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Re: MegaST - something recient.
Posted: 20 Nov 2021 20:45
by Bikerbob
Exxos I am using original Atari drives on this machine, but do you think
https://www.exxosforum.co.uk/forum/viewt ... =17&t=1395
is worth it? the pullups on the buffer?
James
Re: MegaST - something recient.
Posted: 20 Nov 2021 22:19
by exxos
Bikerbob wrote: 20 Nov 2021 20:45
is worth it? the pullups on the buffer?
If it's in the mandatory fixes then it's not optional.
If you have a spare DMA, try it ?
Re: MegaST - something recient.
Posted: 21 Nov 2021 09:47
by rubber_jonnie
Ok, so the DMA is the one next to the FDD controller, and since it's in a socket, you could try just swapping it out.
You may want to have a look here too:
https://www.exxosforum.co.uk/forum/viewt ... hilit=mega
Ignore the memory issues, for me it was the DMA that was bad.
Also, since the DMA is already in a socket (They are normally soldered in), I'd use the schematic to trace all the endpoints from the socket on the back of the board to their next endpoints and make sure that they have continuity.
Mega boards don't fare well with rework like socket installs, so you may have bad connections that can be fixed with a bodge wire. I had to do that on one of mine.
Re: MegaST - something recient.
Posted: 22 Nov 2021 16:58
by Bikerbob
exxos wrote: 20 Nov 2021 22:19
Bikerbob wrote: 20 Nov 2021 20:45
is worth it? the pullups on the buffer?
If it's in the mandatory fixes then it's not optional.
If you have a spare DMA, try it ?
OH, ok, but you specifically say in that thread its for the 920 drive.. I will do it.. I am assuming it cant hurt if I am using original drives.
James
Re: MegaST - something recient.
Posted: 24 Nov 2021 20:58
by Bikerbob
So... I guess I can only say that in the case of this board.. the manditory fixes.. WERE NEEDED!!
I have been testing the board for 3 days now.. it's good. Final pics.
20211124_135835.jpg
20211124_135922.jpg
Re: MegaST - something recient.
Posted: 24 Nov 2021 21:08
by exxos
Bikerbob wrote: 24 Nov 2021 20:58
So... I guess I can only say that in the case of this board.. the mandatory fixes.. WERE NEEDED!!
I have been testing the board for 3 days now.. its good. Final pics.
So this solved your strange floppy problems ?
Re: MegaST - something recient.
Posted: 24 Nov 2021 21:12
by Bikerbob
All I can say for sure, is once the pullups were done, and I changed the on board C4 7400uf cap, after the first 2 days.. where I was still got some crashing.. I have now run that board with games, and gembench and memtest etc..etc.. and I have not been able to crash it.
The resistors on the 7406 I did today.. they did not make a difference???? but everything is still working.. so all good.
knock on wood I am considering this board working!! :)
James