When I was shopping for some goodies at All Electronics I came across a circuit card they were selling for $1. The description indicated that the board included two voltage regulators, a crystal and assorted parts. I like to scrounge and look up the parts used in consumer electronics so I purchased one of these just to scrounge. It’s like a grab bag of parts that engineers really use…
In this short article I provide some high-resolution pictures of the board using the PCB scanning method described in this previous article. I remove parts using the scrounging methods described here, and I list the parts I thought were worth removing, with data sheet links.
This picture shows the component side of the board. There are several interesting IC’s and transistors to scrounge. Notice the two voltage regulators that are bent over in the middle right of the picture, just above them is what looks like transformer. This is actually a large inductor which I am sure will come in handy on a future project.
Since this board was part of a multi-disk CD player I expected to find some motor driver ICs. There were two of these ICs, one large power transistor, and several smaller signal transistors on the component side of the board.
Although there were a lot of aluminum electrolytic capacitors I only removed the largest one. These are fairly cheap to purchase so I skipped over them. The short legs would have made them difficult to re-use anyway.
The board also had some PCB-mount pushbutton switches and four 20K potentiometers (pots) which were very much worth the effort to remove. I noticed two through-hole parts as well. One was an Atmel serial EEPROM and the other was a neat dual motor driver IC.
The solder side of this board has a large number of surface mount components. The resistors are marked with values so they are easily reusable. For the caps you would need to use a capacitance meter. These parts are glued on so it takes slightly more effort to remove them. I used a hot air embossing tool to heat the board and a pair of small tweezers to wiggle the parts off.
I only took the large tantalum cap and the surface mount transistors from this side of the board.
To do the scrounging job I used the tools pictured here. Yes I really do wear safety glasses when I do this work. Please take care of your eyes, it only takes one accident to lose an eye and this is dangerous work. Read all the information on my scrounging pages here and anything else you can find before you start.
I actually used two pairs of pliers: one to hold the part and one to hold the PCB while it was heated. A soldering iron and solder wick were used to remove the regulators but it was so much easier to heat the board up and pull the parts with the hot air gun that I soon dropped the solder wick method. A small pair of tweezers were used for the surface mount ICs and parts. Heating the area with the heat gun then removing the parts with the tweezers was fairly easy. Larger parts, like the connectors and POTs required a pair of long nose pliers.
Scrounging this board was fun and definitely worth the effort. I picked up some new lab stock and learned a bit about CD players in the process. Here is what I collected.
|1||Large inductor (looks like a transformer)|
|4||PCB pots, 20K|
|1||4.7uF SMT Tantalum Cap|
|1||4.19MHz Ceramic Resonator|
|1||1000uF 16V Aluminum Electrolytic Cap|
|Many||Smaller Aluminum Electrolytic Caps|
|1||8-Pin DIN connector|
|1||Leaded power diode|
|1||Leaded 2.2 Ohm 1W resistor|
|1||SIP connectors and mating cable with PCB termination|
|1||7805A TO-220 5V Linear Regulator|
|1||7808A TO-220 8V Linear Regulator|
|1||TO-220 NPN Power Transistor with Beta of about 150|
|1||TO-92 NPN Transistor with beta of about 50|
|1||Small (TO-92 like) NPN Transistor with beta of about 150|
|14||SMT Transistors or diodes|
|1||Thermistor with negative coefficient (not sure)|
|1||Atmel 92C46 in 8-Pin Dip – 1K-Bit Serial EEProm http://octopart.com/search?q=93C46|
|1||LB1649 – Dual Bidirectional Motor Driver http://octopart.com/info/Sanyo/LB1649
|1||JRC 2100 – Unknown 8-Pin SOIC|
|1||A393F – 8Pin SOIC Dual Comparator from KEC http://www.alldatasheet.com/datasheet-pdf/pdf/69356/KEC/KIA393F.html|
|1||SM5871AS – Digital audio Sigma Delta D/A Converter http://www.datasheetarchive.com/preview/3109761.html|
|1||KA9258D – 4-Channel Motor Driver – designed to do many functions in a CD ROM drive related to head focus control. http://www.datasheetcatalog.org/datasheet/fairchild/KA9258D.pdf|
|1||KA9201 RF AMP for CD Player. Handles the optical sensor that reads a CD. http://www.datasheetcatalog.org/datasheet/SamsungElectronic/mXvuyqz.pdf|
|1||KA8309B Servo Signal Processor for CD Player. http://www.datasheetcatalog.org/datasheet/SamsungElectronic/mXvuyru.pdf|
|1||AKD-77CW N45 – Unknown|
|1||KS9210 – Digital Signal Processor – Designed specifically for CD Players http://www.datasheetcatalog.org/datasheet/SamsungElectronic/mXtzvxq.pdf|
Looking up the parts
I found most of the parts without much trouble but there were these two I could not find any information on. See if you can find anything. They are shown below, hopefully you can read the part data from the scans.
Can you find a data sheet for these two mystery parts?
Have a good source for data sheets online? I normally use Octopart but for these special parts I end up with a lot of sites that try to get you to register, only to find out they don’t even have the part data sheet you were looking for.
Any other articles about scrounging parts form PCBs?
Wouldn’t be neat if there was a database of parts that located them in electronics that we could scrounge. Enter a part you are looking for and get a list of the common devices that include one. Or maybe enter in the device you are about to toss to see what interesting parts might be inside. There could even be a recycling Craig’s List kind of thing where people that were looking for specific parts could connect with people that were throwing away stuff that had those parts.