Atari Mega ST 2 Blitter issue

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qq1975b
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Atari Mega ST 2 Blitter issue

Postby qq1975b » Tue Jun 12, 2012 6:59 pm

Hello,

I bought an Atari Mega ST, and when I opened it to clean it well I noticed it hadn't the Blitter chip....I managed to get one but when it is inserted, thed FD doesn't work properly (doesn't read) and system fails just when you move the cursor on the desktop (the cursor disappears ). The workbench is in german and it seems that is an old Mega ST2 because I think it can't read the DD FD (but it has the WD1772).
I have attached some pictures, so you can see the blitter chip and the mainboard. I would like to replace TOS with a newer version (maybe is the problem because the german version doesn't has the blitter option, but I couldn't check it with it inserted because the cursor disappears...), but I don't know how to burn the Hx and Lx parts to an EPROM (27C256) yet (but I have the files made).

What can I do? Is it possible to make it work with the Blitter?


One other question is...what is the 6pin power connector without any plug in it (close to the PSU)? There are two of them, one next to the other. The other one is plugged with a 6pin power connector.

Thank you for your help :)
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Re: Atari Mega ST 2 Blitter issue

Postby ST-Freakz » Tue Jun 12, 2012 8:08 pm

there are 2 solder blobs / jumpers you need to remove from the motherboard

i can see them on your 2nd picture

just in front of and to the right hand side of the blitter, when you remove them you will see 2 solder pads

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Re: Atari Mega ST 2 Blitter issue

Postby qq1975b » Tue Jun 12, 2012 8:22 pm

Do you mean the black thing in a red circle? if I remove the plastic will it work?

thank you
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Re: Atari Mega ST 2 Blitter issue

Postby ST-Freakz » Tue Jun 12, 2012 9:19 pm

what! that's not a jumper 8O

do not touch that part at all!

see attached pic

also you need to check you have the blitter in the correct way also
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Re: Atari Mega ST 2 Blitter issue

Postby qq1975b » Wed Jun 13, 2012 9:48 pm

Done and working!
TOS replaced too with v1.04

All OK but I think I have to replace floppy disk drive because can't read or format HD to DD adapted (shows an error on one side formatted disks too)

By the way, can you tell me where the red wire from the battery goes? Numer 1 or 2? It desoldered and I don't know where each one goes...

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Re: Atari Mega ST 2 Blitter issue

Postby ST-Freakz » Wed Jun 13, 2012 10:07 pm

HD to DD adapted? :?

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Re: Atari Mega ST 2 Blitter issue

Postby qq1975b » Wed Jun 13, 2012 10:15 pm

I mean using a high density disk with the left hole covered/blocked....
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Re: Atari Mega ST 2 Blitter issue

Postby ST-Freakz » Wed Jun 13, 2012 10:36 pm

qq1975b wrote:I mean using a high density disk with the left hole covered/blocked....


i thought that was what you mean't

forget it! that's what's giving all the "drive problems"

you need to use 720K DS DD disks only

if you need any let me know..

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Re: Atari Mega ST 2 Blitter issue

Postby qq1975b » Thu Jun 14, 2012 5:15 am

Ok. I will do it as you say.

Do you know about the red and black wire I asked (connection of the batteries connector to the mainboard)?

Red in 1 and Black in 2, maybe?
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Re: Atari Mega ST 2 Blitter issue

Postby DarkLord » Thu Jun 14, 2012 5:25 am

qq1975b wrote:Ok. I will do it as you say.

Do you know about the red and black wire I asked (connection of the batteries connector to the mainboard)?

Red in 1 and Black in 2, maybe?


Follow this picture, should help:

Mega ST - clock_battery_wires.jpeg
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Re: Atari Mega ST 2 Blitter issue

Postby qq1975b » Thu Jun 14, 2012 8:50 am

Perfect!!! all done then :D

Thank you.
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Re: Atari Mega ST 2 Blitter issue

Postby qq1975b » Thu Aug 23, 2012 6:20 am

Hi,

One question...in an Atari Mega ST...can I use Ultrasatan with this DMA chip number (first photo)?

C025913-38


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Re: Atari Mega ST 2 Blitter issue

Postby Chandler » Thu Aug 23, 2012 7:45 am

qq1975b wrote:Hi,

One question...in an Atari Mega ST...can I use Ultrasatan with this DMA chip number (first photo)?

C025913-38


Thank you.


yes

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Re: Atari Mega ST 2 Blitter issue

Postby qq1975b » Fri Aug 24, 2012 10:04 am

Ok, thank you...so this DMA chip only fails in an Atari STe, doesn't it?

Thank you!
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Re: Atari Mega ST 2 Blitter issue

Postby Nikolas » Wed Aug 29, 2012 6:44 pm

yes

Ultrasatan works fine on st machines i have stf and stfm
If you guys expirience hardware problems.
1. Always remove chips if possible before soldering.
2. Resolder your hardware, check cables too.
3. If problem continue THEN must be faulty software.

I got 2 Atari ST
Main is stfm, with blitter, with 4 meg of ram, with 16mhz cpu + s-video and audio input to videobox, vdi out
P.S.
My english may not be correct

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qq1975b
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Re: Atari Mega ST 2 Blitter issue

Postby qq1975b » Wed Aug 29, 2012 6:50 pm

I said that because is the same DMA chip that is known as the famous faulty chip on the STEs. So, the chip isn't faulty. The problem is that it can't attend the STE requirements.
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Re: Atari Mega ST 2 Blitter issue

Postby Nikolas » Wed Aug 29, 2012 6:54 pm

Probably is problem in code tos in ste, ste is different machine..
If you guys expirience hardware problems.
1. Always remove chips if possible before soldering.
2. Resolder your hardware, check cables too.
3. If problem continue THEN must be faulty software.

I got 2 Atari ST
Main is stfm, with blitter, with 4 meg of ram, with 16mhz cpu + s-video and audio input to videobox, vdi out
P.S.
My english may not be correct


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