A7000 floppy / HD issues

Arc/RPCs, peripherals, RISCOS operating system & ARM kit eg GP2x, BeagleBoard
sirbod
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A7000 floppy / HD issues

Postby sirbod » Thu Feb 02, 2017 10:25 am

I have a sickly A7000+ which randomly doesn't detect the floppy drive and refuses to detect HD's. Originally I had a IDE->SD adapter on it, so to rule that out I've put an IDE from another Arc on it which has the same result. !HForm reports its failed to detect the drive type and power doesn't appear to be an issue as the drives do spin up.

Has anyone come across this issue previously, or have any tips on how I might diagnose the problem. I don't suspect line breaks or dry joints, it visually looks okay, but I will short-test the lines at some point just to rule it out.

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danielj
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Re: A7000 floppy / HD issues

Postby danielj » Thu Feb 02, 2017 10:49 am

The SMC controller in those is really sensitive to static iirc, and does both IDE/FDD? FDC37C665 was the code I think.

d.

sirbod
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Re: A7000 floppy / HD issues

Postby sirbod » Thu Feb 02, 2017 11:17 am

I'm leaning towards battery damage around the FDC37C665 chip, which is right next to where the battery would be. I can't see any damage visually and I did change the battery when I purchased it before it was corroded, but who knows what happened before I got it. For all I know, the battery may already have been changed from a previous leak.

Short tests on the underside of the board came up clean, so I'm working my way round the top side. There are also some surface mount caps around it which need checking.

Pity there's no diagrams for the board.

sirbod
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Re: A7000 floppy / HD issues

Postby sirbod » Thu Feb 02, 2017 7:43 pm

Now that I've removed the board and scrubbed it, its clear there was battery damage at one point. I've checked all the resisters and capacitors in the area, so the issue is likely to be a broken track. I've checked all of them, except for the three I've highlighted below that go under the C13 text.

Does anyone know where they end up at? Tracing them, they appear to go under the floppy socket and into the IDE although I'm not 100% certain. Without another board to compare against and no circuit diagram, I've hit a dead end :?

A7000.jpg

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danielj
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Re: A7000 floppy / HD issues

Postby danielj » Thu Feb 02, 2017 7:47 pm

That track just left of the Via north of C13 looks a bit dodgy - can you use sharp probes through the solder resist on either end to check if there's a break?

d.

sirbod
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Re: A7000 floppy / HD issues

Postby sirbod » Thu Feb 02, 2017 8:21 pm

The track are too narrow to avoid damaging them, so I'd risk making the problem worse. That left track looks worse than it is, the pixies freely run its length.

sirbod
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Re: A7000 floppy / HD issues

Postby sirbod » Tue Feb 14, 2017 1:55 pm

sirbod wrote:I've checked all of them, except for the three I've highlighted below that go under the C13 text.

Does anyone know where they end up at? Tracing them, they appear to go under the floppy socket and into the IDE although I'm not 100% certain. Without another board to compare against and no circuit diagram, I've hit a dead end :?

I took a guess at where two of the lines were going and soldered wires in, this has fixed the IDE 8)

For future reference, the left line goes to the via under the R6 text. The middle line goes to pin 4 on IC2 (not pictured, but it's south of the IDE connector). The right line goes to pin 5 on IC2. Pin 4/5 are the 4th/5th in from the left of the south side of IC2.

The right two were partially corroded from battery damage and were showing resistance.

sirbod
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Re: A7000 floppy / HD issues

Postby sirbod » Mon Feb 20, 2017 2:29 pm

Seems it's not as fixed as I first thought. Managed to reinstall !Boot and had it all working after several reboots.

After a power cycle however it goes back to reporting "Disc not understood - has it been formatted?"

Sounds like a software issue to me as the CD-ROM seems to be okay. I've even tried removing the CD-ROM to no avail.

Anyone seen this issue and know the fix?


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