Need help identifying these Atari 520ST modifications

[chad5200]

Have a 520ST with motherboard C070243 REV. B.

 

Can someone help identify the various modifications on this board?  Are any of these OEM?  Looking to reverse anything here that was not original.  Thanks!

 

Top Side Picture 1:

 

 

Top Side Picture 2:

 

 

 

Top Side Picture 3:

 

 

 

Bottom Side Picture 1:

 

 

 

Bottom Side Picture 2:

 

 

 

Bottom Side Picture 3:

 

 

 

[bfollowell]

Is there any sort of output coming out of that non-OEM looking box? Anything coming out the back of the case?

 

All the ST motherboard revisions I see on Exxos' site, all have a blank, unpopulated section about the size of that box, right where it is in your picture, but none of them have anything installed there.

 

I'm wondering if it's a modulator circuit, which the STs didn't officially have until the STMs and STFMs started coming out.

[chad5200]

The box is RF out.  That is OEM.  I hooked it to my TV on Channel 3 and it works great.

 

I think this is a very early 520ST.  

 

Those other cables sticking out the top (that have since been cut) appear to be a composite out modification.  But I cannot test it out as the cables are cut.  However, two small holes were drilled in the case as pictured here.

 

 

[tjlazer]

Actually the very early 520ST’s had no RF and had TOS boot roms.

 

[anzac]

This one is clearly marked as 520STmodulator

 

it does appear to have had some kind of composite work done