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Re: I have a 15MHz IIgs!



On 11/04/2012 04:20 PM, Steven Hirsch wrote:
On 11/04/2012 11:25 AM, STYNX wrote:

The removal of the org. socket is not that hard. I used a Dremel-drill with
a cutting disc to carefully remove the plastic bridges of the socket
(don't touch the board in the process!). After that i could just install
the additional (cut in half) socket (sometimes i had to desolder the holes
in the middle of the socket). I did not bother to completely remove the
unused socket. The remaining socket residue :-) will not hinder you in the
following upgrade anyway. If the socket has to be completely removed there
is the possibility to damage the Board. The result of a easy socket
upgrade will not look as nice as a completely new socket but will do the
same job. I mainly used a unsolder-iron and unsolder-wick.

I'll probably do that for the data ram.  For the tag ram, I used the tried and
true approach of crushing the plastic on the old socket with pliers and
pulling the pins one by one from the top.  It's a PITA, but a better bet than
trying to pull the socket intact with a vacuum desoldering rig.

The board is quite a bit better with the UMC tag ram. It doesn't lock up at
all now.  But after a few hours it will crash into the monitor when I try to
start a large application like Sprectrum, WPGS, etc.  I'll try the Alliance
chips next and plan on modifying the data ram for .3" packages next week.

Well, that didn't work so well. I modified the data ram sockets to take .3" packages and installed the UMC 20ns chips for all 4. Crashes immediately after the desktop appears 100% of the time. Tried (4) different brands of SRAM with no improvement. Swapped the oscillator for another 50Mhz. unit, no improvement.

This was a big step backwards. Before I remove the 1/2 socket that I added and put back the older .6" packaage SRAMs, do you have any other suggestions?

I'm using "74ACTQ" series parts for the two chips at the bottom (these were the ones Henry Courbis was selling as upgrades). Do you still think swapping those for 74S parts is of any advantage?

Steve