RK07 questions

Tony Duell ard at p850ug1.demon.co.uk
Sun Jan 22 12:50:36 CST 2006

> Alright, I here are the results of my measurements on the RK07.
> My first step was to replace the 6-button/indicator panel with
> the *original* panel. When I got the drive, the "B" button was
> a little damaged, so that the white "B" plastic cap did not
> lock on properly on the button.   I had a complete panel, so
> I swapped the two. That was some months ago.
>  =
> As I connected the RK07 last week or so, I found out that two
> bulbs were defective, and replaced them after checking with
> the *Ohm meter* that those were OK.
> I wrote that the READY lamp did not light up, and I did check
> that the bulb was OK ...
> I had fixed the panel with the "difficult" "B" button cap, so
> I replaced the two panels.  The READY lamp goes ON!
>  =

Now what did I say about board-swapping ;-)....
> Great, the RK07 drive is OK, it must be something with the panel.

Well, we don't know it's OK yet. It could still have problems with, say, 
the data read/write circuits. But I think the servo side of things is 
doing the right things.

> I swapped the two panels again, and yes the READY lamp stays off.
> Again, I swapped the two panels, and took the suspicious panel to
> my shack (more test equipment available there).
> Applied +5V to the panel board ... RUN STOP, WRITE PROT and FAULT
> turn on, READY, "A", and "B" stay off.  For "A" and "B" that is
> correct as they are connected via an inverter.  Applying Gnd to
> the input pins of E1 (on the Operators Control Panel), and "A"
> and "B" turn on. But the READY lamps stays off; OK, so E3 is gone.
>  =
> However checking the input (6/7) and output pin (5) shows the
> correct functioning of this 75452!  Is the lamp defective again?
> This time (on the work bench) I did not use an Ohm meter, but
> the +5V power supply ... the lamps glowed *very* dim, barely
> visible! The lamp has a different rating!
> I installed a +6.3V type in the READY indicator; the panel works!
> Please don't laugh :-)

Having done that sort of thing many, many times, all I'll say at this 
point is that man-made faults are the worst to trace. Remind me to tell 
you sometime the story of the Epson QX10 graphics board that gave garbled 
displays after srolling, even though : 

All the components on the board were working correctly
There wwre no bad connections, broken tracks, dry joints
The links were set correctly
There were no missing components

Yes, it did happen to me, and the fault was most definitely man-made...

> BTW, an other good thing comes from this exercise: I checked on
> bitsavers, and there is no field printset of the RK06/RK06.

I believe there are rather more differences between the RK06 and RK07 
than, say, between the RL01 and RL02. The printset I have only covers the '07


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