I'm trying to estimate the number of Commodore Amiga 4000T produced (not the AT models), by collecting the serials. There's a thread here where I enter the serials. You can post your serial here or post it directly in the thread at BBoAH.

My 4000T skin is an AT but it's heart, mind and soul is C= . My motherboard is a C= 4000T Rev 2 "Ser. No. 2  1-10-94" (handwritten sticker). It's the yellow silkscreen with a Buster 11 in a socket as well as some small chips (pals/gals?) that the Rev 4 has surface mounted. The motherboard works but I lose the Zorro boards after a reset when it warms up. The Buster socket is visibly bulging (never had the problem with a quality 3000 socket) and it probably needs a cap job but I haven't gotten around to it. I did replace the AT power supply so that wasn't it. I've tried to take pictures before with a cheap camera but they didn't come out very well (fuzzy and poor lighting).

Is it normal to have a CBM motherboard in the AT version?

Not that I know of although I have heard of miscellaneous parts being thrown together and replacements being whatever was available during and after the chaos of the C= bankruptcy. Usually it's more common to find newer replacement motherboards in older cases.

Your mobo is probably the same as mine:

http://www.bigbookofamigahardware.com/bboah/media/download_photos/cc5297f7-34a6-4d2d-a2b9-4e78d9dd4eef.jpg

No. That looks like the AT/Escom motherboard. That board is green and my board is yellow. My board has the C= copyright 1991 printed on it although it's missing one C= symbol that the later boards received. My board has a sticker with the hand written serial number where the printed serial number appears on later motherboards. It's a (marked) revision 2 board where the AT board revisions probably started where C= left off. Don't ask me how or why it's in an AT case but it is. My guess is that all the C= stuff was shipped to AT and they assembled pieces to make money. Maybe it was sent as a replacement motherboard for a defective one when the 4000T was out of production. I don't know but I do have a C= 4000T motherboard in my AT case. Look closely at the pictures of the 4000T here:

http://bboah.claunia.com/a4000tc.html

Note that this appears to be a C= motherboard in an AT case also. Mine is more similar to that but a little different as I have noted. I think you have an AT/Escom motherboard in a C= case? The bankruptcy must have caused a lot of chaos.

Edit: My motherboard looks like this (same color):

http://www.bigbookofamigahardware.com/bboah/media/download_photos/a4000tmb_rev4_4.jpg

That board says "Amiga Technologies Copyright 1993" in the corner where mine says "C=  Commodore Electronics Ltd. Copyright 1993". I suppose I could have an early revision AT motherboard but then my motherboard has a fix (wire running from a Zorro slot to a chip). The motherboards shouldn't have needed a fix if AT/Escom received the latest schematics. The handwritten date by the serial number on my motherboard is rather late for a C= though, so I don't know.

Check your ROMS - the rev4 version from AT - has a ROM that says Amiga 1995: http://www.bigbookofamigahardware.com/bboah/media/download_photos/a4000tmb_rev4_4.jpg

You can also Check Ramsey  on the AT version it also says Amiga 1995.

If you have Commodore ROMS 1994 - it's probably a CBM motherboard.

Yellow motherboards - I see no yellow motherboards? My (green) motherboard has all the C= marks and also original Commodore ROMS and sits in the Original CBM case. Mine is pretty much identical to the motherboard in the article you link to.

It's green with yellow traces but I call that yellow. It's like a lot of the C= proto boards. Most C= motherboards are all green with green traces like yours.

Check your ROMS - the rev4 version from AT - has a ROM that says Amiga 1995: http://www.bigbookofamigahardware.com/bboah/media/download_photos/a4000tmb_rev4_4.jpg

They have hand written labels "4.70 Byte 0" and "4.70 Byte 1" and look to be Eproms.

You can also Check Ramsey on the AT version it also says Amiga 1995.

No Amiga on mine. It has a "C= CSG" at the top and says "CBM 1989". It is a revision 7.

If you have Commodore ROMS 1994 - it's probably a CBM motherboard.

It's defiantly unusual and probably is an early C= version.

WTH is up with the battery on that MB?  LOL.

It's just the stock soldered on lithium coin cell flipped upward. The 4000T came that way so leaking NiCad batteries are not a problem.

There were only a few chips that Amiga Technologies produced. Most of the chips in the machines they built were Commodore parts that were still kicking around. They also never updated the silkscreening on the 4000T boards - they all say Commodore.

Preproduction 4000T boards made at Commodore in 1993 (and shown at various shows) were yellow (like the Nyx prototype). Maybe some of those eventually ended up in users' hands?

Nice info to have about the motherboards