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ST225 Error 1780 on a 5170

platatomi said:
Removed those jumper wires, seems to make no difference.
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So you are still getting a 1780 error on start up.
From that we know that the 5170 is communicating with the controller, but what is failing is a 'recalibrate' operation.
You've checked the cabling, and at this point, lack of a terminator is the only known cabling issue.

Maybe that wiring did some damage to the drive (and hopefully not the controller).

It could be that in this case, a terminator is required. I can post you a terminator if you like, but presuming that you are in the States, it may take a while to get there.

On these old drives, a 'recalibrate' operation (and seek opertations) don't involve reading the surface of the platters. In fact, people with operational 5170 systems will discover that if they remove the data cable, running the 'seek test' part of certain diagnostic tools (e.g. SpeedStor) works. If they boot their 5170, the 1780 test passes, but they see the later 1790 test fail.

You could have a faulty control cable. Over many years, I've encountered a few faulty control and data cables.

This is where having spare drives/cables helps a lot - quickly isolating a problem cause down to a particular area.

If you let us know whereabouts in the world you are, it may turn out that a knowledgable forum member with working MFM drive lives very close by.
Testing the ST-225 is someone elses system is questionable due to the lack of terminator.
 
If I were to get a terminator, how would it attach? I see no socket or connector to plug it into. Does it solder directly onto the board?
 
platatomi said:
If I were to get a terminator, how would it attach? I see no socket or connector to plug it into. Does it solder directly onto the board?
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That's a worrying statement. The photo I posted as post #15 shows the terminator and the socket that it plugs into. I pointed it out.

Now I'm starting to think that the wires you removed had nothing to do with the terminator.
 
Sorry, it wasn't apparent where which parts were the terminator and which the socket. For lack of a good verbal description, here is a pic before removing jumper wires, and after.


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I am also getting a different error now, 1790 instead of 1780, and the drive seems to be much more active during POST.


And it is letting me perform a low level format in System Checkout!
 

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platatomi said:
Sorry, it wasn't apparent where which parts were the terminator and which the socket. For lack of a good verbal description, here is a pic before removing jumper wires, and after.
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Hmm. I've certainly seen various revisions of the ST-225 board, but never one which didn't have the terminator socket at the usual location for a ST-225. Maybe the socket is somewhere else. Or maybe the terminator is soldered to the board and there's a dedicated jumper to disable/enable it.

That yellow wiring looks like a homemade job.

platatomi said:
I am also getting a different error now, 1790 instead of 1780, and the drive seems to be much more active during POST.
And it is letting me perform a low level format in System Checkout!
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Okay. So more progress.
 
So it allowed an unconditional format but still returns a 1790 on POST and a 1702 when trying to read/write/verify. At post, it makes a seeking noise, then some clicking/grinding for a while, then another seek. The 1790 error comes after 4 or 5 of these cycles. This noise sounds like a mechanical problem, is it possible to open up the case to check things out without ruining the media/heads?
 
platatomi said:
So it allowed an unconditional format
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Note that some low-level format routines do no data verification. How do I know? In experimentation, I removed the data cable before the format.
What the situation is with the 'IBM Advanced Diagnostics for AT' floppy, I don't know.
So unless one knows that a particular routine does verification, one shouldn't assume that the low-level format was successful because no errors were reported.

platatomi said:
but still returns a 1790 on POST and a 1702 when trying to read/write/verify. At post, it makes a seeking noise, then some clicking/grinding for a while, then another seek. The 1790 error comes after 4 or 5 of these cycles.
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It really does sound like your drive is faulty.

One of my ST-225s has been doing the occasional 'click/knock of death' (on system start up) for a few years, but it still keeps going.

platatomi said:
This noise sounds like a mechanical problem, is it possible to open up the case to check things out without ruining the media/heads?
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There is always the risk of a dust particle causing a problem down track.
 
To cover all the bases, I am currently doing a standard initialization with speed store, going fine so far (half way done)

I am beginning to think the IBM Setup program stuff is faulty, because earlier its seek test failed immediatly with a 1702, and the speedstore seek test passed no problem. Does passing the seek test mean the drive is mechanically sound? If the heads can move freely and accurately (i think this is what the seek test checks), I see no other mechanical components that could be bad.
 
platatomi said:
I am beginning to think the IBM Setup program stuff is faulty, because earlier its seek test failed immediatly with a 1702, and the speedstore seek test passed no problem.
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Exactly what IBM disk are you using?

platatomi said:
Does passing the seek test mean the drive is mechanically sound?
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No.

1. On these old drives, the surface of the platter is typically not read by the controller in a seek operation (I've yet to encounter a MFM controller that does [not that I tried them all]). And unlike on more sophisticated drives, the ST-225 has no dedicated servo platter for its own use. Try doing the seek test with the data cable pulled out. If it passes, you know the platter surface isn't being read by the controller.
So, for example, if an ST-225 drive has an intermittent stepper motor, the drive and the low-level format program and SpeedStor aren't going to know. Such faulty drives will probably make a noise when the heads are attempted to be stepped below cylinder 0 (because the controller thinks the heads are further out than they really are).

2. The spindle and spindle motor are mechanical.
 
Mystery solved. Took the pcb off the bottom of the drive to see how things looked, and apparently somebody did some very strange things to this drive.



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I will remove this stuff and see if that helps.
 
platatomi said:
Mystery solved. Took the pcb off the bottom of the drive to see how things looked, and apparently somebody did some very strange things to this drive.

I will remove this stuff and see if that helps.
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It's quite possible that you're undoing factory modifications and actually making things worse; at least take notes of what went where.

At least we now finally know that the terminator's in place.
 
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compare with a working drive jumpers from another xt/at class system ... see if this is just normal factory jumpering. The st225 was used in many systems and very likely had many configurations. It was also a replacement drive that may have had to have been adjusted to act like some other drive. One of the joys of vintage computering, the archeology of an item's history.

without the docs or a comparison drive I'd leave it for now.

my 2 cents.

bd
 
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