1040 STE PROBLEM.

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shaunboots
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Re: 1040 STE PROBLEM.

Postby shaunboots » Tue Jul 02, 2013 5:25 am

sorry no i dont think i have that one. still trying to figure this out so i will let you guys know how i go.

Guest

Re: 1040 STE PROBLEM.

Postby Guest » Tue Jul 02, 2013 9:29 pm

this one could be one of two ic's u305 {7406} 5parts used for floppy one part F to buffer the dma hdd iHDRQ signal


u201 {7406} is used to buffer the midi and control the reset of the machine

it goes wrong when the midi ports get zapped

also perhaps the header on the board where the floppy connects to the machines
or the drive end header is faulty

it sounds like this

a fault dma ic batch chip wont cause floppy read errors

the problem with the faulty dma ics is that the chip fails to switch from pio to dma mode on init command

if you simply switch the chip in driver to dma then pio then dma again and 'check mode'
then address the hdd this is a work around that icd {detected feked chip on boot} used to solve this without changing the chip

its a chip init post able and negotiation issue caused by the ic control register instructions miss alignment at hard ware level @$
but the driver can work around this if people cant find the ic
then a patch can be made to correct the post pio >< dma post init

if in hddriver you enable scsi reset at boot
i think this is part of whats up fixed and its not well documented but i see the issue

is pio to DMA switching at boot up
mostly is caused by the init of the IC mode and switched mode to DMA from inital PIO

when it switches the ic looses output till the ic is re accessed


there is room for a detection cycle here

again its down to uwe hddriver guy to add this preamble

Guest

Re: 1040 STE PROBLEM.

Postby Guest » Tue Jul 02, 2013 11:21 pm

please can you take some ~ 300-500k JPG images of your main board as is with the metal top removed

then we can all progress to help you more

as usual with all things physical

pictures speak louder than words

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shaunboots
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Re: 1040 STE PROBLEM.

Postby shaunboots » Sun Jul 07, 2013 11:47 am

hi simbo2 thanks for having a look at my problem. i really appreciate it. working on trying to get you some decent pictures. my camera is having some problems but ill see what i can do tonight. ive been pretty busy this week and got sidetracked with my stfm and trying to get my marpet xtra ram thingy working again. and i did! YAY! also i managed to use floimg program to extract files from a disk i thought was dead forever and make a new copy that works great! YAY again. but i still really want to make this ste work haha. ill see if i can find my old camera and get an ok shot from it... i cant find u201 anywhere.. i have u210 and its marked sn7046n . its the same ic as u305. is that the one?

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shaunboots
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Re: 1040 STE PROBLEM.

Postby shaunboots » Sun Jul 07, 2013 2:36 pm

here are a couple of pictures until i can get some better ones if needed... this is what happens when i load a disk.
DSC00029.JPG

here is my motherboard
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shaunboots
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Re: 1040 STE PROBLEM.

Postby shaunboots » Sun Jul 07, 2013 9:34 pm

oh and hey dlfrsilver i found scoop junior on this site. it should be up near the top of this page: http://thegamearchives.com/index.php?va ... 5_0_19_1_0

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Robson
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Re: 1040 STE PROBLEM.

Postby Robson » Wed Sep 26, 2018 8:33 am

I know it's a very old topic but this problem recently came across to me too. And posting one possible solution here. First I thought it's the exact STE that landed at my place because of the same mod (only my cross wire is green but missed that when first looked) and same kind of issue, wrong filenames read. My suspect immediately was the WD1772 and DMA (data between them). Socketed the DMA, WD1772, 7406, swapped them to known good ones as well. During the replacement I found some corroded joints that I had to repair as well. Checked the FDD cable just in case but this problem happened with external drive too.

The problem in my case was D4 data line short to GND at the DMA pins. I removed the mod but as suspected it has no effect on behaviour. So check the data lines between the 74245/wd1772 and DMA and their resistance towards GND and Vcc.

Wrong names (P = @)
42580266_10158063634522715_962592592980082688_o.jpg


Mod
42568170_10158063635542715_6385621435682914304_o.jpg


After repair
42576453_10158063634992715_4124419440370515968_o.jpg
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