PLCC socket - Adjusting the contacts
Posted: Mon Dec 24, 2018 11:18 am
I spoke to exxos a couple of weeks back with regards to PLCC sockets, and how that over time the metal fingers that make contact with the chip can lose contact causing all sorts of weird problems.
I'd had 2 machines with odd problems that turned out to be loss of contact within the PLCC socket, so decided to work out a way of adjusting the contacts back to their normal position.
First off I made a tool that comprises just a few odds and ends I had lying around:
1. 2x long header pins, about 15-20 mm long.
2. A slim piece of discarded Veroboard.
3. Some insulation tape.
Firstly, you need to create a small hook at the end of one of the header pins. The hook should be just about the last 2-3 mm of the pin, no more, like below:
And the other pin remains as it is:
You then solder each pin to a slim piece of vero board, then wrap the veroboard in insulating tape. Now you have your tool.
The completed tool is shown here for scale sitting atop the MMU socket of a 520ST.
Here we see the same socket, and it illustrates nicely the sort of problem we're looking to fix.
The bottom row of contacts is clearly not well lined up, and likely to cause poor connectivity between the chip and the socket, leaving us with all kinds of problems.
This is where our tool comes in. Using the hook end, you can carefully hook under the bottom of the finger and gently tease it out ats below.
You must be very careful when doing this, as the fingers don't need much to pull them out, and if you go too far, you'll just need to push then back in again.
The other end of the tool can be used to tweak from the top, by either gently pushing on the fingers, or pushing in from behind the fingers as below.
Again, not much force is needed here to make these adjustments, so take it gently.
Hopefully this will help some of you folks out there who have this problem. It's important to note that you should also really aim to clean the contacts on the chip too before reassembling.
Good luck!
I'd had 2 machines with odd problems that turned out to be loss of contact within the PLCC socket, so decided to work out a way of adjusting the contacts back to their normal position.
First off I made a tool that comprises just a few odds and ends I had lying around:
1. 2x long header pins, about 15-20 mm long.
2. A slim piece of discarded Veroboard.
3. Some insulation tape.
Firstly, you need to create a small hook at the end of one of the header pins. The hook should be just about the last 2-3 mm of the pin, no more, like below:
- hook.jpg (301.44 KiB) Viewed 6680 times
- point.jpg (267.44 KiB) Viewed 6680 times
The completed tool is shown here for scale sitting atop the MMU socket of a 520ST.
- scale.jpg (432.24 KiB) Viewed 6680 times
- socket.jpg (428.73 KiB) Viewed 6680 times
This is where our tool comes in. Using the hook end, you can carefully hook under the bottom of the finger and gently tease it out ats below.
- Tweak_hook.jpg (371.43 KiB) Viewed 6680 times
The other end of the tool can be used to tweak from the top, by either gently pushing on the fingers, or pushing in from behind the fingers as below.
- Tweak_point.jpg (363.13 KiB) Viewed 6680 times
Hopefully this will help some of you folks out there who have this problem. It's important to note that you should also really aim to clean the contacts on the chip too before reassembling.
Good luck!
