Non-standard 68-pin PLCC socket?

[TTL]

In order to replace a damaged 68-pin PLCC (through PCB hole) socket on a computer's PCB I ordered a new one through eBay and much to my surprise I found the distance between the pin rows to be different! The pin spacing however seems to be the same. Are there multiple standards here, or have I come across non-standard sockets somehow?

 

[TTL]

By the way, the socket I purchased is a 3M model 8468. I've compared this datasheet (below) with other 68 pin PLCC sockets but haven't been able to find any with the larger dimensions I need.

 

[(*steve*)]

The pin spacing however seems to be the same.

The pin spacing MUST be different or the measurements you're seeing would also be the same -- unless you've miscounted the pins.

I can't imagine that someone would build a custom socket to prevent you from replacing it (it's a pretty gnarly thing to remove) but I also don't know why anyone would deviate from normal pin spacing.

 

[TTL]

I agree and also found that strange.
I'll recount the pins, but there should be 68 of them (it's for a Motorola MC-68000 16/32 bit processor). I'll also measure the pin spacing again.

 

[TTL]

OK, I've taken a closer look and can confirm that the PCB needs a 68 pin through-hole PLCC socket with 0.1" spacing between the pins. But the row spacing is indeed different when comparing the socket with the PCB holes:

Row spacing on PCB is clearly wider than on the PLCC socket.

PCB row spacing is shown to be approx 23mm (inner) and 28mm (outer).

Replacement socket shows row spacing to be approx 25mm (2.54cm or 1" perhaps? -inner) and 28mm (outer).

The pin to pin spacing however is the same (I tried inserting a row).

PCB next to socket.

The final photo above reveals something interesting.... the pin count is both 68, but the pin layout is different!
Making a custom socket for a standard component sounds weird though