PLCC SOCKETS ARE EVIL

[exxos]

I got the 3M sockets....


This image is with the chip place on top of the socket (not fully inserted)

3m1.jpg

This image is with the chip inserted....

3m2.jpg

And this is trying to get a close-up shot....

3m3.jpg

It is difficult to get the pins and the plastic parts in focus at the same time...

The angle of everything makes it look worse than it actually is... Basically the plastic spacers go in between the PLCC pins are small enough to bend the pins, and they all look perfectly aligned... In actual fact, the plastic spaces do not even seem long enough to even be a problem..


Other sides of the socket also seems good on the actual electrical contacts... All the contacts look pressed together perfectly, which is of course how they are supposed to be... Some of the other sockets there was a clear visible gap is why I have had so much trouble with them.

I have only just started using the socket, but so far it seems to be best fitting socket I have seen so far..

[Maeke]

I'm half expecting someone to make a printable compatible atari plcc68 socket at this rate. :threadjacked:

[exxos]

PLCC SOCKETS ARE EVIL - THE NEXT CHAPTER.

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Been testing mc68882 FPU'S in my Falcon DFB1X for some time. Though I noticed I seem to be getting more than expected failures all of a sudden.

I had swapped some known working chips back into my ZIF adapter socket and they were constantly failing also :roll:

My first point of call was to clean the contacts on the chips with IPA. Made no odds.
Re-seated the adapter several times. Made no odds.
When round the contacts of the ZIF sockets with contact cleaner and a cotton bud. Made no odds.
Re-solder the entire adapter, at least the pins I could actually get out. Made no odds.
Soaked the ZIF adapter in IPA. Made no odds.
Cleaned the SMT PLCC socket on the DFB1X. Made no odds.
Tried the known good FPUs direct in the DFB1X socket. Several worked fine!
Put back the ZIF adapter - still failing.
Went around the SMT socket with a bent pin to pull out the contacts a bit more. Made no odds.
Sprayed the SMT socket with contact cleaner and went around with cotton bud. Made no odds.
Bent the pins out again even more. Made no odds.
Continuity check the entire adapter.. Everything was fine.

Checked under a magnifier on all the connections and contacts and could not see anything wrong.
In the end I basically concluded my adapter had become faulty somewhere not obvious.

So spent about half an hour looking for my spare PCBs and thankfully I had a new ZIF socket in my parts box. So I then spent over an hour building up another board which are incredibly annoying to build up! :lol: :roll: I thought it had to be something broken on the adapter as I could not find any failure with the FPU in the DFB1X directly even after smacking it all around a bit.

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So then what happens.....MADE NO FEKING DIFFERENCE !!!! :pullhair: :pullhair: :pullhair: :cussing: :cussing: :cussing:

After a couple of hours head scratching and I basically run out of ideas.

I then had a random thought of just trying to lift up the FPU in the socket a little bit as I have had similar issues before.. and that always helped.

A bit hard to see but the black plastic is there and not very thick either...

IMG_3565.JPG

Lo and behold it then started working perfectly !!!!!

I have even checked the contacts from the FPU pins under magnifiers and it looks fine. Not before when it was clearly visible one the normal PLCC sockets that there was a gap causing contact problems. But it basically looks fine with the ZIF socket.

I'm still rather perplexed , but it has solved the problem and clearly there is something "wrong" with even ZIF PLCC sockets now ! :roll:

:dizzy: :mad:

[Badwolf]

One of my HN27C4096s only works in the 'deep' ROM switcher socket in my STE if I *just* lift one corner a bit!

Definitely solid. :?

BW

[exxos]

One of my HN27C4096s only works in the 'deep' ROM switcher socket in my STE if I *just* lift one corner a bit!

Yeah I've had to that with stuff as well. Everything just seems so rubbish these days :roll:

Its mostly why I moved to only using 3M sockets in the end. I went past caring how much the things cost.. I just wanted stuff to work!