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HP 1741A oscilloscope - restoration project

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coppice:

--- Quote from: David Hess on September 01, 2014, 01:22:45 pm ---
--- Quote from: coppice on September 01, 2014, 10:51:23 am ---I think the 1741A was the only really satisfactory analogue storage scope ever made.
--- End quote ---

Why do you say this?  I really like some of the Tektronix analog storage oscilloscopes with the notable exceptions of the 464/466 and operating any of their variable persistence tubes in bistable storage mode.

--- End quote ---
The Tek scopes had a number of problems, but the bleed alone was enough to make them pretty awful. I always thought that was rather odd, as they had the bleed totally controlled on their graphics terminals. You could turn one of those off on Friday, and on Monday morning the same 4096x3072 resolution image was still there in its full glory.

David Hess:

--- Quote from: coppice on September 01, 2014, 01:32:29 pm ---
--- Quote from: David Hess on September 01, 2014, 01:22:45 pm ---Why do you say this?  I really like some of the Tektronix analog storage oscilloscopes with the notable exceptions of the 464/466 and operating any of their variable persistence tubes in bistable storage mode.

--- End quote ---
The Tek scopes had a number of problems, but the bleed alone was enough to make them pretty awful. I always thought that was rather odd, as they had the bleed totally controlled on their graphics terminals. You could turn one of those off on Friday, and on Monday morning the same 4096x3072 resolution image was still there in its full glory.
--- End quote ---

I have never had a problem with this on the ones I have used but maybe I do not understand the issue.  I find the stored image retention on my 7834 rather annoying actually.

Maybe this is an aspect of their storage transfer CRTs which allow very fast single shot writing rates?

tggzzz:

--- Quote from: tautech on August 30, 2014, 09:04:10 pm ---Just checked, they are definitely hex grub screws that hold the timebase knobs on.
2 sizes, 1/16 and 0.050.
the 1/16 is easy to acquire, the 50 thou not so easy.

--- End quote ---
The hex keys have just arrived and the 050 fits nicely. Thanks.

But the grub screw is frozen in position sufficiently tightly that I don't want to break the key or strip the head :(

I've doused the screw in WD40, and will see if that has any effect. Then it will be a light machine oil or penetrating oil.

If that doesn't work, are there any standard techniques I could use?

SeanB:
Try tapping gently on the hex key to shock the screw in the shaft, and if that does not work take a soldering iron and heat up the hex key and thus the grub screw to loosen the oxides that are holding it, or loosen the locking compound. Heat it till it just starts to smell, then try to turn it loose, and if no turning try to tighten then loosen. Then hit it with freezer spray to thermally shock it and it should come loose.

David Hess:

--- Quote from: tggzzz on September 03, 2014, 02:52:05 pm ---I've doused the screw in WD40, and will see if that has any effect. Then it will be a light machine oil or penetrating oil.

If that doesn't work, are there any standard techniques I could use?
--- End quote ---

My ordered list of methods to remove set screws is:

1. Applying light machine oil and waiting.
2. Using a soldering iron to heat the screw.
3. Sacrificing the screw and replacing it once it is out.

I have a special 1/16 hex key where I filled down the flats on the end to make it into a hollow ground 0.050 hex key so it fits very tightly and will not strip the screw.

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