17 Sep
2012
17 Sep
'12
12:58 p.m.
I have powered up the LA36 with the Selenar Graphics board in it, and
from the information kindly obtained by list members (Byte Magazine
article about the Selenar Graphics II), I have been able to verify that
the unit indeed works. The graphics mode works, and all of the other
features documented in the Byte article seem to function properly.
The issue that I've found is that only 5 of the 7 print pins are
working. Numbered with the top pin as number 1, it is the 3rd and 6th
pins that are either not firing at all, or are jammed such that they
can't come forward enough to make an impression.
I assume this is nthe standard LA36 pinthead.
The first thing to do is to remvoe it can clean the business end with
propan-2-ol. Take care not to use toomuch, you cna disolve the adhesive
that holds the synthetic gemstone bearing in place.
Now, fro mteh DEC printset, check the resistance from each of the drive
connections to the common conenction. They should all be much the same.
If pins 3 and 6 test open then either the coils are burnt out (==new
printheat time) or more likely the flexiprint conenctiong to the head is
broekn. Often this can be carefully repaired.
Then use a bench supply, one side to the common conention, otehr side ot
the pin 1 derve. Turn up the votls and wath the pin. See what sort of
votlage makes the pin extend, and how far out it comes. Repeat for the
other pins, Do pins 3 and 6 behave i nthe same way?
If hte head is OK, next step would be the driver s o nthe power supply
obard (IIRC). I doubt the problem is further back i nthe logic, fortunately.
-tony