RX02 Difficulties

[Aaron Jackson]

> On Dec 8, 2017, at 5:17 PM, Aaron Jackson <aaron at aaronsplace.co.uk> wrote:
>>
>>>> On Dec 8, 2017, at 12:53 PM, Aaron Jackson via cctalk <cctalk at classiccmp.org> wrote:
>>>>
>>>>> On Fri, Dec 8, 2017 at 3:03 PM, Aaron Jackson <aaron at aaronsplace.co.uk> wrote:
>>>>>>
>>>>>> Manual says it should be S1=off, S2=on for RX211 and RXV21
>>>>>
>>>>> In the photo, I think S1 is on and S2 is off. Check them with an
>>>>> ohmmeter if in doubt!
>>>>>
>>>>> -tony
>>>>
>>>> Yes - you are right. I switched them back to how they were when I got
>>>> the drive. I think one of the switches was half down because XXDP
>>>> actually does something now.
>>>>
>>>> Most of the tests now look something like this:
>>>>
>>>> CZRXFB0 DVC FTL ERR  00034 ON UNIT 00 TST 031 SUB 000 PC: 003476
>>>> SECTOR ADR - LGC TST
>>>> SECTOR ADDRESS ERROR
>>>>      EXPECTED SECTOR=18.
>>>>        TARGET SECTOR=17.
>>>>
>>>> I suppose these should match?
>>>>
>>>> Starting to think I might need to confuse myself with my logic analyzer
>>>> and the RX02 control board.
>>>>
>>>> Thanks,
>>>> Aaron.
>>>
>>> To isolate the problem further, try to see if any of the errors follow
>>> the media  as you move them between drives.
>>>
>>> If the same errors occur on both drives, regardless of media then the
>>> RX02 system board or perhaps the Qbus controller are at fault.
>>> The field maintenance prints should allow you to trace the fault down
>>> a bit further,  with or w/o a logic analyzer.
>>>
>>> How many different types of errors do you see?
>>>
>>> Jerry
>>
>> Thanks for the info Jerry.
>>
>> I get read errors, data errors, density errors, sector addressing
>> errors. Probably every kind of error xxdp can give :)
>>
>> Please see this link if you are interested:
>>
>> https://aaronsplace.co.uk/private/o/48859c14f6a619a5316d6af37d60579c.txt
>>
>> I will take a proper look through the field manuals tomorrow, and also
>> try what you suggested with trying the same media in both drives.
>>
>> Thanks,
>> Aaron.
>
>
>  When you have many errors it can be hard to separate the primary fault(s) from the knock-on errors.
>  The M7745/M7744 or Media Errors dominate the entries.
>
> 1) Try to verify the media is a DEC 8 Inch formatted RX02 or RX01 if you do not know the source of the
>      the disks.   The disk should have only 1 hole punched for index  on the media itself.   Even if it is
>      a DEC Brand, there’s still possibility that the media has been exposed to strong magnetic fields.
>
>      I have not seen much natural  bit-rot on my floppy media, but YMMV.   If could find someone local
>      with RX02 drives to confirm your media, that would also help rule out some things.
>
>       Many third party drives and controllers that were DEC compatible also had the ability to do a
>       low level format of media, something the native RX02 did not.  So if the media type is correct, but
>       the format is not, they may be salvageable (with complete loss of original data).
>
> 2) Check the connections between the drives and controllers. Gently clean contacts, especially anything
>     gold plated.  Getting clean signals from the floppies is critical if the RW electronics are to function.
>
> 3) Try and contrast to the other drive as previously covered.
>
> This will help rule out a few things and provide some better direction.
>
>
> Jerry

Thanks Jerry. That was very helpful. Found a stray piece of metal lying
across the board next to an AND gate, which is slightly
disconcerting. Possibly a stray wire clipping. Both drives pass the
diagnostics.

It's strange though, if I try to dump using vtserver using a floppy
which passed the diagnostics, it fails. So, not sure. Will have to
investigate a bit more.

Thanks again,
Aaron.