Gunstar Posted March 8, 2007 Share Posted March 8, 2007 (edited) I finished this upgrade to my 1200XL with the Rambo XL 256k upgrade already installed, but after testing it's not working. But before I go searching for the problem, I may know what it is already, but need some verification: The upgrade instructions detail desoldering one end of a 33 ohm resister at R108 on the motherboard, this is the proper location of this resister on the 800XL, but not on the 1200XL, the instructions suggest to trace from pin-15 on the memory chips back to the proper 33 0hm resister on the 1200XL. I did this and the location I thought was right was the 33 ohm resister at R100 on the 1200XL. Can somebody who has done this 512k upgrade please verify that I'm using the right resister/location or if I'm wrong and if so, where is the correct resister location? It's the spot where pin-1 of the 74LS139/74S139 chip is connected at the pad where the 33 ohm resister lead was removed and where pin-5 (74LS139) or pin-4 (74S139) are connected to the lifted lead of the 33 ohm resister(location R108 on the 800XL). Edited March 8, 2007 by Gunstar Quote Link to comment Share on other sites More sharing options...
Gunstar Posted March 9, 2007 Author Share Posted March 9, 2007 Well, never mind, I figured it out, and it was just a simple problem, as they usually are; I had the location of R100 on the 1200XL right, I just lifted the wrong end of the resister and had the wires going to the pad and resistor lead crossed. My 512K XL is up and running! Quote Link to comment Share on other sites More sharing options...
mimo Posted March 9, 2007 Share Posted March 9, 2007 If my 1200 ever turns up I will be wanting to do this one Quote Link to comment Share on other sites More sharing options...
Gunstar Posted March 9, 2007 Author Share Posted March 9, 2007 I'm done upgrading this one for a little while, though I'm seriously considering and internal SIO2CF or similair type mod. And if that new graphics board for the 8-bit is ever released I'll be upgrading to that. Maybe a 65816 upgrade someday? Quote Link to comment Share on other sites More sharing options...
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