Oolite Bulletins

Taking apart defunct electronics components such as MP3 players (not very gratifying) and my ancient MPS803 dot-matrix printer.
Got almost all components tracked and determined...only several parts are mysterious unmarked lumps of resin... sush as the yellow blob PTH linked to a Q10...I think transistor?

Anybody else ever got into disecting an old, loved appliance?

Once I made a working electric iron out of three broken ones... Does it count?

Dissecting? Oh yes, often. Ressecting them is the tricky part. ;-)

Although I did recently mend my telephone, after remembering that I do in fact own a soldering iron.

my iron is a bit worse for wear...the ....important bit has corroded to such an extent, that I cannot replace it anymore.

Planning on recombining the components into something less functional but more entertaining than outdated/defective equipment.

Likely to end up in a pile of discreet components rusing away in some bins...but what fun we have in the meantime.

Ideally I will remember those classes on electronics engineering and logical circuits...'ts been almost ten years I last tried to understand capacitor/resistor networks, not counting a wheatstone bridge (?) for some project I can't half recall.

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Aside from a few ICs a bunch of capacitors, a load of resistors and some diodes and ZenerDiodes the printer also yields several steppermotors and some switches. One LED and some esotheric components. Even the mechanical components may be usefull in time.
The printerhead is too specialized to be usefull.

anyone know what a (circuitboard code)DB (SIRBA)is meant to be?
It has 4 legs, 2 are marked ~ one OO and one +.
Maybe a timer or counter?

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So I'm looking forward to dissecting my old Nokia NPE3NX 168 when I get some bloke to rip out the SIM-lock on a newer phone I acquired from a friend.
There should be a nice motor in there for the vibrating mode.
...Ill need 6 sided starshaped screwdrivers....let's see if I got those...

anyone know what a (circuitboard code)DB (SIRBA)is meant to be?
It has 4 legs, 2 are marked ~ one OO and one +.

Diode bridge, I'd guess from the description, AC --> DC

Darn it's hard to find datasheets on old components!

>:#

small fact: at least 3 versions of philishave electric razors have exactly identical circuit layouts. (based on the 2 I dismantled myself and a french guy with another version who was looking for the same datasheets on a forum.)
Of which I cannot find datasheets on the IC (TEA1019) I think it's a switch as the only reason for this stuff is to safely apply 220V to power a small electromotor ....which oddly has a small capacitor tacked to the +pole/casing. maybe I'm misinterpreting that component and its functioning as a fuse...

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OK nice I dug up an old MS mouse. there should be some nice light emitter/sensitive diodes in there and switches.

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I'll have to drill out the old soldering bit from my soldering iron. nasty job.

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You could be right on the Diode Bridge,
I couldnt see it first, but the OO symbol is actually 2 diodes facing eachother.

I took my car to pieces but that's another story...

The problem with electonic things is that everything tends to be surface mounted so it's too small to use for anything or it's big but too specialised to be useful.

I've repaired monitors with dry joints but never taken something to pieces for the purpose of saving the components for some other project.

More common is dismantling something to see if it's repairable and then seeing that since the expensive bit has died it'll be easiest to just buy a whole new whatever it is. Eg electric shower (the heater itself) or washing machine (the pump).

On the other hand dyson hoovers are very satisfying to disassemble clean up and rebuild as they're so obviously designed to be serviced rather than thrown away.

If you're looking for torx screwdrivers (as my dyson needed) then Maplin are doing a special christmas offer where a set of 10 (or so) of them comes with a free screwdriver and 2 dozen interchangeable heads.

I already have two sets of srew-bits the trouble usualy is that the screw is recessed so much as that bits cannot reach.

I know what you mean, while looking for specs of some sort I found the IC switch component (TEA1019) in the shaves cost more than 50(i think it was pounds-eng) lol
Yr also on the money for SMCs, those destructed MP3players are useless, except for use as techno jewelry.

Anoying is: the way the pins of through-hole mounted components are bent , then soldered.
Now I have to melt, bend while molten then repeat for the other legs, then melt again and push/pull them out.
't will keep me off the street for a while.

Currently trying to wrangle the old vacuumcleaner for a dissection.... mwahahaha!
Although the components in that may be a bit over powered.

Well I am a self employed PCB (printed circuit board) assembler so I see them ready-disected lol

Pliers.

A disassemblers' best friend.

Ended up demolishing board risking flying chunks of BCB in lieu of solderburns on my fingers.

AND: Cool. what do you assemble in the time you are working for #1?

Arexack_Heretic wrote:

what do you assemble in the time you are working for #1?

I get work from a local company that sells all sorts of lighting units.
At present I have 5000 security light boards to make up. They are the sort of lights that have a motion sensor that turns the light on whenever someone walks past.

not very glamorous then

Still, self employment sounds good.

god, I hate those things (esp. when they are connected to those 500W floodlights).

I have the guts of about 20-odd Z80 based cash registers that we were getting rid of at work. More 74* series logic than you can shake a stick at, lots of 128K static RAM etc.

The best tool for disassembly is my B&Q paint stripping gun. Clamp the PCB you want to strip, start up the heat gun at high power, and when the solder melts, simply remove all the chips with a pair of pliers.

Surface mount is actually much easier, since the pins don't tend to get hung up in the holes. They just fall off the PCB if you heat it, hold it upside down, and just encourage the chip slightly with a small screwdriver.

SMD (surface mount devices) can be hand soldered without too much trouble. Here is a home-made PCB with a chip (USB FIFO) that is in a surface mount SSOP (small shrink outline package) with 0.5mm pitch pins, which I hand soldered:

http://www.alioth.net/Projects/USB-Brea ... akout.html

Here's an ethernet board I made for the W5100 ethernet chip, connected to a homebrew Z80 based computer. I made this about a month ago. The W5100 chip is an 80 pin package (20 pins a side) - 20 pins crammed into 8mm - so a 0.4mm pin pitch. My PCB design rules are actually finer than some PCB factories to make this board. I hand soldered this, too:

http://www.alioth.net/tmp/w5100-online.jpg

The hardest part was getting the chip lined up on the pads (you get one side lined up, another side is slightly out, so you nudge the chip, and some other side then goes slightly mis-aligned!) Once it was aligned, soldering it wasn't too hard. (The continuity/short testing took longer than the soldering!)

Next job is to make my own reflow soldering oven (repurpose a toaster oven - a decent toaster oven can actually meet the reflow profiles)...

wew

those little legs look like hell to solder.
you solder up the legs, line it up and then reheat?

these pcb's from a kit or made to order?

have fun with those registers.
You able to retrieve usefull information on the chips used?
I contstantly find that datasheets are unavailable or the components are unknown altogether.

The chips in the cash registers are all common parts, 74HC* logic (which is still made in vast quantities, the NXP website has datasheets for all of them - http://www.standardics.nxp.com/ ). For all the other stuff (ADCs, DACs, PIO etc), Datasheetarchive.com has them all (most is still in production, too - the ADCs and DACs used are actually quite expensive items - about 4 quid a chip so it's handy to have this free supply!)

Most of my PCBs are home made (I did get Olimex to make a couple for the Z80 computer because these are very time consuming to make, having almost 500 holes to drill). I use this software - http://pcb.sourceforge.net/ - to create the PCB layouts. Then print the layout to matte "inkjet photo paper" in a laser printer, then iron the layout onto copper clad board (with a clothes iron) and chemically etch. The laser printer toner gets transferred by the hot iron from the paper to the copper clad board, and acts as etch resist. The etchant removes the copper which isn't covered by toner.

The pins on fine pitch surface mount devices - basically, under a magnifying glass, I get the chip sitting correctly on all its PCB pads and then carefully tack down two pins at opposite corners with solder so it doesn't move, and check for alignment again. If it looks good, then I "drag solder" the rest of the pins - basically, get a blob of solder on the soldering iron tip, and drag it down the device's pins. The solder wants to flow over the fluxed pins and pads, and since the pins and pads are so small they heat up really fast, so the solder just flows out of the blob onto the pins and pads. Since the gap between pins is only 0.2mm, most of them end up getting a solder bridge, so the final step is to wick away the excess solder with solder braid. Then check for shorts and continuity, and re-apply solder braid where any shorts are found, and re-work any opens with a blob of solder/reapplication of wick.

Lining the chip up at the start, and testing the solder joints is the longest part of the process.