Amiga4000 fast ram problem

[Rambo60]

This is not my Amiga 4000 a friend send it to me to replace the caps but there was more problem as the battery has damage the tracks to the fast ram so we repair all the bad track but still the fast ram and the IDE will not work and the mouse and joystick port did not work all so we replace all four 74F245 one 74HCT174 and two 74HCT166D now the mouse work ok but the the fast ram still not work as one of the old 74F245 where Damage by the battery as I am not sure what to check as most of the parts are SMD.

 

[hese]

Can you post a picture of the battery area of the motherboard? Have you checked the continuity of the three vias under U850 (next to the battery)?

 

[bebek]

Check continuity from U850 (measured from pins) to pins on SIMM socket as per circuit diagram. Most likely vias are gone or connection between pads and tracks. Often U850 has internal damage to. It is worth to replace it if it is corroded.

 

[Rambo60]

I check continuity from U850 pin from circuit diagram to U853 all ok I found no problem and all the 74F245 all been Replace for the fast Ram
The four 74F245 pin 2,3,4,5,6,7,8,9, they have no pulse which go to the fast Ram
The four 74F245 pin 1,11,12,13,14,15,16,17,18,19,they have pulse

 

[hese]

What about the three vias I asked about?