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Tapped lightly on the shaft, the collet released, and the impeller came right off. The collet is indeed broken. That's quite fragile (as stated) as I don't recall putting very much torque on that shaft at all.

Now that I have the impeller off, though, I still cannot lift the LVPS out because the motor shaft protrudes through the hole in the rear plate. Does that shaft normally stick out that far? If not, then maybe I displaced the shaft in this process.

If the shaft does normally stick out that far, then how does one extract the power supply? The manual states it should just lift out but it's a pretty tight fit and I can't see where I can tilt it far enough to let the shaft clear the frame.

Stumped again...

Thanks,
Barry - N4BUQ

----- Original Message -----

From: "Chuck Harris" <cfharris@...>
To: [email protected]
Sent: Monday, August 5, 2019 11:00:42 AM
Subject: Re: [TekScopes] 2445 LVPS Issues

It is a plastic collet, in a plastic taper. The two practically
weld together after being under tension for many, many years.

The screw is molded into the plastic collet, and turning the screw
relative to the impeller will break the screw free of the collet,
such that it will never be able to pull the collet tight again.

Don't turn the screw!

Move the nut to the end of the screw, and tap it with a light
hammer. That hit will push the collet out of the taper, and it will
release. Don't pull up on the impeller when you tap the screw, just
let it hammer against the motor's endplay washer. You aren't hitting
it hard enough to do any damage....Right???

Once you have the collet off of the shaft, you should send a drop of
light machine oil running down the shaft, and into the bearing.

And, on the other end, use your desoldering station, and slurp the
solder from the center hole of the circuit board (inline with the
shaft), and oil that end too. Just a single drop on each side.

-Chuck Harris

n4buq wrote:

Searching for Tektronix "impeller" vs. "fan", I finally found a picture of
the collet:



That makes sense to me now. Still unsure how turning the screw damages the
collet (presuming the fingers stick to the tapered ID of the impeller and
a twisting motion breaks them) but I'm guessing I'll find out soon enough.

Thanks,
Barry - N4BUQ

----- Original Message -----

From: "Barry" <n4buq@...>
To: [email protected]
Sent: Monday, August 5, 2019 9:12:01 AM
Subject: Re: [TekScopes] 2445 LVPS Issues

Okay, Chuck. I presumed it was a collet but wasn't sure how to release
it.
Unfortunately, I did turn the screw some in a CCW direction and then back
again so it sounds like I may have damaged the collet. Ugh! Too tempting
and the manual doesn't give any caveats regarding that (only states not to
remove the nut which I can't really see what that would hurt either but,
perhaps, because it might bind on the slotted burrs and cause the screw to
turn). If I can get the impeller off, I'll see what kind of damage I may
have caused. The impellers are still available but I'm guessing the
collet
isn't.

Thanks again,
Barry - N4BUQ

----- Original Message -----

From: "Chuck Harris" <cfharris@...>
To: [email protected]
Sent: Monday, August 5, 2019 8:25:19 AM
Subject: Re: [TekScopes] 2445 LVPS Issues

It is easy:

Put a screwdriver in the slot of the screw, and use a wrench to
turn the nut against the screw (DON't LET THE SCREW TURN!!!)

Back off the nut until it is flush with the slot, and give the
nut a light tap with a hammer. It will move into the squirrel
cage a little bit, and then the squirrel cage can be pulled off.

If you let the screw turn relative to the squirrel cage, it will
destroy the delicate plastic collet... you don't want to do that!

-Chuck Harris

n4buq wrote:

Got everything removed except the fan. Any hints/tricks to getting that
off? Loosened the nut but the fan blade won't budge and I don't want to
pull any harder unless it is recommended. I have a feeling that's some
kind of collet and perhaps pressure on the slotted screw would release
it
but just don't know.

Thanks,
Barry - N4BUQ

----- Original Message -----

From: "Barry" <n4buq@...>
To: [email protected]
Sent: Saturday, August 3, 2019 9:30:54 PM
Subject: Re: [TekScopes] 2445 LVPS Issues

And there, on page 6-25, is the complete process spelled out very
neatly.
Just didn't expect that.

Thanks,
Barry - N4BUQ

----- Original Message -----

From: "n4buq" <n4buq@...>
To: [email protected]
Sent: Saturday, August 3, 2019 9:03:44 PM
Subject: Re: [TekScopes] 2445 LVPS Issues

I didn't realize the SM would go into detail on board removal. I will
read
up on it there.

Thanks for the tip on the incorrect silkscreen too.

Thanks,
Barry - N4BUQ

----- Original Message -----

From: "Tom Gardner" <tggzzz@...>
To: [email protected]
Sent: Saturday, August 3, 2019 7:10:03 PM
Subject: Re: [TekScopes] 2445 LVPS Issues

The service manual is quite specific on how to remove the various
boards.
It
isn't difficult, if follow instructions.

The manual is available at the usual places, e.g. tekwiki.

Be aware that on some of the 24x5* series the manual and silk screen
show
two
caps swapped. So when recapping, remove and replace a single
capacitor
before
moving on to the next; don't remove them all and then start replacing
them.


On 04/08/19 00:13, n4buq wrote:

I was using my 2445 today when I heard a strange sort of thump noise
coming
from inside the scope after which I started smelling a burning odor.
I
had a few pieces of gear powered up at the time but quickly could
tell
the
smell was coming from the 2445.

I took off the case and top cover and pretty sure the smell is
coming
from
the LVPS board(s) but am a bit stumped at how to get those two
boards
out.
I'm pretty sure the top ribbon cable needs to come off but don't
quite
see how to get the large plastic cover off of the area where the
main
filter caps are.

Looking at some of the smaller caps, they appear to be leaning due
to
(I'm
guessing) bulging at the circuit board end but not sure exactly what
overheated (or, possibly, made that thumping noise).

Are there instructions somewhere that outline how to remove those
boards?
If not, could someone provide a couple of hints to get me started?

Thanks,
Barry - N4BUQ