[sdiy] MF4CN filter /YMF262/YAC512 chip uses

[anthony]

I have removed these very chips from an old Compaq motherboard. This is what 
I do:

1: Desolder the bulk of the solder with a desoldering iron from Radio Shack. 
I haven't found an inexpensive built by any other manufacturer and the RS 
unit's quality has been steadilly declining. That said, it is imperative 
that you use a relatively new tip and that all openings are relatively 
unobstructed (I find that these units give the best service when rigorously 
mainainted - which usually involves removing the bulb and jamming debris out 
the tip end with the tip removed and the iron hot). The more solder you 
remove here the easier the next step is.

2: Place a strip of Radio Shack desoldering braid over the leads. Touch each 
pin through the braid, held with a tweezer, with a very hot iron - at least 
25, but better 30 maybe even 40 watts - a chisel tip is best. The point is 
to get the joint hot very fast without overheating the bulk of the chip. 
This may require several passes. Take your time and don't let the body of 
the chip get too hot.

2.5: Often these chips were glued in before soldering so it can help to heat 
the back of the board under the chip to soften the glue.

3: This is the tricky part. When it appears that you have soaked up all of 
the visible solder with the braid, gently pry at the edge of the chip with a 
flat screwdriver. Use a light pressure. If it doesn't pop up, don't force 
it, but quickly touch the pins closest to the screwdriver with the very hot 
iron. Sometimes the momentum when the first few pins come loose can cause a 
sticky pin to break, but if you use gentle but firm pressure this should not 
happen.

I have successfully desoldered hundreds of chips using this technique and 
have broken relatively few chips. Being in a hurry is the usual cause for 
disaster. And I have indeed lost some very desirable chips in haste.

If it seems like I've left anything out, let me know.


enjoy,
Anthony


> The Yamaha chips are used by:
> http://www.ucapps.de/mbhp_opl3.html
>
> If you have a good way to get them off the pcb I'd be interested to
> hear it.  I have one lying around waiting for the Yamaha chips
> to be pulled off...
>
>
>> Does anybody have any suggestions whether these devices are usable for 
>> SDIY.
>> I am prepared to yank them from an old Aztech soundcard after surfin' up 
>> their datasheets and was hoping to put them to use.
>>
>> http://cache.national.com/ds/MF/MF4.pdf
>> http://www.labmaster.com/surplus/parts/html/ymf262/ymf262.pdf
>> http://www.labmaster.com/surplus/parts/html/yac512/yac512.pdf
>
>