ALC68 strip down & clean - Help please

[smogthemog]

I have a rather mucky ALC68 and PSU - it's seen a fair bit of nightclub use in it's life by the look of things. I wish to strip it down and give it all a good clean up, de-rust and re-spray. The PSU isn't much of a problem but the head may well be. I wish to dismantle it all and wondered if it is viable to do so and if it is then what precautions do I need to take so as not to damage anything?
I am particularly worried about the glass tubes in the second photo below and how they connect into the brass mounts with the mirrors in (I know the terminology isn't there just yet but I am getting there ) Will it all strip down and re-align easily and is it really worth doing it - OR - should I just clean it up as best as I can with everything still in place and leave it well alone?

It does work by the way at the moment - quite well

PS - I like a challenge

Thanks

[smogthemog]

A few more pictures for those old gas lovers:

[stanwax]

I assume they are brewster stems - and the copper shroud and tube will be to keep the atmosphere within the shroud controlled (ie clean). I am also assuming that the laser therefore has external optics - cant have external brewsters and optics
You will need to be very careful not to snap the stems off while removing cleaning storing (while you clean everything else) and reassembly.
Following this you with need to realign from scratch which though not difficcult needs time patience and some ingenuity. You have a working alc60 right? You can use this as your alignment laser though you will need to make some means of adjusting its height and pitch so it shines cleanly through the bore of the 68. There is a great detailed account on this in SAMs FAQ. I have used this method to realign my SP168 and it worked a treat afterwards - better than ever before .
I would say however if its working and performing well then leave the tube and optics alone. Just dust out any crap in the fans airducts and fins. If the output is diminished over what you should expect then it will be worth the time and efforet to clean and realign.

Rob

[smogthemog]

Thanks Rob for the quick reply. I have an afternoon free in my shed and have got it stripped to where the photos show it now but didn't want to go any further without seeking advice.

I would really like to remove the 2 aluminium air inlet cans from around the 2 center coils as they look like a dogs dinner, they need cleaning but I guess this is going to mean a total strip. Also the laser has a cooling problem as it wont run for very long at 2W before going out on over temp. It looks to me like some of the cooling fins require re-bending to allow better air flow and possible further cleaning once removed. The EHT igniter in the center has been epoxied in place and quite a bit of epoxy has ran down the fins causing further blocking. Also it looks to me like the distance between the coils differs from front to back. The distance between the back 2 coils and the front 2 coils is a lot wider. The front 2 coils therefore will not cool as well as the back 2 as the air won't be able to circulate as well with the smaller gap.

I would like to have as many as the steel parts as I can bead blasted.

Would I be able to use a green or red pointer as an alignment tool as the ALC60 is a little cumbersome?

[stanwax]

Yes you could use a red or green pointer but what you need most of all is a really tight clean beam - just like the beam of a gas laser - I use a hene. The problem is that you really want to go down the centre of the bore (which is quite narrow) without grazing the sides as this will make it harder to see when you have it right. A pointer will have a shitty beam profile and may just make the job a nightmare. Get the alignment laser as far away as is practical - there is a limit to this as you need to see behind the 68 when you are adjusting the alignment laser so you know whan the beam is bang on through the centre. For me this was tough with a tube that is in the order of 1 metre!
You could set up a web cam and screen where you are adjusting the alignment laser but thats more faff. In reality my lasers were only about a foot appart when I first did it - but they recommend more distance as it makes it more accurate.
I know its no help today....but if you wanna borrow my hene and its jig that allows it to be adjusted for height and pitch - its not pretty or sophisticated but it sure as hell does the job.

Rob

[p1t8ull]

I would say however if its working and performing well then leave the tube and optics alone. Just dust out any crap in the fans airducts and fins.

Yeah, I wouldn't strip the head if it's working ok at the moment Jim, you can clean the fins and rectify any minor damage to them quite easily without pulling the tube from the resonator. If the problem is that it keeps overheating, is it possible the cooling fans are just not be up to the job?

If you're real keen to get stuck in, how about having a play with that old 60x head you had at UKLEM first? It's essentially the same beast, just a smaller version.
Those copper mounts you mention are removed along with the tube after sliding them back onto the glass stems. The mirror holder assy can be removed from the outside to make this easier if you're doing a full strip . They have low outgassing "O" rings sealing them up and they can become quite stuck to the glass stems, so be very careful if you do go for it.

[smogthemog]

Do the copper mounts just pull off from the ends of the glass stems?
There seems to be a slight vacuum in there - does it need to be re-gassed in any way once these are removed?

I think I am going to go ahead with it as I really would like to get this head all nice and cleaned up. If I knacker it then so be it but I will take EVERY precaution to not do that believe me.

Thanks Simon

[stanwax]

They should just pull off but as Simon says (???) the 'o' rings may have glued to the glass so careful with that stem smog. I would take the fixings off and gently twist one way then the other - the give in the 'o' rings will allow you some movement then beyond that you should be working on the rubber to glass bond. When this goes you should be good to slide it off.
Dont be tempeted with that can of WD40 to help it along!!!

They will not have vacuum or gas in them, the rubber tubes should go back to an expansion bulb that will allow breathing with temperature but without allowing the nasty outside world in

Rob

[smogthemog]

Got them all off and have started stripping it all down to send all the bits for bead blasting.
The rubbers were ok to remove and not stuck at all - Luckily

[aijii]

Also the laser has a cooling problem as it wont run for very long at 2W before going out on over temp

I don't know of any ALC68s that can actually run at 2W CW. They are rated to like, 4 Watt or something but this is peak only. If you want any kind of life out of that tube I'd suggest you don't run it CW above 1 Watt absolute maximum if it's in good working order and ambient temperature is low...