A cheap way of replacing the battery is to install a Lithium Calculator Battery. This solution was described to me by Skybeaux (Ken) a while ago, after he commented on my previous method of installing expensive memory capacitors. This is also an easier method

 

Nice work Nino - that board looks sweet.  How much are the lithium batteries+holder?  Caps are only around $5 and solder straight onto a MPU-200 as though they were made for it!  On 100's and Bally's you need a short jumper wire.

cheers
Ian