Re: TransWarp GS repair questions

[Michael J. Mahon <mjmahon@aol.com>]

Conrad <conrad.russo@gmail.com> wrote:
> Hi guys,
> 
> So I placed an order for everything besides the power supply yesterday. I
> will be ordering the supply shortly. Here is what I picked up:
> 
> Genius G540 Universal Programmer
> No Name EPROM Eraser
> W65C816S6PLG-14 CPU 
> 3 CY7C199CN-15PXC 15ns .3 wide SRAM
> Gold plated machine pin sockets
> 
> I decided to not order the 70ns SRAMs since from what Steven said and
> I've read they would most likely just be useless. I plan to mount the
> sockets in the same way most people mount the SRAMs to the board, with
> the legs bent to 90 degrees and lengthened to reach the .6 wide
> through-holes. As I mentioned before I have a professional grade vacuum
> pump desoldering station, so I will properly desolder the old SRAMs
> instead of cutting them out at the chip and using the leads to connect
> direct to the new chips like some people suggest doing. Since I can I
> feel its better to keep the old ones then to destroy them in the removal
> process. The power supply that I plan to buy has the following specs:
> 
> Voltage +5V -5V +12V -12V +3.3V +5V-SB 
> Current 15A 0.5A 16A  0.8A 15A     2.5A

Just one warning--you can short a supply line to ground on an Apple II and
just make the power supply chirp. With a PC supply like you're using, a
similar momentary short will likely vaporize some traces!

> Wayyyyy more than enough for the GS but I figure that is the best way,
> since once I install that, there will be no risk of too much draw on the
> supply ever again. Hopefully, all of these upgrades and tweaks will fix
> whatever is causing the issues. If not... time to break out the rework
> station and the logic probe and really get my hands dirty. The CPU,
> SRAMs, and sockets will arrive probably Monday and the programmer and
> eraser will come in a few weeks. I chose the Genius G540 over the TOP853
> because of various issues people have had with the latter. Anyway, I'll
> let everyone know how it well it goes. If the programmer works well I
> will offer programming of ROMs, uControllers, and PAL/GALs for the
> community. Results to follow soon!
> 
> Conrad


-- 
-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon