Blizzard Turbo Memory - SMD memory chips doesn't work
 

Hi!

I have Blizzard Turbo Memory with 2MB attached memory in 4 TC514400 chips. Those chips in DIP package are almost impossible to find, so i tried to made soj20/26 adapter for those SMD ones that can be found on old simms. But the thing is, it is not working. According to datasheet SMD 514400 chips are pin-to-pin compatible with those in DIP package. Or maybe am i wrong?
Blizzard memory test tool marks those chips as BAD. I checked for shorts or connections in socket but it's ok. I don't know what is going on. I didn't change any settings, just pull out DIP ones and replace with new SMD ones, tried to even mix DIP with SMD, but SMD ones was always marked as BAD. Is there something i don't know? Is there somebody who have original TC514400P chips in DIP package or something that could work?

From the datasheet the pins have exactly the same pin-out.

Care about the speed on the modules and try to not fry the chips when taking they out from the SIMM board.

Those chips are 70ns, same as the ones on the board. I tried 5 chips and no one works, maybe i'll try other chips later. I used a heater (used to remove paint) to desolder chips, i blow with hot air to the back surface until chips just fall. Is that why they could be damaged? I ised that method to desolder 2MB chips from 72pin sims and in most cases time they work fine. I dont have expensive soldering stuff so i have to stick with something cheaper like heater :)

Surface mount devices are designed to go through an oven which is set up for the board that they occupy to travel through at a speed and temperature that suits the product and does not overheat the devices and stays within the maximum heat and time periods that a device can withstand while still melting the solder paste. When using a proper de-soldering/removal unit like a Danotherm hot air station, heat is blown directly onto the legs and pads of the device for a short time and then picked up with the vacuum head. The time depends on the device and ground plane etc transferring heat away etc.

Your method may work better if you look at the tracks and pads that are on the board that you have already removed a chip from and see if there is any way to cut the tracks close to the actual pads so that there is less copper to disperse the heat and hopefully make the chip removal that much faster. Apart from the thermal shock damage there could be physical/mechanical shock or maybe your antistatic wristband has broke (it happens).

Good luck with your project :)

I finally managed to made it work, actually only two chips were damaged and they affected whole memory controller so blizzard memory testing software was thinking that all of them are bad. Now it's working fine. There is a gerber file of that adapter in attachment if somebody want actually to do same as me. Pins for the pcb are just DIP20 socket soldered upside down and cut out.

I made a re-run of these boards, if somebody wants some, please respond via amibay.