Earlier this week, I had trouble with my main 5200. So I got out my box of backups and the first one I tried wouldn't start so I opened it and found these seemingly factory modifications that I've never seen before. System can be fixed(needs ANTIC chip) and is not a * numbered version.
Just thought I'd share.
Looks like an iffy 400 pokey jammed on a 5200. Did it by chance come in a small "Corp" box? 1985-86 5200s were often leftover non-"*" 4-ports. Rumor has it that Atari "Corp" pulled every scrap out of "Inc's" storage, slapped it together and sold it.
That one came in a batch of 3 "dead" systems I'd bought for parts. The top on it is so badly warped, carts won't stay in the slot. The bottom on it is the later 2-port style with the extra hole for power socket though.