Reunion with my first scope after 32 years

[robrenz]

When I was 27 I was doing some digital design and builds for a engineer friend.  One was a multi channel digital rotary cam (before they were commercially available) for food processing equipment.  I told him I needed a good scope and if he bought it I would trade work to pay for it.  So I got  a new Tek 7603 with a 7B53A and 7A26 7A18 amp IIRC around $5000.00 in 1980. Yeah I know, extreme severe overkill for what I was doing but it sure was cool.   I ended up not doing enough work to pay off the scope and he gave it to his son.  No hard feelings, I kept a lot of other stuff from the projects and eventually dropped out of the electronics scene.

Fast forward 31 years and I stumble on the EEV blog. Dave rekindles my love of electronics.  In the next 18 months I build a pretty nice lab and am learning a lot.  I want to do some low level scope measurements and buy a 7A22 differential amplifier. That triggers the thought, wouldn't it be cool if I could get my original scope back.  I google the name of the son and give him a call. Turns out his brother is the one that got the scope and he says he will email his brother to see if he still has it.  No response for almost a week and I see a 7603/7B53A mainframe that looks like a good deal on EBay that I don't want to miss so I buy it also.  (Neither one has arrived yet).  Today I get a call from the brother that had the scope.  He still has it and is very glad to send it to me, he wont let me pay for it or the shipping.  He never used it and thought about Ebaying it but never bothered but could not bring himself to throw it out.  So my first scope that might have 10 or 20 hours total run time is coming back to me after 32 years. Amazing

[SeanB]

Well done.

[DavidDLC]

Prety nice !

[robrenz]

I will post some pics as soon as it shows up.

[ElektroQuark]

We want a review!

[SeanB]

Want a picture of the reunion.........

[Hypernova]

Oscar bait story right there folks.

[robrenz]

My son and I were just joking about doing a video with my slow motion run toward, and the embrace of my old scope friend with Vangelis chariots of fire music in the background.

[M0BSW]

That's heart warming, I don't ever want to hear your selling it,because this was meant to be ,according to my wife who read this, shes's always right and I have permission to say so.

[robrenz]

What is the opinion about powering up this scope that has probably not been on for 20 years. Should I do the variac with gradual increase to reform the electrolytics?

[ivan747]

Imagine it worked perfectly fine. The guy  1 post above me would be perfectly right.

[robrenz]

The 7A22 from EBay showed up today,  This is what sparked the whole thing. Looks like it is in perfect condition.  This is quite a bit of kit. Differential input, 1MHz BW, 10µV/div to 25V/div. 100000CMRR, adjustable LF & HF filtering, internal offset voltage, 1000V common mode voltage and offset capability but limited to 500V because of the probe rating.  I cant try it yet because the EBay 7603 isnt here yet.

A good sign is the fuses on the board and the spares are not blown. I have never seen a fuse wire that small, I had to look at it under 30X to even see the wire.  What amazing construction especialy those machined adjustable capacitors.

[billclay]

Wow, look at all that gold!

[HLA-27b]

What a reunion! Some catching-up to do now...

[robrenz]

If anyone thought this was just a story, both scopes showed up in todays UPS. 


My scopes serial number is aprox. triple the ebay scope so a lot younger. It is very dusty and needs a good cosmetic and electrical cleaning. I was going to get a variac and do the slow cap reforming deal.  Instead I said a prayer and plugged it in. No magic smoke after 30 mins run time. everything works and no busted switches or knobs.

The Ebay scope was a lot cleaner and it showed traces and the readouts on the listing but still said not functioning.  When I fired it up it just had a wierd squiggle around the center of the screen. Finaly figured out the beam finder button was stuck in. After that everthing was ok.  The bonus is the 7D14 525MHz counter timer plugin in the left vertical slot.  Quite a few busted knobs on the 7A18 amp but it still works.

My first scope that returned home on the left.  "Ishmael"   from Ebay is on the right.


My original


Ebay


My original has the 1.22cm division screen. 12.2cm x 9.76 viewing area.  Starting to sniffle.


Ebay had the 1cm division screen 10cm x 8cm viewing area


My original operation and service manuals.  Ok.... I am crying now


(3) hp 10X probes (2) 1X hp probes

[SeanB]

And all those indicators are incandescent lamps, with the graticule illumination working perfectly as well.

[robrenz]

Started cleanup and restoration of the scope and plugins 32 years of dust inside and outside. I am going to post that stuff HERE on projects, designs and technical stuff page Product Reviews, Photos, and Discussion .

[Mechatrommer]

(i didnt catch this thread i guess it was during my october busy days)

this is a nostalgic event. $5000 and 32 years of waiting, i think its worth it, in that time history has polished one of the finest "machinist" ever known i also have about similar (but crappy version) of nostalgic event, when i got out of school i thought i want to continue learning ee, but then only after 10 years, i got reunioned with what i should have 10 years ago... an oscilloscope! now i got my own crappy one DS1052E those analog you posted Rob, is an eye opener, 10uV/div gosh! thats something impossible with my scope. your insight and "hi-standard-view" can certainly teach me in someway. i believe your coming back to ee and reunion is not "zero knowledge" on your back, you already got some "karate skill belt" back on those years.

i should have seen and realize the way they do it (the 7A22), what do they call it, hybrid pcb? no ground plane nothing, just few polylined traces (signal path?) going around with big big through hole components. few days ago i thought i want to write a "novel" entitled "the friend of the enemy", where people keep mentioning use ground plane, use ground plane! where particularly in differential probe app, ground plane actually is a CMRR killer! if not laid carefully, i learnt it the hardway. and those metal finned/stripped trim capacitor (i believe) are just scarry awesome.

thanks for this thread and pictures Rob! 

[Ed.Kloonk]

Is this anything like getting back an old girlfriend? Will it be the same after another man has had fun with it for so many years?

Knobs will be noticeably saggier and input jacks will be well worn.

[Mechatrommer]

at least she still got the red button there, thats the most important part. according to the report, she got not much used by the previous owner so she still good. and based on the other psu thread that lead me here, she still has the 10uV/div detail "tenderness" spec which undoubtedly can give a satisfaction sensation to her "true lover". but how can you equate a machine and a woman? those are "different"

[TerraHertz]

I'm glad this thread resurrected. I wasn't here in October, but this is a lovely story. You're very lucky.
I never even got close to owning one of the Tek scopes in my early years, just used them at work.
Oh, but I _wanted_ to own one, so badly!

Only decades later, I discovered I could buy from the USA via ebay. Now I have a fair size collection of Tek 7000 series stuff, and still love them. Especially the rackmount ones.

Some of the plastic parts are getting rather brittle, you have to be gentle with them.

There's one chronic problem, that may not happen when you run them on 110V. The mains input filter uses a type of polyester cap, I recall rated about 400VAC, 0.01uF? Something like that. They have clear plastic molded cases, that go a bit yellow and crack with age. Anyway, they seem to almost all develop shorting whiskers through the film or something as they age. Any 7000 series scope, that's been left off for years, then turned on with 240VAC mains, is likely to either immediately or in the first few minutes have a nasty case of "PFHUT!" and a very distinctive smell. The caps arc internally till the fuse blows (can be a few moments) during which time the polyester gets converted to a vile stinky, sticky smoke, that's a pain to clean off nearby components. Those caps are 'replace on sight' nuisances.

[poodyp]

Because I didn't have enough cool things on my list of stuff I want but don't really need.

Now I'm looking at all the different plugins... it's like collecting all the transformers action figures...

[T4P]

I'm assuming it's not a X2 rated cap right?

[robrenz]

i should have seen and realize the way they do it (the 7A22), what do they call it, hybrid pcb? no ground plane nothing, just few polylined traces (signal path?) going around with big big through hole components. few days ago i thought i want to write a "novel" entitled "the friend of the enemy", where people keep mentioning use ground plane, use ground plane! where particularly in differential probe app, ground plane actually is a CMRR killer! if not laid carefully, i learnt it the hardway. and those metal finned/stripped trim capacitor (i believe) are just scarry awesome.

Thanks for the kind words Mecha,

Remember that the 7A22 is only a "within 10% of 1MHz" bandwidth amplifier. If I open the Preamble 1855 100MHz BW amplifier I bet there will be some ground planes.

[TerraHertz]

All these fascinating 'old scope' threads!
https://www.eevblog.com/forum/projects/tektronix-465-repair-and-restoration/
https://www.eevblog.com/forum/reviews/hp-1741a-oscilloscope-restoration-project/
https://www.eevblog.com/forum/chat/reunion-with-my-first-scope-after-32-years/

But they're all in different places. Maybe this forum should have a category for 'restoration of classic test gear' or something like that?

Are there any other great threads on restoring old scopes?

And... with all these wonderful stories of brilliant success, perhaps for contrast I should tell my story of shame, with a Tek 7104 mainframe. It's really embarrassing and sad. But not over yet! Just put aside for a while.