[rescue] How to open a TK50Z-GA?

[Mouse]

>> I've got a DEC TK50Z-GA which appears to be broken.  I offered it
>> FTGH here on 2021-09-21 and heard nothing in response.  So I infer
>> nobody's interested - which is hardly surprising.
> I would be interested if it wasn't so heavy and far away and
> therefore expensive to ship...

I know the feeling.  I've passed on enough stuff myself (usually in
Europe, with me in North America)....

>> So I wanted to open it up [...]
>> But I can't figure out how to open it.  [...]
> The front bezel is attached to the cover and together they slide
> forward.  (You do have to remove the screws on the bottom of course.)

Thank you!  That did the trick.  I now have it apart.  (Friction was
high enough it wasn't obvious they slid until I used a bit more force.)

So, I now have

- A TK50 proper (and according to its markings it is indeed a TK50).
- A TZK50 SCSI<->TK50 adapter board, 5017638-01-B1-P2.
- A "LOADS BOARD", "5017162 01 A1", nominally 1.6 ohms of 5V load and
   12.5 ohms of 12V load.  (See below for details.)
- An H78948BA power supply, which I have been unable to find specs for
   but which presumably has a minimum load, or why the load board?
- Assorted wiring and sheet metal and the like.

The TK50 still appears broken.  Connecting it to power (from a
different power supply), I still can't get it to release the door lock.
The button's light is sometimes on solid, sometimes flashing fairly
fast (10Hz?); pushing it sometimes changes this, sometimes doesn't.
Unscientific feel says that leaving it untouched for long enough (which
can be just a second or two or can be more like 15-30 seconds,
depending on factors I haven't worked out), it goes into its flashing
state.  Sometimes, toggling it will take it to the solid state,
sometimes not.  If I knew the TK50 well (I don't) I might be able to
deduce something from this....

The load board, in case anyone cares, has 15 resistors of 24 ohms in
parallel on the 5V line, 12 resistors of 150 ohms for 12V, total draw
nominally 27.145W (though the resistors are only 5% and thus giving
five places of precision is silly).  Also, 10uF 35V caps, two in
parallel on the 12V line and three on the 5V line, and five small
orange devices marked, if I'm reading the tiny writing correctly, RSE,
224, ZNI, and 911.  (The R I'm particularly unsure of.)  Three of these
are in parallel between 5V and ground, two between 12V and ground.
There are also ten zero-ohm "resistors", which I can't see any point to
because the points they connect on the etch side are not separated by
anything and hence could have been connected with etch runs instead -
and for that matter there are two of them in parallel wherever they
appear.  (Though "etch side" is a bit of a misnomer, as it's a
double-sided board and thus both sides are etch.  I should perhaps have
called it the non-component side.  The component side is almost solid
conductor, apparently ground plane.)

I'm not sure whether there's anything of value here.  The TK50 proper
appears broken.  The power supply is less capable than widely (and
cheaply) available peecee supplies, in that it has a minimum load.  The
adapter board is of no use without a TK50.  And the load board is of no
use except with a power supply having a minimum load spec.  The only
use I see for any of them is as a source of parts, and not much of that
because there's only one socketed part visible, that being a 27C256 on
the adapter board.  (The adapter is a Z80 with stock support chips and
a lot of 74xxx logic.  The one piece that doesn't look stock is a PAL.)

That leaves the case, and, while it's a nice (and seriously rugged)
case, I doubt I have anything to put in it.  I could scarf up the SCSI
wiring and ID switch, but that's about it.

It's rather a pity, because, as I would expect from DEC of that period,
it is impressively well-crafted.

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