THE PLL MOD GUIDE

Updated 05/11/02 by Tim B @ OCWorkbench.com

Original thread - highly recommended read.
http://www.ocworkbench.com/ocwbcgi/ultimatebb.cgi?ubb=get_topic&f=27&t=001272

ICS9248-199 Datasheet Courtesy of Miikka Kolo

More pics here > http://www.saunalahti.fi/~kolo/hardware/K7S5A

By Pegelius

See this Wiring guide pic

Ok, here is some information conserning building this kind of mod. My english isn't, in most cases, perfect, so ask if something bothers =). Note: some knowledge IS required.With this mod you have to solder your mobo. So be warned...
and i'm not responsible if you blow up earth and brake your computer =). I'm just telling how to...
well, sort of. And this information originally is from one Finnish-O/C-guru who got it from Japanese clockers...

copy-paste of mail i send to Easychiller:

Ok, i'll try to give some information:

I used pll-chip from a 486 machine. U should use more advanced chip, if u want to have serial I/O and USB working (feed for 24 Mhz and 48 Mhz). Modern mobos have those, so broken mobo is good.

First you find the pll-chip. It's near crystal. Most of the time manufacturer is called ICS or Cypress. Datasheets can be found from their websites ( www.icst.com and www.cypress.com ).

If you don't find datasheets, find another mobo (with different chip) :/.

Next comes the fun part, u get to brake things .
U need to get the pll-chip out of the mobo with piece of the mobo. So you saw (or use a dremel) and cut about 5x5cm piece off of the mobo in a way that the pll-chips is in the middle. Be carefull to not to brake the chip. This piece is called your Turbo-PLL.

Things to get:

-some wire
-3x 50-100 ohm resistor (so you won't burn anything with missconnections, well atleast not so much... .
-crystals for testing, ~13- 20 Mhz, more you get, more FSBs will be available.
-also the datasheet for K7S5A's pll's datasheet, can be found from
ICS , model was sumthing like : 9248-199 tms.

Next you have solder wires with resistor to TurboPLL's REF0, 24 output and 48 output. Find also VDD and GND. There goes power to the chip.

Next thing is to find correct spots in the K7S5A where to connect those replacing signals. It is done by testing the continuity with voltage meter or something which shows if two spots are connected. REF0 (14.3)Mhz) leads to two resistor; other is pulldown (REF0 also works as input during boot), and other is the one to be removed (around 33 ohm). When removed, connect REF0 from Turbo to other spot where resistor was (the further one). 24 works same way, to resistors, othe pulldown (i guess, didn't measure thoroughly because didn't have those replacing signals in my Turbo). 48 is only output, so finding the resistor should be easy.

Happy modding, ask if something bothers.

PP