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Media test issue - clh333 - 09-24-2015

I have hardware v.1.1 firmware v.1.2, latest software update.  Testing various drives (TEAC DSHD, Panasonic DSHD and DSDD, Epson DSDD) using various media (3M DSDD, 3MDSHD, Maxell DSDD, and Noname??) the SCP performs all tests but without exception has failed the media test with every combination of drive and media.  Is it possible I am missing something?  It's hard to believe ALL disks are bad.


RE: Media test issue - admin - 09-24-2015

Run the media test. When it fails, click the IGNORE option and let it finish. Then, make an image of the disk you ran the media test on (index mode is fine). Send me the image (data@cbmstuff.com) and I can look at it. You can load the image into the editor/analyzer, read a track and click on the Display Flux button. You should see a thin straight line at the 8us point, with no stray dots anywhere. If you don't see that, then you definitely have a problem with the media and/or the drive.

I see about 2 good 3.5" disks out of every brand new 10 pack. Typically with 3.5" disks, it's the last 4-5 tracks that fail. I have yet to see a 5.25" disk fail. In fact, I had to destroy a 5.25" disk to make sure the media test was actually working on 5.25" disks.


RE: Media test issue - clh333 - 09-25-2015

Following your instructions I completed a test of 2 DSDD 5.25" disks, one from a generic manufacturer and one a "NOS" 3M disk.  Both tests generated an error on the first pass (at track 20 for generic, track 30 for 3M), which I ignored, but each passed without errors on a subsequent test.  I have uploaded test results with screen shots to data@cbmstuff.com.  The flux display for both disk images is, to my untrained eye, quite presentable.  I cannot account for the anomalous test results, but suspect they may be due to 30-year-old components.

However, in the process of testing I did discover that (at least some of) my previous attempts to test media were flawed for the following reason:  I have been using IBM360K, indexed, preservation as my settings on the SCP, and these settings are retained between sessions.  I have track 0 head 0 as my starting point and track 39 head 1 as the end.  This setting also persists from session to session.  However, each time I select Disk Drive Utilities that screen's track slider defaults to track 79 head 1 as the end point.  The settings from the disk copy screen don't carry over and the settings on the Utilities screen don't persist from session to session.  After selecting the correct parameters I sailed past tracks 0 and 1 where the errors were previously occurring.

The track 79 default does not seem to affect the "maximum track" test; the head extends as far as it can and no farther.  However, I can understand that the media test would assume different track parameters if the disk being tested is HD rather than DD.  

In any case, the more I learn about the SCP the more impressed I am with its abilities.  Thank you again for your assistance.
clh333


RE: Media test issue - admin - 09-25-2015

The start/end track for the media test is independent of the copier.

Changing the end track is not going to make any difference on track 0 or 1. So, it's just by chance those passed after you changed the end track. Are you cleaning your drive heads frequently? That's not an option when imaging/copying disks! I find that I have to clean the heads after every disk I image.

Your MediaTest3M image was fine, no issues at all. The MediaTestGeneric had a lot of errors, and either this disks is hard to turn in the jacket compared to most disks, or you might have a power supply issue for the drive. The disk could also just be bad, but there is a very rythmic pattern to the flux line that indicates a rotational speed issue.


RE: Media test issue - clh333 - 09-26-2015

I have been cleaning the heads with a Q-tip dampened with alcohol.  What do you recommend?  I've heard that the "disks" made for that purpose are ineffective and short-lived.

The power supply I've been using was furnished with a Kryoflux board.  It is labeled "PHOBYA Model RK-34-12/5 - 2000mA" and states that it outputs 12V at 2A and 5V at 2A.  Measuring 1x1.5x4 inches, it certainly does not have a very large capacitor inside.  I've never tested the output but that may be a source of ripple.  I'll try another source to power the drives and repeat the tests.

The generic disk is tighter in its jacket than the 3M.


RE: Media test issue - admin - 09-26-2015

I always use those clean disks, soaked with alcohol. I rarely use a q-tip.

The power supply is probably fine. It could be your drive belt is dirty, but more likely the disk is tight in the sleeve - like you have found.


RE: Media test issue - SomeGuy - 09-26-2015

(09-26-2015, 06:07 AM)clh333 Wrote: I have been cleaning the heads with a Q-tip dampened with alcohol. What do you recommend? I've heard that the "disks" made for that purpose are ineffective and short-lived.
Q-tips are fine if your drives and heads are easily accessible and you only need to clean ocasionally. But for more frequent cleaning, or for drives with less accessible internals, then cleaning disks are quite handy.

If you just want to know if some simple read error is due to a dirty head, then a quick pass with a cleaning disk is fine. If a Wabash disk decides to shed all of its oxide in your drive, then it is time to get the q-tips and alcohol - and perhaps a jack hammer Tongue . Visual inspections and thorough cleanings are a good idea for any newly acquired drive, or a drive that has not been used in a long time.

Most of these cleaning disks were labeled for only a dozen uses or so, but as long as you don't use them to clean up after a big mess they will last much longer.

(09-26-2015, 06:07 AM)clh333 Wrote: I cannot account for the anomalous test results, but suspect they may be due to 30-year-old components.
It's something on the disks, not sure what exactly. I've run in to that sort of thing with disks that were known to be quality disks and well stored. They look perfect, but throw errors the first few times trying to use them. After that, they work fine.


RE: Media test issue - admin - 09-26-2015

The cleaning disks only make contact with a small portion of the head, so as long as you move the head to a different (new) track, you will find that they last a long time.


RE: Media test issue - clh333 - 10-22-2015

Thanks for your suggestions.  I obtained the cleaning disks, 3.5 and 5.25.  The TEAC FD55GF is sitting in the top slot of the case, with the cover off, so I can get to the head easily.  Keeping the head clean is paramount, as you noted.

I still want to find a way to check the calibration of the drives, particularly the 5.25s.  I read in Troubleshooting & Repairing PC Drives & Memory Systems by Steven J. Bigelow (TAB Books, 1994) about a company named Accurite which makes diagnostic disks.  From what I can tell they used to manufacture the Dysan diagnostic products as well.

I found their web site at http://www.accurite.com.  However, I'm not having much success contacting them through any of their published channels.  Do you have any experience with the company or recommendation of their products?

-CH-


RE: Media test issue - admin - 10-23-2015

You will want the Accurite AAD 206-34 (P/N: 810251A). This disk has all of the various test tracks needed for aligning any 360K or 1.2MB 5.25" floppy drive.

You could also use the Dysan 224 alignment disk (same thing as Accurite's).