer is connected to the mains supply.QuoteJust heat, yes.

author: mariush
author_rank: Super Contributor
timestamp: April 08, 2014, 02:03:22 am
content: picture 1.a) Not sure. Says L on silkscreen which is code for inductor. angle of picture is bad.b) Says D on silkscreen, they're probably some high voltage protection / surge protection / esd protection something as the jacks near that seem to be telephone or fax jacks.c) yes, it's a transformer, but specialty one, most likely again for isolation against telephone lines.You should save those 3 PH1, PH2, PH3 , they're optocouplers. Save the chip with 358 on it, it's most likely a LM358 opamp.The black box with SHINMEI on it is a relay, could be useful for some things. Save it. Save the film capacitor (the big dark orange/red one, save basic capacitors and ceramic ones, save header and connector with wires.2. could be. could also be a simple light sensor to detect tray open or something like that. don't know where you pulled it out from3&4 . Says L near it so it's inductor. Board seems like a small switching power supply though it's a bit too simple (unless there's components on other side as well)5. They're probably used as current sense resistors. Look like 3-5w resistors to me, probably 0.69 ohm 1% tolerance. The chip to the right that has SHINDENGEN on it is probably a motor driver. The caps on the right in the picture look damaged.6. Looks like the high voltage transformer that makes 1000v+ to charge the laser drum and get toner stick to it. CHG = charge ..Yes, those things are transformers, sort of like the ones used in lcd monitors to make high voltage for cfl tubes.7. If you analyze the board to determine what the wires do you may figure it out how to connect to it. The lcd probably has a chip-on-glass on the back which makes the lcd work.Connection should be i2c or spi or parallel along with wires for voltage ground contrast and so on... look under connector, see where wires go etc.Then you may get lucky if you search various sites and check lcd displays with same number of wires in the back. Some controller chips have the same commands so you could find the commands in such a datasheet.8. That's a switching power supply.From left to right you have fuse , x2 capacitors (the dark grey squares), y capacitors or movs (the gray discs things and the blue-green discs) and the common mode choke (the transformer like part) - these work together to filter ac input and prevent the power supply from sending into the socket "noise" ... it's just a filtering system.The red round thing looks like a fuse, so i'm a bit confused why there's two fuses, maybe the glass fuse is for that small white connector at the bottom.Then you have those 4 diodes which convert AC to DC, then it's smoothed out by that round large capacitor, then you have that chip right after the large capacitor which sends pulses of electricity through the green transformer (switching type transformer), basically a square wave is sent.What comes out on other side gets rectified to DC using a chips that have two diodes inside with the cathodes tied together (the two things on the heatsink on the right) and out comes the small voltage on that connector.The resistors in last picture overheated and dried up the pcb and heated it to the point it became brown. It could be because some components on the board went bad (shorted and malfunctioned) or it could be that this power supply was undersized for the printer (maybe they thought the printer would only occasionally print a few pages and then will have time to cool, so it will last past the warranty period)

author: David_AVD
author_rank: Super Contributor
timestamp: April 08, 2014, 02:07:06 am
content: Quote from: Arch on April 08, 2014, 01:31:36 amThose are neon lamps and are sometimes used to clamp spikes on incoming phone lines.

author: Arch
author_rank: Contributor
timestamp: April 09, 2014, 01:40:21 am
content: Cool, lots of info to work fromQuote from: mariush on April 08, 2014, 02:03:22 amMaybe I shouldn't play around with that too much thenFor now at leastQuote from: mariush on April 08, 2014, 02:03:22 amOk, I'll look more in to this. So far, I can see the board pretty much just goes in to a chip that also manages the key pad. On the LCD, there's a little red-ish rectangle that seems to have some tiny lines in the back sideThanks