Atari TT motherboard revisions: differences?

[qq1975b]

Hi,

I have two Atari TT each like each one of this link: http://www.mr2.net/marknias/atari_tt030.html

Both revisions are VERY different. Are they any known functional/technical differences between them? I mean relevant and compatibility/performance differences?

The one that is earlier revision gives me some problems with the same SCSI HDD that is fitted on the newer revision TT. It doesn't recognizes well the HDD when the other doesn't have any problem with it.

[qq1975b]

mmmm...on this earlier TT motherboard revision I have only made work a 50 PIN SCSI disc...no way to make work a 68 pin device.
An 80 pin HDD with adapter is not well detected: Loads HDDRIVER from itself but doesn't show any HDD attached Does anybody has similar issues with an early TT motherboard revision?

Thanks.

[qq1975b]

I am specially worried about the new CosmosEX with SCSI interface....

[qq1975b]

I have tried some SCSI HDD of 50 and 80 pin (with adapter) and I could only make work one old 50 pin SCSI HDD of 48MB
All the others didn't work properly...Sometimes the 9.1 GB 80 pin SCSI HDD that works perfect on my other Atari TT rev.K here it is detected...and sometimes is not detected... When detected it shows random partition numbers but in any case is useless because you can access to the partitions data.

[Guest]

you need to add the revc board scsi patch its something to do with the vme bus
i have a few pics of where to add the kinar wires and connects
some pins to cut and raise
no components
also change the clock a little to better time the scsi bus
ill look out the rev c board scsi patch details for you
rev a had just a 68030 running at 16mhz no pal chips {beside the mpu}
then rev b was the same but had a better clock setup
and you can by this time add the 32mhz mpu daughter board it has the pal ics added to it
rev c came with a gold top mpu mounted to the pcb and the pal chips also on the pcb
all three revisions suffered from the scsi issue with ahdi etc
you can read about it on DEVDOCS there youll find all the service release details
{well some of them}
as i say i made up a photo set for the upgrade of the machine you have
revc


rev d-k has the scsi patch built to the tracks

[qq1975b]

Thanks Sim

Mine is 32MHZ CPU.

[Guest]

yes
your machine is a REV C but hasnt had the scsi mod done to it

ill look now and find some pics for you
will take a day or two
you need also too be very precise

[Guest]

i dont see three red resistor packs at the rear of the scsi socket fitted

you need them if you use one drive only
and you also need them if you use only the internal or only the external sockets
if you use both you dont need them but it wont really complain if they are there

so fit them and try again

first and last device terminated
so this terminates the controller end
and enable termination on the drive

this is the problem

[frank.lukas]

68 pin SCSI Harddisks work well with the right Adapter, but not all Drives, I had some fujitsu drives that will not work at all. Some Seagate and IBM work well. 80pin SCSI drives are tricky. The unused 8bit from the 16bit SCSI bus must be terminated by a 50/68 or 50/80 pin SCSI Adapter or the whole 16bit SCSI bus must be terminated ...

[qq1975b]

On the later model motherboard SCSI was fine. All 80 pin hdd work well. The problem is the earlier rev one....no way to make them work ok.

[Guest]

res packs ctrlr term .jpg

you posted a pic of some other board

does your TT machine with issues
have the three resistor packs mouned behind your scsi socket

if you have these packs in place
and you have issues
esp as you cant see to access any wide drives .. its plug in and ok... and not plug and play
you need to add the same scsi chip as a falcon has the -2 type or a TT rev perhaps j-K same ic
this gives access better perhaps propper access to scsi 2 {wide}
i have i think 3 that are aok {maybe 2 are good }

check the resistor packs are correct and mounted correctly the right way round etc

i can help its the same number as most 'logics ics' but has a little failt -2 on it in falcons
some old scsi isa card have the wide chip if they have a wide port
my falcon has one and my rev j TT has one . -2c sometimes has a c on the TT not digin out the falcon

there is a post far back by mr atari about it he had a few of them also ... the -2 type or 2c whatever

but the falcon handles scsi 2 and 3 far better

so your TT can to .. by adding the plug in chip

i bet you feel good now you know you dont need to solder scrap in

L53C80JC2 {the dash two }

53C80 or some other pre nambular addin
the JC2 is the bit... in the falcon

[qq1975b]

Yes...I am relieved that I don't have to solder anything
I will check it this afternoon! Thanks!

[qq1975b]

It seems that the LOGIC chip is the same but there are not the resistors pack. Which ones are they, please? I will get them then

Later revision TT motherboard:

la foto 1.JPG

Earlier revision TT motherboard:

la foto 2.JPG

In this revision I don't see the back jumpers either...

[Guest]

hi
the res packs are 220/330 R 8 pin pin 8 + pin 1 -
they are arranged like this

8----/\/\/\/\....2
1..../\/\/\/\....2
8----/\/\/\/\....3
1..../\/\/\/\....3
8----/\/\/\/\....4
1..../\/\/\/\....4
8----/\/\/\/\....5
1..../\/\/\/\....5
8----/\/\/\/\....6
1..../\/\/\/\....6
8----/\/\/\/\....7
1..../\/\/\/\....7


https://www.google.co.uk/search?q=Thick ... 7gbn6IHIDw

here is a google search

youll find that jameco has them http://www.jameco.com/1/1/6729-4308r-10 ... 30ohm.html

or farnel etc
ebay i cant find any suitable ....

i did find this passthru terminator http://www.ebay.co.uk/itm/Active-50pin- ... 463509794e

but i think the main TT problem is you need to supply active termination voltage to the cable
this is i think why most of the drives you tried didnt work
as they require power to allow there termination to work correctly
and your other machine works ok because the controller is terminated

perhaps the drive you use has passive term... this applies to you frank also
this is prob why some drives you tried didnt work

so your ending up with no termination at all with your earlier machine
and no packs and no term power

check that the TMPWR pin 26 line on the scsi ribbon is being supplied with 5v active termination power
looking at the TT schematic pin 26 floats in all revisions... this is wrong

you need to modify the flat scsi cable or the machine
find its wire 26 and cut it then on the drive side you need to connect +5v via a diode and a fuse
or you can modify the socket adding the fuse and diode under the TT pcb to pin 26 scsi
to a +5v vcc source {like pin8 of any of the res packs}
use some sleaving to cover the mod and avoid shorting to the coating on the plastic base
as its conductive and also ground ....however usually there is a base card... to cover it {a must}

if you do this more types of drive will work {ones with no passive termination}
or ones that actually require this voltage
i recon any TT user should do this mod to there internal scsi socket

the falcon uses a diode and a 1amp fuse like this
vcc--->|---fuse---->> active term power
the diode is a 1n4001 1amp 50v piv

the fuse you can use a 1amp circuit protector {to92 package}
http://www.ebay.co.uk/itm/ICP-N25-Inter ... 3aa0c45cc3

youll get one far cheeper and faster from the local TV repair guy

as for the controller the one in the falcon has a 2 stamped on it in lite white.. ink
{not part of the chips numbers}
if you can fit the one from the falcon to the TT then perhaps again yet more drives become avalible
its a different ic revision to support scsi 2 more fully ?? or the chip is aok at certain data rates ..clocks

i made a little mod picture

[qq1975b]

I have pulled out the network resistors from the working TT and nows it has the same issue as the non working one. I will fit them on the other TT when I get home to have lunch. If it doesn't work I will try the mod.

These are the resistors...what differences are between the red and the black one? Can they been found in Aliexpress.com?

[Guest]

same resistor

im sure it will work
i would do the mod to both tt machines infact all TT machines

then the internal port will work better with later drives

[qq1975b]

with the resistors the HDD is working fine!

I only need to find some network resistors :p

[qq1975b]

Will these work ok, please?

http://www.ebay.com/itm/200-pcs-RKL8B-2 ... 1c33606abb

[Guest]

Will these work ok, please?

http://www.ebay.com/itm/200-pcs-RKL8B-2 ... 1c33606abb

hahahahahahahaha 200 pieces??? lol for 12 bucks
thats a bargain ..!! 197 spares

[qq1975b]

didn't found any seller selling less
I'll get them then

thanks Sim

[Guest]

wait ill find you 3
mouser has them
http://www.mouser.es/Search/Refine.aspx?N=663897
so youll get them locally
http://www.mouser.es/Passive-Components ... ahZ1yzs1c5
will cost you like 10 euros tops !! they are around 70 euro cents each
perhaps you can take a bus and go get them or order on the phone or the net...
Contact Mouser (Barcelona) +34 93 6455263

[qq1975b]

I have sent them an email to know if I can pick the items up instead of shipping them. They are near Barcelona and near where I work

[qq1975b]

I didn't see this topic that explains the same problem...sorry

Here it is to avoid other people make the same mistake: http://www.atari-forum.com/viewtopic.ph ... 06#p268906

[qq1975b]

Going back to the topic subject....the two TT motherboards look very very different. All chips organisation is different. Was the rev A-C so bad that they had to change everything? Or was due only to the cost of each motherboard? (A-C was very expensive?)

No noticable or practical changes/differences between both motherboard designs?

[Guest]

one thing i noticed with frank lukas rev d board he sent me to fix the scsi
was that one of the diodes on the battery supply to nvram had been shorted out
removed
this is to boost the voltage avalible by .6v to the nvram
so you can use a 2X1.5v cells 3v not 3.6 as the old cell was etc.
so doing this mod you can add modern 3v lithium {two 1.5vs}