Panasonic JU-475-5 AKO shows up with only maxtrack=41

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Achimito
Posts: 7
Joined: Sat Feb 09, 2019 10:47 pm

Panasonic JU-475-5 AKO shows up with only maxtrack=41

Post by Achimito » Thu Apr 25, 2019 5:15 am

Hi there,

I am really confused about a new non-modded Panasonic JU-475-5 AKO drive which I just bought from eBay:

dtc -c2 shows up with only maxtrack=41 :o

I thought this drive is a true 80+ track drive? Am I somehow mistaken or did I buy a fake Panasonic JU-475-5 AKO drive? I am very confused about it.

Thanks for your advise,
Joachim

SomeGuy
Posts: 212
Joined: Wed Feb 18, 2015 8:18 pm

Re: Panasonic JU-475-5 AKO shows up with only maxtrack=41

Post by SomeGuy » Thu Apr 25, 2019 5:38 am

One possible reason is the head is hitting something as it seeks an inner track. Check that there is nothing in the way and that the rails the head assembly moves on are clean.

Can you see the head moving as the kryoflux seeks? There might be a metal shield you have to remove to see the head assembler.

Go ahead and treat it as an 80 track drive and watch the head move. If the head reaches the innermost position after only 40 tracks, then it is either a 48tpi (360k) drive or it has a jumper set to emulate one. (I don't know if that model has such a jumper)

Achimito
Posts: 7
Joined: Sat Feb 09, 2019 10:47 pm

Re: Panasonic JU-475-5 AKO shows up with only maxtrack=41

Post by Achimito » Thu Apr 25, 2019 6:29 am

The head is moving freely, i.e. there is no obstacle on the rails the head moves on. But the head does only travel half its way from the outer to the inner track. I can clearly see when removing the metal shield covering the head assembly.

Maybe it is a jumper issue? The following jumpers are currently set as follows:

DD: open
AT: closed
GX: closed
EX: open
DC: closed
DA: closed
HS: closed

DS3: closed
DS4: open

That´s all I can spot of the jumper settings.

Can anyone please verify his/her jumper settings and compare to mine?

Is there a manual for the drive which descrives the jumper settings?

Achimito
Posts: 7
Joined: Sat Feb 09, 2019 10:47 pm

Re: Panasonic JU-475-5 AKO shows up with only maxtrack=41

Post by Achimito » Thu Apr 25, 2019 6:47 am

I have just found a jumper setting description via Google, so I can be more precise with the jumpers currently set on my drive:

TH: OFF
DD: OFF
AX: OFF
AT: ON
1E: ON
GX: ON
EX: OFF
MS: OFF
RDY: OFF
DC: ON
HA: OFF
DA: ON
HL: OFF
HS: OFF

BX: OFF

DS4: OFF
DS3: OFF
DS2: ON
DS1: OFF

1M: OFF
OP: ON

TM: ON
ST: OFF
OF: OFF

RY: ON

Looks not wrong to be according to http://www.bitsavers.org/pdf/panasonic/ ... umpers.pdf .

Is my drive useless/broken/dead ?

Thanks for any advice!

Achimito
Posts: 7
Joined: Sat Feb 09, 2019 10:47 pm

Re: Panasonic JU-475-5 AKO shows up with only maxtrack=41

Post by Achimito » Thu Apr 25, 2019 6:57 am

The only 2 jumpers that confuse me are:

HS: ON (factory-soldered in ON-state; should be OFF according to manual)
HL: ON (factory-soldered in ON-state; should be OFF according to manual)

HS is used for "Head loading controlled by Drive Select (not used)"
HL is used for "Head loading controlled by Drive Select and Ready (not used)"

Any idea if these two factory-soldered connections could be the culprit(s)?

Thanks for any help.

SomeGuy
Posts: 212
Joined: Wed Feb 18, 2015 8:18 pm

Re: Panasonic JU-475-5 AKO shows up with only maxtrack=41

Post by SomeGuy » Thu Apr 25, 2019 3:21 pm

Head loading refers to a mechanical device that lifts the to head up when the drive is not in use in order to reduce disk wear. Those were mainly needed in drives that kept the disk spinning all the time. It sounds like your drive does not have that, although the board design supports optional circuitry for one. Either way, that would not interfere with the maxtrack test.

1E (selects 96 or 48TPI) was the one I was thinking about and that seems to be set right. If the head only moves half way, then this is not the problem anyway.

Do you have a formatted 96TPI (80 track) disk you can try to dump? (Start with one that is unimportant just in case something gets messed up.) Go ahead and try to dump it and see what the results are. In the GUI just manually fill in "81" (typical value) for max tracks in the options section. On the CLI just specify the tracks you want as usual.

Achimito
Posts: 7
Joined: Sat Feb 09, 2019 10:47 pm

Re: Panasonic JU-475-5 AKO shows up with only maxtrack=41

Post by Achimito » Thu Apr 25, 2019 3:26 pm

Meanwhile I did further dtc -c2 tests without the metal shield and I am sure that some mechanical problem does have to exist to prevent the head from moving any further than track 41. But to further investigate I would have to disassemble the drive rail mechanics. I will see whether the eBay seller will exchange the drive for me before I decide to disassemble it. I even fear doing any harm to my KryoFlux board the longer I leave the drive attached to it even it really seems to be a mechanical problem only.

Thank you very much for your help so far. I will further investigate the mechanical problem (I believe).

SomeGuy
Posts: 212
Joined: Wed Feb 18, 2015 8:18 pm

Re: Panasonic JU-475-5 AKO shows up with only maxtrack=41

Post by SomeGuy » Fri Apr 26, 2019 4:03 am

I'm not familiar with that specific model of drive, but with the metal shield off of the top you should be able to access the head assembly and enough of the rails to see and clean the parts that matter. It should not even need disassembly unless some unlikely specific problem is identified that needs it.

With the top shield off, no disk in the drive, and the drive powered down, you should be able gently push the head assembly back and forth along the rails. (When the power is on the head will try to stay firmly in place). You should just be able to use a q-tip to reach in and wipe off the rails and remove anything that is obstructing the head.

You really should test read a disk to be sure of the problem.

Achimito
Posts: 7
Joined: Sat Feb 09, 2019 10:47 pm

Re: Panasonic JU-475-5 AKO shows up with only maxtrack=41

Post by Achimito » Fri Apr 26, 2019 4:10 am

Hi there,

I just got the drive repaired (and flippy-modded at the same time). The culprit of maxtrack=41 was really the head drive rail which was really stuck at track 41. I disassembled the drive rail and tried to drive the head along the rail by hand. The cause for being stuck at track 41 seems to be old light machine oil which got resinified (if that´s the correct term to be used for that matter).

As I disassembled the mechanics anyway I just flippy-modded all mechanical parts as described in the 3 Youtube videos by SPS. Only the PCB still needs to be modded.

A dtc -c2 command now shows a Maxtrack of 83. :-)

Thank you so much, SomeGuy, for all your help. It is highly appreciated by me.

Kind regards,
Joachim

P.S.: I don´t want to become offtopics, but I am still confused why dtc -f<diskname> -i4 doesn´t seem to produce a error-free .img file of double-sided DD disks. But that´s maybe worth anouther thread.

SomeGuy
Posts: 212
Joined: Wed Feb 18, 2015 8:18 pm

Re: Panasonic JU-475-5 AKO shows up with only maxtrack=41

Post by SomeGuy » Fri Apr 26, 2019 3:28 pm

On double density 48tpi disks, don't forget to specify -k2 for double stepping, and -dd1 to specify low density mode.

You may eventually find it is more useful to dump as a kryoflux stream file and then decode with DTC or other tools later.

General advice when having problems decoding: post a stream dump for others to look at.

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