Tektronix 7603 with 7B53A and 7A26 plug ins

[Refugee]

I have just acquired one of these huge well built scopes and it almost all there with the beam finder button missing and two knobs not original.


I have powered it up on full mains and it looks like dirty switches with them all being intermittent.
They are the gold pad with gold finger kind so oil free cleaner. I have Ambersil FE10 and would like to check that it will do although I am pretty sure it will work just fine.
There are at least 10 screws to undo to get to the switch on the 7B53B plug in so that the timebase can be got working again.
The attenuators also need to be done in the two 7A16 plug ins.
If that does not fix the on screen displays there will have to be even more switch cleaning.
The manuals are huge PDFs. The 7B53B manual has proved to be illusive but the A variant is out there.

[Nick]

The Tektronix 7xxx-series are beautiful 'scopes - I had a 7904A for years with those plugins (amongst others).

Eventually decided it was just tooooooo big and the PSU had developed "the tick of death" (a classic fault), so I moved it on...

Loved it, though - I was sponsored through my EE degree by STL at Harlow and my workbench there had a 7904 on it - it was wonderful having one back again - loved them. STL is regarded as the birthplace of optical fibre communications and was part of ITT at the time.

This old photo of my test bench from 2003 shows it (and some other Tektronix bits) - bench is a bit different now... (bit more modern)

[Refugee]

What a wonderful workbench all be it a little too tidy for me to feel comfortable there.
My 7603 does have a little bit of noise on the Y amps so there will be one or two capacitors to replace when I get in a bit deeper.

[AlanBeckett]

Yes, it's the 4 Plug-in 7000s that are 'Huge', apart from the early Valve Models. I've only got a 7704A, plus others.
I can't find any reference to 7B53B on Bama or tekwiki.

Alan

   

[Refugee]

The 4 plug in models are even more huge than mine.
Well I have powered it up and the tube is bright and as reported by the vendor there is something wrong with the timebase.
I have downloaded the 7B53A manual as a close guide for the 7B53B and it does not have an awful lot of differences.
Faults found so far are the time base only has three speeds with a little bit of variation on the settings in between the steps that work. There is a -50V supply that does not do much apart from feed a reference to the time base switching. I will have to get the covers off the frame and check it before I go in any further.
There is a bit of noise on the Y amps so capacitors in the power supply need to be checked too.
The scale lamps are not working so if these are NLA the old ones will have to be stuffed with LEDs.
The on screen display will also need to be looked at. There are little bits missing from the trace when the switch is on so some of the logic is working but not the character generator.

[Nick]

There are loads of sources for original spares around - Sphere Research is one of the main ones see http://www.sphere.bc.ca/test/tekparts.html for loads of spares (used them several times), but there are several other suppliers. I have also used Qservice (in Rhodes of all places!) several times for Tek spares - very helpful people - http://www.qservice.tv/vpasp/default.asp

There is also a specialist Yahoo group, "TekScopes", where several of the original Tektronix engineers hang out - its is an extremely useful and very active resource with a lot of knowledgeable and helpful members - I used it extensively when rebuilding/repairing my 7904A, 2465A & 2430 'scopes. Definitely worth joining - https://groups.yahoo.com/neo/groups/TekScopes/info

[AlanBeckett]

The on screen display will also need to be looked at. There are little bits missing from the trace when the switch is on so some of the logic is working but not the character generator.

That's normal. There will be litte bites missing from the Trace as the Logic writes the Display. There's an internal Switch to change over to 'Sync' mode so that the Display is only written after the Sweep. The downside is that you don't get any Display if the Timebase isn't running.

Alan

[AlanBeckett]

You're not a million miles away from me. If you get down this way at all you could borrow a couple of Plugins to speed things up.
Also, I may go to see Joe in Sheffield in the not too distant.

Alan

[Nick]

I'm surprised by this - I never had any problem with the on-screen-display flickering - it was always as steady as a rock.

Lot of threads about it on the TekScopes forum...

[AlanBeckett]

7603 Manual.

   
   

Alan