Test Equipment Anonymous

The first project. Fix this mess.




Replacement out of a junk unit 465. Same P/N except the wiring is different. Swapped over the wiring. And yes, that outer shaft is slightly bent. Fixed it.



Success.



I did not have the correct Slope knob in my stash. Which is not surprising since that knob always gets broken on 400 series scopes. The P/N is 366-1280-00 and I checked Ebay with no results. Checked QService and they have it listed but no stock. So I took the knob off the B Trigger since the A Trigger is most often used. Hopefully one day one will turn up. In the meantime a successful repair.



Next project is to fix my Hakko Soldering Station.

Well done. It's a disgrace the way these beautiful things have often been treated.

Another thing frequently damaged is the time base knob, which is quite a complicated thing and sticks out a way. Very often the transparent bezel is cracked or is starting to crack. The careful application of superglue can stop it getting worse.

Is it practical to have the trigger knobs 3D printed? I see there are people on Ebay selling 3D printed feet for 400 series scopes. Mostly the feet on those scopes are brittle and have begun to break up. Other scopes, such as Hitachi, just don't seem to have those problems with feet. The Ebay feet are quite expensive in my view, around £20 a set, so I haven't bought any.

Zenith wrote: ↑Wed Jun 28, 2023 9:11 pm Is it practical to have the trigger knobs 3D printed?

Almost certainly; the question is what material to use.

If you want a smooth shiny off-white hard knob with fine detail, then SLA would be a good choice. I've used it for a 4x5 squirrel cage collet, and a handle with a thread for example. Stunningly cheap at DirtyPCBs.

If you wanted something with a little more plasticity and a "sandblasted" finish in a number of colours, then one of the nylons would do.

I see there are people on Ebay selling 3D printed feet for 400 series scopes. Mostly the feet on those scopes are brittle and have begun to break up. Other scopes, such as Hitachi, just don't seem to have those problems with feet. The Ebay feet are quite expensive in my view, around £20 a set, so I haven't bought any.

I must admit to be suspicious about the shear strength of PLA/ABS feet like that.

Zenith wrote: ↑Wed Jun 28, 2023 9:11 pm Well done. It's a disgrace the way these beautiful things have often been treated.

Another thing frequently damaged is the time base knob, which is quite a complicated thing and sticks out a way. Very often the transparent bezel is cracked or is starting to crack. The careful application of superglue can stop it getting worse.

Is it practical to have the trigger knobs 3D printed? I see there are people on Ebay selling 3D printed feet for 400 series scopes. Mostly the feet on those scopes are brittle and have begun to break up. Other scopes, such as Hitachi, just don't seem to have those problems with feet. The Ebay feet are quite expensive in my view, around £20 a set, so I haven't bought any.

The mangled control was caused by Yours Truly while fitting up the new lab.

I don't see how a 3D printed knob would be a practical solution when it requires set screws to secure it to the shaft of the pot.

What's next Mike ?
More multiplier burn ins ?

MED6753 wrote: ↑Thu Jun 29, 2023 1:05 am

Zenith wrote: ↑Wed Jun 28, 2023 9:11 pm Well done. It's a disgrace the way these beautiful things have often been treated.

Another thing frequently damaged is the time base knob, which is quite a complicated thing and sticks out a way. Very often the transparent bezel is cracked or is starting to crack. The careful application of superglue can stop it getting worse.

Is it practical to have the trigger knobs 3D printed? I see there are people on Ebay selling 3D printed feet for 400 series scopes. Mostly the feet on those scopes are brittle and have begun to break up. Other scopes, such as Hitachi, just don't seem to have those problems with feet. The Ebay feet are quite expensive in my view, around £20 a set, so I haven't bought any.

The mangled control was caused by Yours Truly while fitting up the new lab.

I don't see how a 3D printed knob would be a practical solution when it requires set screws to secure it to the shaft of the pot.

That depends on the material. Fortunately, it is a pot not a switch, so little force is required to rotate it and therefore grip it.

Some materials are sufficiently high resolution that you can "machine" a thread in them, albeit one larger than in your knob. Others are sufficiently flexible for a self-tapper.

Here's a 2mm pitch thread and a 24x5 squirrel fan collett that is attached by a screw. In the latter case the standard small bolt self-tapped the SLA.
If I couldn't find a pukka knob, I'd spend a couple of hours with OpenSCAD and £5 to get a couple made from SLA.

tautech wrote: ↑Thu Jun 29, 2023 3:08 am What's next Mike ?
More multiplier burn ins ?

Next major project is install of a repaired HV assembly in a third Type 547 and then a restoration.

The missing knob issue has been resolved. I went through my parts units again and it turns out that a 485 has the same control but uses a slightly smaller diameter and style of knob. Turns out they fit perfectly on the 475A. I don't care if there's a mismatch between Trigger A and B controls.

I have a dream that one day I will go to a minor swapmeet and having swept the tables and seen nothing of interest, I'll do the second round looking under the tables and see under one of them, stacked within each other, four front covers for 400 series scopes, the topmost full of Tek knobs and a small aluminium foil package, which turns out to contain tunnel diodes, back diodes and step recovery diodes, plus a few hybrids, all of which test good. On the other side there will be a box (the cover from an R1155), full of the DF stuff from 1155s, (normally just stripped and thrown away), and the name plates from various receivers - also routinely stripped and discarded - and a few other goodies.

£15 for the lot? Done!

Should that happen, I've no doubt that in a spirit of unaccustomed generosity, I might find myself sending a Tek 475 trigger knob pair winging toward you, as fast as jet fuel could carry it.

Nothing in this involves the known laws of physics being broken.

It's good to have dreams. But don't bet the farm on them coming true.;

I'll have to rummage to find the original Frustion360 file; it was one of my first prints on the Tevo Tornado so very long ago...

mnem


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