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Thread: Aligning Floppy Drives

  1. #71
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  2. #72

    Default 50th Anerversary Mustang

    Sorry, I did not get back to anyone yesterday. I had to drive to Orland and help my daughter buy a new car.

    So, now I am the Best Dad Ever !!! LOL!!!

    Ford Mustang.jpg
    Last edited by Novell2NT; August 26th, 2019 at 10:32 AM.

  3. #73

    Default 2.4.12 Amplitude Test

    It looks like the document you are looking at does not match my drives. I believe that you are looking at the SA400L Service Manual. I noticed a couple of big differences.
    So, to be on the same track, this is the document that matches my SA400 drives.

    http://deramp.com/downloads/floppy_d...e%20Manual.pdf

    Did you have a chance to look at my Scope settings to see if I have things setup correctly? Do, I need to turn on the Math function, to add and invert TP-1 and TP-2? (Look at attached pic)
    Like I said, I am a novice with my scope, so to get the correct reading, I will need help to make sure everything is setup correctly.

    2.4.12 Head Amplitude Check 1.jpg

    This is what I get, when I use the Math function and ADD CH1 + CH2. Is this what I am expected to see? (This is the good drive)

    2.4.12 Head Amplitude Check Scope 1.jpg
    Last edited by Novell2NT; August 26th, 2019 at 10:31 AM.

  4. #74

    Default

    Quote Originally Posted by MauriceH View Post
    IMD. image disk program has a analysing tool in it.

    I use it also for 8".
    You can attach the drive to a PC dos or win computer.
    With several known good FFDs you can observe per track sector if data is allined.
    That through the nummeric field.

    Great tool.
    Can you tell me more or direct me to the IMD image disk, hat you are referring to?

  5. #75
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    Default

    Maurice was directing you to the ImageDisk utility, which has several useful functions. You supply the formatted floppy disk from a known-good source.

    At this point, it seems we have several cooks tinkering with the stew, so I'll bow out here.

  6. #76

    Default

    Only one channel should be inverted and then that add to the other.
    Dwight

  7. #77

    Default

    If you are using a scope in that manner with the two channels added and one inverted (to make what amounts to a pseudo differential probe) make sure that each scope vertical amplifier channel is set on exactly the same sensitivity, volts/cm. Set both channels for DC coupling initially, short the two probe tips together for a test, center the trace, then to be 100% sure it is all working apply both the probe tips across a test reference, like a 1.5v torch battery as a test, and observe the amount of deflection to familiarize yourself with the way this "differential probe" is working.

  8. #78

    Default

    Quote Originally Posted by Dwight Elvey View Post
    Only one channel should be inverted and then that add to the other.
    Dwight
    Thanks Dwight, but no one is telling me, if I am actually setting my scope up correctly. I have never synced my scope to an external signal, How do I make sure the External Trigger is being used?
    I think I can see that up in the right top corner of the screen. It is being hidden under the MATH settings that are currently up, in the first pic. But it is setup wrong as it is Yellow or CH1 in the pic.
    Although it did not seem to make a difference when looking at the signal. Of course, that could just mean, that I am doing something wrong.

    What should the Trigger Mode be set on? Edge or Alternate?
    I have also never added one channel to another. It appears that I need to use the MATH function for this to work?
    I am pretty sure that I only have CH2 inverted.

    When I have CH1 and CH2 and MATH lit up, I have 3 signals, but if I only have MATH lit up, it looks like I can add CH1 and CH2 and verify that CH2 is Inverted.
    So, I am guessing all I need is MATH turned on, is that correct.?

    Does this look like the correct output for the Head Amplitude Test?

    One other question that is bothering me a bit, is that Since I have two drives hooked up, it does not seem to matter which drive is actually selected, as I get signals on drive 2, even though I am only
    loading the head down, on drive one. Why is there any signal at all on Pin 1 and 2 of drive 2, when I have drive 1 selected??? How or am I getting a correct amplitude reading???

    2.4.12 Head Amplitude Check Scope Settings 1.jpg 2.4.12 Head Amplitude Check Scope 1.jpg

  9. #79

    Default

    Quote Originally Posted by Hugo Holden View Post
    If you are using a scope in that manner with the two channels added and one inverted (to make what amounts to a pseudo differential probe) make sure that each scope vertical amplifier channel is set on exactly the same sensitivity, volts/cm. Set both channels for DC coupling initially, short the two probe tips together for a test, center the trace, then to be 100% sure it is all working apply both the probe tips across a test reference, like a 1.5v torch battery as a test, and observe the amount of deflection to familiarize yourself with the way this "differential probe" is working.
    Ok, I set my math function up as shown, and I have both CH1 and CH2 connected to the 5V square wave on my scope.

    Is this what a differential reading is supposed to look like?

    Test.jpg

  10. #80

    Default

    This is where an analog scope would be better. The spikes are time sampling errors. With both leads connected to the square wave, you should have a flat line.
    If you have an input bandwidth limiting switch it might be worth trying to set it to a lower band width. The signal we are looking for is around 4 MHz.
    You are suppose to be triggering from the index pulse with a third probe.
    Dwight

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