And we're back in action.
And with an unusual problem.
It seems that CAS is high all of the time on U44 to U47 on my Mega, hence only seeing the 2mb of ram when using the SMT MMU. Plug the old MMU back in and its back to 4mb right away. Continuity to pins 17 and 18 from the ram chips is fine. I'm just wondering if it's anything to do with the type of ram that I'm using. I've got the SOJ20 to 20pin DIL adaptors with 514400 ram installed.
Edit 1
Just looking at the ST schematic in comparison to what I have and the resistors on the schematic for the CAS lines show 68ohm. I'm measuring 35ohm on all 4 connections. Now to try and track down a C103277 Rev 2.2 schematic
Edit 2
And 33ohm is what its supposed to have. on /WE /RAS /CAS etc. /OE is low on all ram chips and /WE is high, so at the mo I have no idea. when I plug the PLCC MMU back in it works straight away at 4mb. This is also the second SMT MMU i've used and its exactly the same.
@exxos, when you checked your MMU, was it on a 4mb ST?
MMU SMT ADAPTERS - WIP
Re: MMU SMT ADAPTERS - WIP
If it ain't broke, test it to Destruction.
Re: MMU SMT ADAPTERS - WIP
It was a 1MB machine. But I will try and get it tested on my 4MB one tomorrow.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
Re: MMU SMT ADAPTERS - WIP
Can you also try booting a floppy with it please? My Gotek wont boot with that MMU installed but once again, put the old one back in and it boots.
This Mega has had all the floppy patches btw.
If it ain't broke, test it to Destruction.
Re: MMU SMT ADAPTERS - WIP
I always use floppy.. So its working fine In fact I have been testing 1772 chips most of yesterday, so formatting 1.44 floppies loads all day. No issues.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
Re: MMU SMT ADAPTERS - WIP
It might be my Ram playing up AGAIN. I'll have a look at this over the next few days but I think my Ram was ok, until I did the usual playing around to double check all the connections for/OE etc, so would still be cool if you can rule out the 4mb thing. At least I'll know I have to find ANOTHER day joint in my Ram circuit then.
Old Ataris. Who in their right mind would have one!
Old Ataris. Who in their right mind would have one!
If it ain't broke, test it to Destruction.
Re: MMU SMT ADAPTERS - WIP
Just got home, tried my 4MB machine and it sees and tests 4MB fine. So the SMT MMU board is good.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
Re: MMU SMT ADAPTERS - WIP
Ok thanks. More repairs needed.
I think I may just dump the ram and fit a 4mb upgrade, bypass all the old stuff.
I think I may just dump the ram and fit a 4mb upgrade, bypass all the old stuff.
If it ain't broke, test it to Destruction.
Re: MMU SMT ADAPTERS - WIP
Will try it in my Alpha board later on but I'm quite sure it works.
Not bragging but I did some of my best SMT work when I soldered the replacement chip in.
Then time to fix the Mega, put a TF534 in it and leave it alone
Not bragging but I did some of my best SMT work when I soldered the replacement chip in.
Then time to fix the Mega, put a TF534 in it and leave it alone
If it ain't broke, test it to Destruction.
Re: MMU SMT ADAPTERS - WIP
Amusingly my Mega now works again, thanks to a dodgy pin on a socket and with the original MMU I see 4mb. Still only see 2mb with the new one.
I'll dig out the STF Remake and try it on there. Going to leave this poor old fragile Mega alone now (at least until I get my pak back or put a TF534in it )
I'll dig out the STF Remake and try it on there. Going to leave this poor old fragile Mega alone now (at least until I get my pak back or put a TF534in it )
If it ain't broke, test it to Destruction.
Re: MMU SMT ADAPTERS - WIP
Think that MEGA is very poorly!
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.