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The 7633 I just got running had a stiff fan that needed poking to get started. It was replaced with a fan from my other now parts scope. The the scope and fan are so clean it almost looks like the unit was hardly used. My theory is the fan just stiffened up from years of sitting. Is there anyway to repair this thing? I would like to have a backup. I wanted to wait and ask before I started tearing into it. /g/TekScopes/photo/37195/3?p=Name,,,20,1,0,0

Hello Lop,
Apparently we will walk hand in hand with our two recently acquired 76xx scopes (mine is a 7623A).
When I opened up mine, the very slow fan was the first thing I realized. Before I opened it, I was just so happy that I thought the 7623A didn't even have a fan (oh man, that 464 fan sound is annoying!).
Well, not only it has a fan, but it was, like your very sticky.
Upon initial application of WD40, it didn't come loose immediately, as it's common when we use WD40, so powerful WD40 is at loosening these things.
But it seems that the oil / grease residue of this particular fan gets really, really sticky... almost like tar.
I`m sorry that I didn't take pictures of the process, but here's what I did:
1. Firstly, remove the fan from the motor's shaft. It comes off easily, but don't risk pulling it out by the blades. Insert a flat screwdriver between the motor frame and the fan and use it as lever, so to push the fan out.
2. On the two sides of the motor, there are two small aluminum baskets that are help in place by two bent tabs. they hold inside them two generous tabs of felt, that are there to store the lubricant that keeps the sintered (porous) brass wet.
Unbend the tabs so to make the aluminum baskets loose. They wont come out because they're on the inner side, between the fan's frame and the rotor, but making them loose will allow you to apply WD40 generously inside them. This will soften the old oil, as well as wet the lint tabs.
3. Then, apply WD40 the closest as possible to the joint between the shaft and the bearing, so to create some pressure for the WD40 to enter the gap.
I used my fingers to hold around the WD40 needle, the shaft, and the bearing plate, so to allow only space for the WD40 to go in but little space for it to come out, in an attempt to increase the pressure into the gap. I don't know if it really helps, but it gives you an idea of how desperate I was, because even WD40 was having troubles to loose this thing.
4. At last, to help accelerate the process, I attached the shaft to my drill machine, and applied some continuous rotation while I kept pouring in WD40.

After a couple of minutes, the shaft was turning completely loose.

As a last measure, knowing that WD40 oil is quite volatile and don't last too long (to remain as a more permanent lubricant), I applied fine machine oil (sewing machine oil) to the felt tabs, sparingly, so to soak them completely.
I let the excess drip on paper towel, then I put the aluminum baskets back in place, holding them firmly from the back and re-bending the tabs.
It's important to hold them tight in place WHILE you are bending the tabs, so that they hold firmly into place, otherwise they will rattle and make noise.

Wish you luck.

Rgrds,

Fabio

On 03/16/2018 09:01 AM, Fabio Trevisan wrote:

Well, not only it has a fan, but it was, like your very sticky.
Upon initial application of WD40, it didn't come loose immediately

This matches the way old Husqvarna sewing machines get.
Cleaning with solvent such as kerosene, then applying Triflow lube is best for
a good repair that lasts. Just adding Triflow can be enough in some cases.

You guys are awesome! Now that I know they are fixable That is my next goal. I just cleaned an old Dual turntable motor and it has the felt pads too. I added electric motor oil to them, the Zoom spout stuff. I love this forum. The people make it great. I hope someday I can give back some of the help I have got.

I`m sure there will be plenty of opportunities Lop,
Next question about this kind of fan is yours!
Rgrds,
Fabio

Hello the thread, question about these fans:

Do these motors use plain sleeve bearings,
do they use oil felts to supply oil? Or are
they using oilite bearings??

Thanks, Stan KO6YB

Hello Brasscat,
What a world of experts and specialists this is.
In my small world, I never thought there were different kinds of bronze bushings... To me, there was sintered bronze bearings, for cheapo, less demanding applications, and ball bearings for serious stuff.
I've got to do some research to answer your question, since I didn't have a guess of what "Oilite" meant.
Now I know there's plain sintered bronze bushings, often (but not always) made of phosphor bronze, and there's Oilite, which I understood as being a specialized type of sintered bronze bushing... one that's auto-lubricant (e.g. that doesn't require additional oil, IF I got it right).
Never having seen an Oilite bearing or, at least, not knowing that I saw one, I can only offer an assumption.
This fan has 2 very generous lint pads (say 1" x 3/4" x 1/8th") that surrounds the bronze bushing... So I THINK it's not Oilite.
Rgrds,
Fabio

Hello Fabio, oilite is a sintered bronze bushing which is impregnated with oil
while under vacuum. The sintered bronze is full of cavities. They are not un-
common. Reoiling oilite will not last that long, after the internal oil supply has
exhausted or hardened. Plain bearings need a means to supply oil. If it has
felt pads, then I would suspect it to be plain bearings. The felts need to be oiled.
Wikipedia has a nice article on oilite.

Stan

On Fri, 16 Mar 2018 12:41:47 -0700, you wrote:

Hello Brasscat,
What a world of experts and specialists this is.
In my small world, I never thought there were different kinds of bronze bushings... To me, there was sintered bronze bearings, for cheapo, less demanding applications, and ball bearings for serious stuff.

There's also sleeve bearings, which may or may not be lubricated (and
likely ought to be).

I've got to do some research to answer your question, since I didn't have a guess of what "Oilite" meant.
Now I know there's plain sintered bronze bushings, often (but not always) made of phosphor bronze, and there's Oilite, which I understood as being a specialized type of sintered bronze bushing... one that's auto-lubricant (e.g. that doesn't require additional oil, IF I got it right).

I think you do. Oilite is a sintered bronze, made up of tiny little
welded together bronze spheres. As such, it has a lot of internal
space. It's oil impregnated to "avoid" the need for continuing
lubrication. It is supposed to be permanent lubrication.

Cleaning them with a solvent may require them to be re-lubricated.

Sleeve bearings are a shaft running in a tube, I think there's no
question about lubrication, they have to be.

Never having seen an Oilite bearing or, at least, not knowing that I saw one, I can only offer an assumption.
This fan has 2 very generous lint pads (say 1" x 3/4" x 1/8th") that surrounds the bronze bushing... So I THINK it's not Oilite.

I think you're right.

Harvey

Rgrds,
Fabio

Oilite is a registered tradename for a sintered bronze
bearing material.

Oilite bearings need to be precharged with oil. This
is done by heating the bearing, and then placing it in
a container of oil. When the bearing cools, the fresh
oil will be drawn into the bearing. It doesn't have
to be real hot, probably about 100C... don't want to
ruin the oil.

When an oilite bearing is put into service, it is
common to put the oilite into contact with an oil
soaked felt pad. The worn out oil will be replenished
with fresh oil from the pad.

Oilite is more abrasive than the steel shaft (usually),
and when wear happens, the steel usually does the
wearing.

The oilite can get damaged through being run dry.
The little bronze lined cells... sort of like a sponge...
get smeared, or hammered, shut by the friction, and
rattling that happens when the oil runs out. They
can sometimes be cleaned well enough by heating them
to get the old oil (and dirt) out, and allowing fresh
oil to charge the bearing.

Usually, a bearing that has been run dry will not wick
oil adequately, and will just throw the oil you add,
and again go dry.

Also, it is imperative that oilite be run with close
tolerances. It works by meniscus action of the oil
in the oilite against the shaft, forming a film of
oil that supports the shaft... The shaft isn't supposed
to rub against the oilite.

-Chuck Harris

Fabio Trevisan wrote:

Very good explanation Fabio. It’s as if I was there. Thanks
Raymond C?té
KD9CCZ

Heaven goes by favor.
If it went by merit, you would stay out and your dog would go in.

-Mark Twain

Note that almost anything WD-40 can do, LPS2 can do better.

Zoro has a good deal on it but I have a word of caution :

Open and discard the box outside. I can't directly make an accusation (if that's what it even would be) but coinciding with receiving the package from them we got bedbugs. I can't be sure enough to make a stink about it so, I didn't. Just that now I am careful of everything, I unpack things out in the garage now.

I don't want to impugn their reputation at all, it is just better to be safe than sorry. It was a really good deal, and I bought enough to get a discount, I think it was free shipping or something.

I have used WD-40 and LPS2 on many things for many years and I prefer the LPS2. I have literally sprayed pots from the front without disassembly and it cleaned it because it has some components with extremely low viscosity. (yes, it is not conductive and stays that way)

If you use it to penetrate and want to not make a mess, (like a turntable motor recently) spray only a little into a container as it sprays too hard. Put it in a syringe or on a Qtip right away before all the aromatics evaporate.

The only drawback is that the smell of it sticks around. There is no way to get rid of it except time.

A heavier oil will resist being thrown off but one thing I have
noticed recently on some old fan bearings is that thoroughly cleaning
the old worn bearings with a solvent before adding new oil helps a
lot.

Hell thanks everyone for all the good info !

I am having a similar issue with the fan motor on my ancient Tek 317. As a previous poster said : "nice, this fan is really quiet ! " ... thought exactly the same about my 317 when I first got it (having no prior experience of any classic Tek), then after an hour of running, suddenly the fan would accelerate significantly, as if it decided to switch second gear so to speak, to what seemed to me like a more plausible speed...

I dismantled the motor, lubricated it with fine machine oil, exercised it by hand for several minutes.. didn't seem to make much difference to me.

So I was about to give up and replaced it with a modern/plastic fan, while hunting for a replacement fan, if such a thing can still be found these days, that is...

So before I give up, I will try to first clean it as much as possible before oiling it, then exercise it a lot more than just 5 minutes by hand.

Should this fail anyway, can this motor still be found, do people sell these things ? If I can't find one coming from a 317 scope, was this motor also used in other classic Tek scopes (or some other kind of instrument, who knows), or maybe not exactly the same, but something close enough, that would be mechanically compatible ? I assume all 300/500 scopes, being of the same era, had similar/close designs and that there must be some degree of interchangeability between models ?? That would definitely increase my chances of finding a suitable motor.

According to the service manual, the part number for the motor in the 317 is 147-001 if that's of any help.


Regards,


Vincent Trouilliez

[me in the previous message] > " So I was about to give up and replaceD it with a modern/plastic fan, while hunting for a replacement fan, "

Oops, typo, the 'D' should not be there.. I have NOT yet replaced it with a modern fan...

Scary how one tiny little typo can make you look like you are saying nothing less than the absolute opposite of what you actually meant ! ... :-/


Vincent Trouilliez