Thanx Dean;
--- In TekScopes@y..., dhuster@p... wrote:
Steve, the T935 is the delayed-sweep version of the T932.
The T912/T921/T922 was plagued with a problem with the female
connector on the main board that connects to the power supply. It
was always developing cracked/cold solder joints. The cure was to
pull the supply out, suck the solder from every terminal of the
female connector on the main board and then resolder each, using
high
quality 63/37 solder and a good iron.
The ole "ringed joint" syndrome. I'll have to look at that again to
be sure it isn't an ongoing prob here.
The 212's biggest problem was batteries. And their batteries were
larger in diameter than "AA" cells, although folks have success
with
using "AA" NiCds in them. This day and age, I'd switch the eight
cells over to NiMH so that you don't get the self-discharge and
memory of the NiCds. I have (well, HAD until the batteries ruined
the scope during extended storage) that I built entirely from
defective parts (I had to make my own output board since those
NEVER went bad.
Yup, my expensive TEK replacement ni-cads whizzed into the PS board a
scant 2 years after installation. Still worked off ext 12V supply
after clean-up, but I wouldn't bet the farm on long-term reliability
now.
The vertical/timebase/trigger board on the side that I
used had no fewer than 8 open runs, some on the inner layer that
connected to rotary switch contacts through blind vias.
Thanx! This explains the intermittents neither myself or Bob Garcia
could nail down, primarily shielding probs.
I've pretty much now decided to retire it to the "cute li'l thingies"
shelf anyway. I'll just keep the others going and use the 310A for
the portable utility 'scope and the T932 for the bench, the 561,4,&5
for special projects.
Best; Steve
