1040STE don't like floppy drive

[doc]

Hi everybody.

I a some floppy trouble with my 1040 STE.
First let me say that my floppy drive and the floppy i plug inside are both working well and tested on another ST. So the problem does not come from them. No it's rather a problem on the mother board or some ships.

Here are the facts :
Test 1 - Boot with the floppy drive + floppy : the floppy spins then it stops then i get a white screen and I can't do anything more.
Test 2 - Boot with the floppy drive (with no floppy in) : Acces to the green desktop ok. I then push the floppy in, opens it and I get the bee icon... I can't do anything more.
Test 3 - Boot with no floppy drive (so no floppy either ) : Acces to the green desktop ok

Well I'm really scratching my head . What the hell can it be ? I did all the test with exxos diagnostic cartridge and :
1 - RAM is OK
2 - ROM is OK
3 - Blitter is OK
4 - keyborad is OK
5 - DMA Port test says : D0 DMA time-out Fail at Cycle:000001 (may be it's normal)

Oh, I forgot to say... my DMA is a -38 one and I suppose (but i hope no) this could have something to deal with the trouble.

Any inquiring idea ?
Best.

[exxos]

I would suggest you start with the mandatory fixes for the STE before trying to diagnose anything as the problem may already be solved anyway.

[doc]

Ok thanks. I read all this very carefully.
So I just ordered everything that could help me. I'll make the fixes one after another and test the results.
I assume I first must recap the PSU and the Big cap, then change the CPU.
If all that fails, i'll test the capacitor buses change.

[rubber_jonnie]

I'd also have a good look at the cable, both ends and check continuity.

[doc]

Good idea... I gave a look and all seems to be fine this way but I assume I'll have to desolder the socket and check again to be fully precise...

Another question about this motherboard. Can anybody identify this mod shown on the pictures ?

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On the solder side, Pin 1 (or 2 not sure) on the shiffter is wired to buses resistor pin 9 on P105

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In your opinions, would this mod be related to my floppy troubles,

[rubber_jonnie]

I wouldn't advise de-soldering the floppy connector on the mainboard unless you have proper de-soldering equipment. If you do have the correct gear, then fit a floppy socket to the mainboard instead and make a floppy cable, its a worthwhile upgrade.

As for the bodge wires, unless you can specifically tie them to the floppy problem,then you would need to leave them as is. The white hot glue is a good indicator that they are factory mods, and as such you will probably cause more problems by removing them.

As for what they specifically do, I don't know.

[doc]

So I stated the mandatory fixes.

1 - First PSU recap.
Here are the voltage before recaping (the PSU is disconnected from the STE and uses load capacitors for the test)
5 v -> 4.3v
12v -> 10.7v

After recaping :
5v -> 3.5
12v ->9.8 v
Isn't that strange ?

I assume it is a problem with the load capacitors (2.2 and 10 oms)
So i plug the PSU on the mother board, switch the STE on and read again :
5v -> 5.2v
12v -> 12.2v
Feels good I was sure a capacitor load trouble ...

TESTS : the ATARI still cannot boot when the floppy is attached

2 - Replacing the 4,700uF axial capacitors with exxos cap replacment kit
TESTS : Still no change

3 - Changing the CPU for MC68HC000 one
TESTS : Still no change

As rubber_jonnies suggests, I think I'll now give a look to the floppy cable and check continuity... but I first must find a new cable that fits.

[exxos]

There is the pull-up resistors on the LS06 (I think ) invert chip.. Also possible the chip itself is faulty.

[doc]

Hi Guys!

So I continued the mandatory fixes to try to fix my floppy trouble.
Quick reminder : If a floppy is connected to my 1040STE it frezzes to a blank screen...

1 - Removed the parity ships on the 4 simms (mandatory 2) -> Nothing changes

2 - Did the 1772 pull ups fix (mandatory 4) -> Nothing changes

3 - Changed the LS306 for a new one -> Nothing changes

IMG_5708.jpg (147.72 KiB) Viewed 4264 times

4 - Desoldered the floppy connector and soldered a new removable one. Made my own flat floppy cable and tested point to point -> Nothing changes

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IMG_5709.jpg (117.13 KiB) Viewed 4264 times

5 - Did mandatory 3 (floppy wrhte protected) by soldering a 10K bussed resistor array to the 1772 databus pins -> Nothing changes

IMG_5712.jpg (129.35 KiB) Viewed 4264 times

6 - Had a attentive look to the tracks of the motherboard looking for any cut -> Nothing spetial noticed


What I noticed too :
1 - It doesn't work either if a satan disk is connected... blank screen
2 - On a reset I get either nothing / 3 bombs / 11 bombs
3 - The floppy motor runs two times and its light is working too
4 - I don't know how this was possible but I once had de floppy icons on the desktop, but a clik on was writting "error reading" and no read. I was unable to make it appear again... I assume that the floppy cable was badly inserted...
5 - This may have nothing to do this the discussing trouble but the background (and the white freezing screen) is in fact "PINK"

IMG_5707.jpg (51.81 KiB) Viewed 4264 times

So here is the point where i am. I must admit that I'm near to give up... It will at the end cost me more in components than the machine itself.

Would ou have some more suggestions ?

[exxos]

That is odd... Ultra Satan should not effect the screen colours.. Maybe the 1772 or DMA itself is blown..