AO compound: model, year, repair ideas?

[toomanyhandles]

A little while ago when a colleague learned I liked microscopy, I was given this scope. Looks like university surplus, so probably got bounced around a bit, last serviced in 1993 per stickers.
Overall it looks and feels OK, not as dirty internally as externally by far, usable condition oil objective.

But using that objective is hard, as the fine focus has a problem. I think oil was my colleague's primary goal so playing with this then stopped... I was told the fine focus drifted. What I see with a little playing is that fine focus only works if I turn both knobs in conjunction, else it slips and nothing moves. I left it for a few hours the other afternoon and I didn't notice it dropping out of focus on its own....

Any ideas on repairing are welcome, it seems like something needs tightened but getting into it, I'm not sure best where to start on the focus assembly. I have dug into some small mechanical things (clock assemblies, like the barograph in the background that needs some TLC) but I consider myself ham-fisted. Or a service manual to help take a informed look inside (even if not for this model, just as a reference point?)

I do not see any specific AO model on it.
The illuminator plastic has underneath the scope: illuminator 10363 (almost the only plastic on the unit)
stamped in the metal of the scope in one place are the numbers: 908269. I couldn't find any reference to this number as an AO number, maybe it is a serial#.

Thank you for your thoughts-

Brian.

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[PeteM]

It's an A.O. Series 10. Decent scope.

My recollection is that a couple of wave washers tension the fine focus. If you carefully disassemble the screws (one from each side) in the center of the fine focus you should be able to clean out the old grease (possibly hardened), replace it with a suitably lube, and tighten the screws (and compress the wave washers) enough to engage the fine focus.

[KurtM]

Yes, that's a very decent scope, especially for the price. It even has a POL turret intermediate tube (between the stand arm and bino head), which will be super nice once you discover the joys of simple polarization. If you desire to keep and use this scope for the usual pond water type of stuff, get a 20x objective for it and it's guaranteed you'll be glad you did.

[toomanyhandles]

That's great, thank you both.
How backwards compatible are the objectives on these, as long as I avoid anything on ebay that is "infinity", could I be OK? How to tell where the cutoff is (look for catalog numbers near the ones on the objectives I have? : )

I am also looking for a manual / catalog with accessory part #'s for this, so I can use that to find what will be compatible.
I spent a bit googling but not found a good one yet.

Oh, and what's the likely age range on this one?

I have 2 more older scopes I will be posting, both mirror'd light source ones. One I have used a lot the other like this I'd like to find out more about it and get it into shape. I really appreciate this forum, I have read back in time a bit and that has helped a lot.

Brian.

[DrPhoxinus]

That AO uses infinity objectives but they are shorter than the standard 45 mm length. 37 mm.

Kurt is right that a 20x is ideal for pond specimens

Gerard

[dtsh]

That's great, thank you both.
How backwards compatible are the objectives on these, as long as I avoid anything on ebay that is "infinity", could I be OK? How to tell where the cutoff is (look for catalog numbers near the ones on the objectives I have? : )

It is my understanding that the 10/20 series and the 110/120 series can use the same objectives.

[toomanyhandles]

It does look like I have a mix of both heights on the scope today.

Where might I find the serial # on this?

The number 908269 that is stamped into one part of the scope frame doesn't match the serial number range listed here:
https://user.xmission.com/~psneeley/Per ... oscope.htm and the link to
https://user.xmission.com/~psneeley/Per ... Window.pdf

and omgosh, so much information to sort thru. Including the list of accessories and manuals for multiple years of scope.

[hans]

It does look like I have a mix of both heights on the scope today.

I think those are all 34 mm parfocal objectives. The lower magnification ones just have longer working distance as illustrated here:
https://www.microscopyu.com/microscopy- ... cal-length

[apochronaut]

Your microscope is most lIkely from about 1970 +- year or two. Three of the objectives are infinity corrected planachros. There will be a cat.# stamped on each objective barrel as cat. 1017, for instance. You have a cat. 1017 4X .12, cat. 1019 10X .25 plus a 40X objective harkening back to the late 60's. The first planachro objectives made for that microscope in about 1967 looked exactly like the achromats, narrow barrels with 7 colour coded rings at the bottom. One difference was that the barrel was polished chrome rather than brushed chrome and the bottom of the barrel had a bevelled edge rather than a coved edge. Your yellow objective looks like an early cat. 1023 40X .66 planachro. The red objective is probably a cat. 1079 100X 1.25 achromat. All of the objectives are 34mm parfocal, a distance that is measured from the objective shoulder to the point of focus, not the length.

You have 15X cat. # 184 eyepieces. You will want to get a set of # 176 10X W.F. eyepieces as well. For this reason I can't concur with Kurt's suggestion that you look for a 20X objective. They are hard to find, they are popular and expensive anymore. With the 15X eyepieces you will have 150X anyway, and with a 9mm working distance, so the 20X won't provide you much , especially if you cannot find a cheap one.

The first thing to do regarding the tight focus, is to remove the screws rhat hold the focus inspection plate ( top if the arm) and watch the mechanism as you turn the focus knobs. This will give you an idea where the stiffness is. Ninety percent of the time with those it is dried lubricant , where it has the greatest surface area against the mechanism, causing the most resistance. Sometimes there is universally dried lubricant but not always because AO used different lubricants for different applications. I see a lot of lubricant along the shaft dtying and this really drags the mechanism down. I have most of the focus parts if you end up needing any.

[toomanyhandles]

Thank you Hans and apochronaut. I really appreciate your looking and the estimate on when this was made.

The objective that made me think one might be different total focal length was/is the one with the yellow bands. I can't seem to get a good image from that one, but I think/hope it just needs cleaning. If I adjust the stage a little I get a slightly better result, DOF doesn't improve but the slice that is sharp is just a little better (my eyesight is crap but as a result I've learned to pick and choose a bit on what I can rely upon). That said, work is so busy right now I was just checking the objectives against a sharpie pen writing on a blank slide....so that's a pretty slim DOF as a test....

Cat # on that yellow ringed one is:
#1116 45X .66 infinity

100X is #1079 oil 1.25 and it is a little crapped up and I am waiting new immersion oil to try it with once I clean.

the other objectives are as apochronaut mentioned, I should have just listed them all in the first post rather than making folks peer into photos.

-->I really appreciate your guidance on how to find and clean the biggest problem with the focus gearing.

Probably I should just plunge into tasks like this but after all this time my inclination is still to think about it for ages rather than just trying things, I worry too much about making things worse. This has been waiting attention for about 10 months while I thought about it. Is there anything I _should not do_ when looking into the grunge on the fine focus?

Thanks for thoughts!

[apochronaut]

I was hoping my eyes were seeing correctly and that your yellow objective was an older #1023. The original 45X objective for that microscope was a #1078, released as part of the original series 1076 10X, 1077 20X, 1078 45X and 1079 100X. Later, as the use of that microscope ramped up for blood counts in the 1960's they decided to develop an objective that had a longer w.d. and was corrected better for the #1 .40 haemocytometer cover slips. That one is the 45X .66 #1116 objective.
It is a good all around 45X achromat, with decent planarity. Due to it's slightly longer w.d. it is particularly useful for amateurs and students who might make thicker than is normally acceptible samples or be using prepared slides with thick cover slips. If you mic. prepared slides, the cheaper ones and some older less expensive ones are over 30microns. The 1116 handles those with ease and delivers .66 N.A. performance. Many longer working distance objectives of that magnification made until recently were .55 or thereabouts.

To loosen up your fine focus. Here are two basic lubrications you can do to start off. They are usually an assistive lubrication on those scopes . The lubrication points there, won't be responsible for your problem but they need to be attended to by the time your microscope is as old as yours is. It takes about 10 minutes for each.

Put the microscope on a cloth or towel on a bench or work table. Get a # 2 Philips screwdriver and a 9/16" allen wrench or key.

1) Unscrew the thumbscrew that fastens the head or a lower accesory to the arm. In your case it is a filter accessory. Remove it along with the head. Be careful not to tip the eyepieces tubes down, the eyepieces will probably fall out with gravity if you do. This exposes the arm cap or top cover plate and the front bolts that fasten it. Using the 9/64" hex or allen wrench remove the 3 hex bolts that surround the circular dark grey forward section. Using the #2 Philips screwdriver loosen the philips screw at the rear. Lift off the cover. This exposes the upper arm mechanism that raises and lowers the attached nosepiece.At the rear you will see an I or dumbell shaped brass device. This is a floating ball retainer that rides along the ballrace between the vertical focusing pillar and the two outer vertcal ballraces. During the process of focusing this ball retainer rides up and down with the ball bearings. As the lubricant dries, the balls rotate slower and one side can become retarded agsinst the other. This can eventually cause problems if it gets bad enough.
Rotate the coarse focus topside backwards to raise the focus to it's maximum. This will lift the ball retainer and expose about 1/2" of the two outside ball race channels. You will see a brown grease at the top of each. Drop one drop of preferably a heavy machine oil into each channel. If 3 in one is all you have, then it will do.
Turn the focus knobs forward some and REPLACE THE COVER. Leave the head off still.

2) Adjust the coarse focus knob until the nosepiece centering screws are about 1/2 cm. below the frame or the objective yoke. This puts the focus in about it's mid range. You will be turning the stand upside down. With some stands, there is enough wear or imperfect adjustment of the focus mechanism that turning it upside down while at a focus extremity will allow the travelling arm to drop out. It isn't hard to get it back in but that circumstance is best avoided. Put the stand on it's side with the bottom facing you. All of the illuminators used for the series 10 were fastened to the underside with two large pan head Philips screws. Using the #2 screwdriver or bit, remove them. This allows you to remove the illuminator. The centering screws for the field diaphragm at the front inhibit the illuminator from dropping straight out. Rather than removing them to facilitate that, you lower the rear section of the illuminator, then draw the illuminator forward until the adjustors clear the legs of the horseshoe. This saves having to recenter the field diaphragm. Removing the illuminator exposes the lower section of the hollow column, through which the focusing shafts and attached mechanisms go. You will see a large worm gear. The gear shaft works in two large bronze bushings situated in the casting of the column.With one focus knob facing down, drop two drops of the same oil used above into the shaft bushing interspace and work the coarse focus knob back and forth about twenty times. Then turn the microscope over and do the other side the same.. Replace the illuminator.



Put the microscope on it's feet and try the fine focus. The fine focus is the same focus as the coarse focus, it is just a micrometer clock gear that acts slowly on the coarse focus. Sometimes the coarse focus will be a bit stiff but the fine focus very stiff both caused by a problem in the coarse focus. If lubricating the coarse focus has had no effect on the fine focus, then you will have to dig a little deeper but try those lubrication points first.
It is possible to overdrive the fine focus on those, that is why they have a slip clutch for each knob. That makes the fine focus very stiff but the knobs usually slip on the shaft.