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auberon
25th November 2015, 22:39
Hi all,

FINALLY, I sadly accepted the fact I'll neither find a 8372B to revive my A3000, nor a plug-in 2MB Chipram expansion (Mini Megi) for my A2000...I'm simply 20 years too late for digging something up! :)

Now I'm planning to do this (probably well-known) "2 MB Chipram Mod", which utilizes a 8375. I know it's not a 1:1 replacement due to pinout differences, so I'd like to make a small PCB, with a PLCC socket on top for Agnus, and the corresponding PLCC "counterpart" on the bottom side, which will fit into Agnus' original Mobo socket. (The "Mini Megi", for example, provides this plug-in socket.)

So, gentlemen, the big question is, what's the correct technical term for this PLCC "counterpart"? I searched eBay with every possible (I think) term, but to no avail -- all I get is hits for "standard" PLCC sockets. If someone could bring some light here, I'd highly appreciate that. Pointing me to a shop or seller would be even better!

The perfect solution, of course, would be a Mini Megi, that somebody's willing to sale... ;)

Thanks in advance

Auberon

demolition
26th November 2015, 09:16
You could drill a large hole through another Agnus or similarly sized PLCC IC which will disconnect all the pins, glue it to the bottom of your PCB and solder small wires from the top of each pin to your PCB. Not the most simple, but it could be done. :)

Bryce
26th November 2015, 10:01
They're called PLCC84 Male adapters, but they don't come cheap...

http://uk.rs-online.com/web/p/ic-socket-adapters/7419669/

Bryce.

auberon
26th November 2015, 13:59
Hi! Thanks a million for your help/info, Demolition & Bryce! When I visited the shop you mentioned, I thought the numbers shown there were the part number, not the price.... :-D But this is crazy! This plug's made out of gold-pressed latinum, or what? I think I'll try using an old 84-pin PLCC chip, as Demolition suggested...

Thanks again,

Auberon

Bryce
26th November 2015, 14:23
When I was looking for a PLCC32 one of these, I struck lucky by finding a Chinese product (Breakout board) that had one on it. The board cost a lot less than the single part. However PLCC84 might be more difficult to find.

Bryce.

Strangely, the double height version from the same company cost a 1/3 of the price??
http://uk.rs-online.com/web/p/plcc-sockets/4350652/

auberon
26th November 2015, 15:05
This is totally absurd! But I think even this higher version will fit nicely without modifications to the A2000's guts, so maybe I'll give this one a try. Anyway, what confuses me is the 1,27mm pitch mentioned in the datasheet. The pitch should be 2,54mm for Agnus to fit.....? Or is this simply the pitch of the "outside" pins to make soldering a bit easier? The datasheet is quite unclear.

Hm, hmm. This 2 MB chipram thing is going to be an adventure, I can feel it. :roll:

Auberon

Bryce
26th November 2015, 15:11
Nope, PLCC is always 1.27 J-Type pins. There was never a 2.54 PLCC.

https://en.wikipedia.org/wiki/Chip_carrier#Plastic_leaded_chip_carrier

Bryce.

auberon
26th November 2015, 15:16
Oops...I see, thanks for enlightening me! I believe I got confused with all these pitches during my research. :o