RL02 Question

[Aaron Jackson]

I have turned up the amplitude just a little higher than I think it
should be. Instead of going into fault mode after loading a pack, the
READY light flashes about quickly. With the scope hooked up I can see
that it hasn't managed to find the first track yet. Not really sure what
it thinks it is doing...



Aaron Jackson via cctalk writes:

> Hi Andrea,
>
> Thanks for your suggestions.
>
> Checking the amplified output from the r/w heads is one of the first
> things I did. The voltages are within normal range, but only after I
> push the head a bit further into the pack.
>
> Although, I did not set the jumper to try the other head (I suppose I
> was always looking at head 0), so I've just tried this now. There does
> indeed appear to be servo burst data coming from both heads once I've
> manually loaded them fully. So I am not sure if this is the problem. I'm
> really hoping that the pack is not bad since I paid for a tested pack.
>
> I also checked the sector transducer output last night. The individual
> waves (i.e. from trough to peak) seem to be twice as fast, but the
> timings between two peaks is correct.
>
> The survo busts are correctly aligned with the sector pulses.
>
> So, from what I can see, the drive should spin up correctly, but for
> some reason it goes into fault mode. I am right in thinking that upon
> load, the heads should continue moving forward until the first track is
> found, right? I should not have to perform a seek manually from the PDP?
> If this is not the case, perhaps there is something else wrong.
>
> Thanks again for your input,
> Aaron.
>
>
>
> shadoooo via cctalk writes:
>
>> Hello,
>> I'm not an absolute expert, but I successfully fixed a couple of RL02 in
>> the past.
>> Adjustment to the head is only useful for azimuth, I think. The radial
>> position will be adjusted continuously using the servo tracks, so there's
>> no absolute position adjustment at all.
>> If the drive fails during spinup, I would check at least the following:
>> - the presence of spindle sector signal after digital conversion of pulses
>> from analog signal coming from the pickup.
>> - having disabled the servo linear motor (there's some jumper to setup,
>> check the maintenance manual), perform the motor spinup, then load slowly
>> the heads on the disk by hand, until you find the servo tracks.
>> - with an oscilloscope check the presence of analog signal of the servo
>> tracks on both heads, and it's digital counterpart after amplification and
>> threshold detection (expected level values in the manual). If you see
>> something strange, e.g missing or too short pulses, try to adjust the gain
>> with the trimmer on the head board
>> - enable again the servo, then load again
>>
>> My 2 cents.
>> Andrea


-- 
Aaron Jackson
PhD Student, Computer Vision Laboratory, Uni of Nottingham
http://aaronsplace.co.uk