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Electronics => Repair => Topic started by: Mamejay on January 31, 2017, 05:37:59 am

Title: 68 Pin PLCC Socket required for reverse connection. Help..
Post by: Mamejay on January 31, 2017, 05:37:59 am
Hello everyone,
Not sure if you can help but I am repairing an accelerator board for an Amiga computer.
The board clips onto the SMD 68000 CPU.  The board I have had a damaged PLCC connector.  I ordered a replacement from China but when it arrived I found that it would not clip on like the original one.  The connector is a through hole.
Looks like there would be a particular type that is required.  I have asked around in the Amiga community but not getting any joy.
Attached is a picture of an existing board I have and also a stock photo of the accelerator connected to the computer.
Hope someone can help.
Thanks
Title: Re: 68 Pin PLCC Socket required for reverse connection. Help..
Post by: Ian.M on January 31, 2017, 06:13:35 am
Did you google the 3M part number?  Well Gain Electronics, USA, claim to have stock.
Title: Re: 68 Pin PLCC Socket required for reverse connection. Help..
Post by: Mamejay on January 31, 2017, 06:28:42 am
Yeah I did but it looks different to this one.   Also when ordering 2 the shipping cost cane up as $105usd
Title: Re: 68 Pin PLCC Socket required for reverse connection. Help..
Post by: sleemanj on January 31, 2017, 07:00:17 am
Maybe ask those guys who make that crazy fpga accel i think they use the same piggyback sort of deal

http://www.apollo-accelerators.com/ (http://www.apollo-accelerators.com/)
Title: Re: 68 Pin PLCC Socket required for reverse connection. Help..
Post by: Mamejay on January 31, 2017, 07:54:21 am
Maybe ask those guys who make that crazy fpga accel i think they use the same piggyback sort of deal

http://www.apollo-accelerators.com/ (http://www.apollo-accelerators.com/)
Already emailed them and also the company that makes the one I am trying to repair. 
Title: Re: 68 Pin PLCC Socket required for reverse connection. Help..
Post by: Moshly on January 31, 2017, 08:01:11 am
Hi, all I can find on that pat number is that it is just a standard socket.
It is available here -> https://wellgainelectronics.com/1397_3m (https://wellgainelectronics.com/1397_3m)

From what I have seen, they are just normal sockets that have had the top edge sanded down to the top of the pins. Also they have had a cut-out made in the shell to slip over a SMD cap on the mainboard.
Some sockets may also need some plastic removed from the inside flat area so the socket sits flat on the chip.

I have one of these and have found the whole arrangement very susceptible to poor connections.
I found that it makes a better fit if you use desolder braid on the edge of the CPU pins to remove all the solder that may have wicked up during the original soldering process. (clean pins thoroughly with PCB cleaner)

When installing the board, take the main PCB out of the case and press both together to make the best fit (with it in the case the PCB bends and it will never go together properly.)
Then (pressing on the center of the socket) grab the right side of the ACA620 PCB and move it slightly (parallel to the main board) towards the keyboard connector, jiggle it back and forth a few times (this will seat all the pins that may not have a good grip on the chip) Now test the system, if all good bolt it down using the supplied mounting hardware and re-install into the case.

Note: these things cook at ~70c if not cooled, add a small 5V fan (take pwr from the crystal) see pic