"Mike S" wrote in message
news:14063834.146.1334859505608.JavaMail.geo-discussion-forums@ynnf1...
Hey guys,
I posted here recently about a problem where the back tension arm on my
VCR got pinned down by the left shuttle assembly during unthreading.

I've fixed that issue, and I've retimed all the gears. I'm pretty
confident that the timing is correct, because all of the holes line up,
and the unit can be easily threaded and unthreaded manually by turning the
worm wheel. Everything seems to move as it should, when it should.
(There's a possible exception with my right shuttle: It could possibly be
off by one tooth, since the gear looks slightly different from what the
service manual shows, and the arrows are unhelpful. However, moving this
gear a tooth in either direction does not affect my current issue, and
it's in the middle position of only three that allow the shuttle to easily
move all the way to both ends of the VCR.)

However, I cannot get system control to understand that the system is
properly unthreaded. Whenever I turn the power on, it tries to unthread.
If I start the gears out unthreaded, the motor will encounter resistance,
and the machine will error out. If I start the gears out threaded, it
will unthread, keep trying to go farther, encounter resistance, and error
out. If I disconnect the motor from the gears, it will time out, then
error out. It's always the same error, 09-821, which indicates the system
could not unthread in the specified time.

I've tried disconnecting the unit from power for hours at a time, and the
stupid thing still thinks it needs to unthread. The mode switch doesn't
use any levers or moving parts: It bounces light off of reflective tracks
on the back of the mode gear, which is perfectly timed with the rest of
the parts.

Does anyone have any ideas how to approach fixing this?



Have you tried it with the covers back in place ? Many VCRs do the oddest
things when bench light gets into the optical deck sensors. I don't think
that I have ever come across a deck that has an optical mode switch, but if
light got into that, I can imagine it would wreak havoc with the system
control. I'm trying to remember exactly what you said in your original post,
without going to look, but I think that it was all basically working except
for a fairly minor problem with the left loading arm nor withdrawing at the
correct time. If this was the case, and its now doing this new behaviour
after you realigned it, then the conclusion has to be that it is not aligned
correctly, no matter how much it looks like it is. I've been doing bench
work on equipment like this, for 40 years, as have many others on here, and
I think that we would all tell you from our own experience, that when a
fault 'changes' (usually for the worse like in your case) after you have
carried out some repair procedure, then the most likely cause is that you
have done something wrong yourself. I'm not specifically familiar with this
model, but if it's like most VCRs which use a conventional mechanical mode
switch, the timing of that switch relative to the rest of the mech is
absolutely critical, and completely unforgiving of being even a part tooth
out, let alone a whole tooth or more.

Arfa