7 Jun
2009
7 Jun
'09
10:34 a.m.
This is a
well-known problem on all sorts of devices. Someitmes the
grease will soften with common solvents (propan-2-ol, etc). There's a
green grease used in some camera lans mounts that goes rock hard with age
and nothing wil shift it short of scraping it out....
yes... I had to clean it out of the raceway of the solonoid as well as
off the plunger. It was really like glue. WD-40 seemed to do a nice
job cutting it actually. I also
see that the stepper motor that actually turns the platen (or equiv
of) is not making a full increment each time. Sometimes it advances but
other times it de-advances. So, something it messed up in the stepper
circuit or the grease in that stepper motor has turned to honey too.
Maybe you've lost the drive to one of hte stepper phases. That can make
them step in thwe wrong direction sometimes. Great stuff. Cool to see all those TTL parts and not
a one of them is
LS or HCT or anything close. 74XX was it in 1973.
Well, at that time there was also 74Lxx (lower power, slower), 74Hxx
(higher power, faster) and 74Sxx (fast!). I've come across all those
families in classic HP hardware of that period.
Note that I have really good luck with modern thermal FAX paper in these
units. Around here it is readily available at office supply stores on
I am not suprised. I use it in my HP thermal printers with no problems.
My 9866A (full-width thermal printhead, it's a sort of line printer...)
just works....
I repaired an HP2761G (moving head thermal printer). I went to a
stationers locally, and all they had was 210mm wide paper, the 2761
having a 216mm wide chassis. I found if I positioned the roll just right,
it would work, and the head wouldn't snag on the edge of the paper. So I
machined a couple of brass disks to put on the paper roll spindle to hold
it in the right place. Worked fine, and I was happy until I went to
another branch of the same stationers to find they also had 216mm thermal
papepr...
98 ft rolls. They have a 1/2" dia core which
needs a piece of dowel
to support it in the 725 (and probably in the 733 too) and it is a much
I am sure I can make up something to hold it...
-tony