[rescue] How to open a TK50Z-GA?

[Malte Dehling]

Hi,

In my limited experience, by far the most common cause for
malfunctioning TK50 drives is simply dust/dirt, not the electronics.  I
currently have 3 TK50s and all of them didn't work when I got them and
started working after some disassembly and cleaning.  The technical
manual explains the disassembly steps very well!

Cheers,

Malte


On Sun, Nov 07, 2021 at 03:02:55PM -0500, Mouse wrote:
> > This may help
> 
> > https://lastin.dti.supsi.ch/VET/tapes/DEC-TK50Z/EK-0TK50-TM-002_Jul86.pdf
> 
> Thank you!  I managed to find a work machine to fetch it from (I have
> no HTTPS support on my own machines, and lastin.dti.suspi.ch is not
> willing to serve it over HTTP).
> 
> > Under section 3.4.2 lights
> > Flashing:
> > Pushing the load/unload 4 times may clear the fault.
> 
> I connected it to the TZK50, since I note there is a good deal of
> drive<->controller interaction going on, even a sense pin that lets the
> drive tell whether it's connected.  Powered them both from the same
> supply (not the H78948BA).  This should operate same as in the case but
> with no SCSI cables connected.  Turned it on.  The red light on the
> TZK50 came on, as did the load/unload light on the TK50.  I did
> nothing.  After a second or so the light on the TZK50 went out.  A few
> seconds later the load/unload light on the drive started fast-flashing.
> 
> I then pushed the load/unload switch eight times (eight because it's
> not clear to me whether the "4 times" refers to four presses or four
> full cycles).  It went solid red at the first press and stayed that way
> until I was done.  I then left it (button out).  After a few seconds,
> it went back to fast-flashing.
> 
> > That being said lots more info in there that may help
> 
> There is indeed.
> 
> I find myself wondering whether the problem is with the drive or the
> controller.  Chapter 2 describes enough of the communication between
> the TZK50 and the TK50 that I am tempted to snoop on the DR CMD and DR
> STATUS pairs - or possibly the internal versions of those; I see a
> 26LS31 and a 26LS32 right next to the drive connector on the TZK50, so
> I'll be looking for pinouts for those.  Makes me suspect I might even
> be able to cobble together something to talk to the drive directly.
> 
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-- 
Malte Dehling
<mdehling at gmail.com>