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HP 181A vintage scope - shipping fail

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TerraHertz:
For completeness.



This is going in the hallway display case. Now I know what 'flood guns' actually look like.

The worry I had about the delaminating '1971 flexible pcb' attached to the CRT, won't be a problem. Easy to improvise a replacement if needed on a new (old) CRT since it's just soldered to the three leads from inside the front of the CRT.






One of the traces had apparently failed in the past, and someone had bypassed it with a bit of wire that is definitely cut out of an old rubber-insulated mains cord.

And now, from the Twilight Zone...
The scope is still spitting out small shards of glass when I give it a shaking. Today, during one of those shakes this fell out.



WTF? It's totally not from the scope. I'm pretty sure ICs like this did not exist when the scope was built circa 1971. HOW did it get in there? I've seen small 'drop-ins' inside stuff before. Bits of clipped wire, small components, etc.
The scope has been worked on in the past - that wire, a small shield plate missing, etc.
But in what kind of work environment does some 24 pin IC (a ROM?) get dropped into an open old scope?

Anyone recognize the HP part number?

ebastler:
Seems like a 24-pin DIP IC "5081-3018" is used as the control IC in the 1805A vertical amplifier:
http://hparchive.com/Manuals/HP-1805A-Manual.pdf

Edit: Two of them, actually, one per channel. Shake some more and you should find the other one!  ;)
See the parts list (page 38 in the PDF) and the schematic (page 62).

rsjsouza:

--- Quote from: TerraHertz on March 19, 2022, 05:31:05 am ---
--- Quote from: Stray Electron on March 18, 2022, 02:47:24 pm ---  Yeah, that shipping box looks much too small for a rack mount scope. Especially for some thing as heavy as HP. Was there ANY padding in it? 

--- End quote ---

Padding at the sides and around the brackets - Poor but better than nothing.
Padding at front, rear and top and (fatally) bottom - virtually none.

Some more unpacking pics. This one:



--- End quote ---
It is indeed unfortunate your situation; I can see how leaving the front handles unpadded would easily transfer any mechanical impact to the frame and consequently to the more fragile parts of the equipment. I hope you get a good replacement CRT.



--- Quote from: TerraHertz on March 20, 2022, 09:51:26 am ---The worry I had about the delaminating '1971 flexible pcb' attached to the CRT, won't be a problem. Easy to improvise a replacement if needed on a new (old) CRT since it's just soldered to the three leads from inside the front of the CRT.

--- End quote ---
Interesting you mentioned that. A related discussion.
https://www.eevblog.com/forum/repair/old-hp-181a-storage-scope-repair/

TerraHertz:

--- Quote from: ebastler on March 20, 2022, 10:02:09 am ---Seems like a 24-pin DIP IC "5081-3018" is used as the control IC in the 1805A vertical amplifier:
http://hparchive.com/Manuals/HP-1805A-Manual.pdf

Edit: Two of them, actually, one per channel. Shake some more and you should find the other one!  ;)
See the parts list (page 38 in the PDF) and the schematic (page 62).

--- End quote ---

Thanks!
The 181AR scope contains not one single IC, just transistors.
Dealing with the smashed CRT, I took out the plugins and stashed in a cupboard. I have the plugin manuals but hadn't looked at them yet. One is an 1805A (as you knew.) With their covers on the plugins looked about the same vintage as the scope.

But no, this 1805A was made in 1978. It has very few ICs but two of those 24 pin analog things.



You can just see the remaining white ceramic IC in the pic above.



One present, one AWOL. This is looking at the bottom of the module. That the impact could knock one of these out of the socket...



The loose one back in place. It's quite hard to get all the pins in those tiny sockets.



Looking at the module, more bad news. One of the push switches has a broken shaft.
Also one of the V/div selectors turns freely. No detents.



Date codes on ICs. This plugin was made in 1978 or later. Hence the ICs.

Not much more I can do on this scope until I find a CRT. When I continue I'll start a new thread in Repairs.


TerraHertz:

--- Quote from: rsjsouza on March 20, 2022, 11:12:00 am ---I can see how leaving the front handles unpadded would easily transfer any mechanical impact to the frame and consequently to the more fragile parts of the equipment.
--- End quote ---

No no. The scope was lying flat in the box, and the box was dropped flat. Front handles and rack brackets did have some folded cardboard padding (not much) but that wasn't involved.
In that photo I'd lifted the scope up and sat it on its rear, just to show how little padding lay under it.



--- Quote ---Interesting you mentioned that. A related discussion.
https://www.eevblog.com/forum/repair/old-hp-181a-storage-scope-repair/

--- End quote ---

Ha. Yep it just disintegrates. Also possibly this one had arced in the past, hence previous repairer cuting away part of it. Burned? Bodgy design, bodgy repair.

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