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Just bought a working (I can see both traces, on-board calibration seems ok
on both channels) Tektronix 454 with a Scope-Mobile Type 200C cart.

I havent attempted the adjustments in the manual, and didnt even look a the
calibration section as I dont have the equipment and not even sure cost or
who can even calibrate this old of a scope.

I mostly was wanting a cheap scope to help repair some 70's, 80's arcade
circuit boards that I have (ie. sound circuits, vector boards (oscope in
x-y mode, etc).

I love how this scope looks, but not sure how long I would be able to use
it due to its age.

Any known components that fail on these often, or should I just plan on
using it while I can and hope for the best? I'd like to keep this running
as long as possible.

Sincerely,
Brian

Where do you live, maybe one of our members is close and can come and give
it a once over (for a beverage of choice or similar)?

Regards,
David Partridge

Brian:

yes, keep it and enjoy.

There's a 500pf 16kV door-knob capacitor in the EHT which sometimes fails, but it's not nessecarily going to go pop in your 'scope.

Other than that, the Nuvistors, being thermionic valves, do wear out, so you could inverst in a couple of spare 8393's when you spot some at a sensible price.

John

I live in the St Louis, Missouri area, would be interested if there are
others in this area from the group as well.

Here is a picture of the scope


Brian

Thanks for the recommendations on the EHT capacitor and the Nuvistors.
Brian

I had a great time fixing up two 454s in the late Summer. One I had owned for some time but had been left unused for a few years, needed a replacement for one of the 0.015uF 2.5kV capacitors in the high voltage box. Not an easy job to dismantle the box with many silver bearing solder connections but once done the scope is almost like new.

The other one was bought very cheaply for spares and had numerous faults but all easy to fix. A shorted capacitor in the high voltage driver section, a few plug in transistors and one power transistor to change. The only difficult job was replacing the trigger tunnel diodes but that is done now and this scope is also working like new. I have given them an approximate calibration against a cheap DDS signal generator and they are easily brought back to spec.

So my story is that I love the 454s, they may well fail with age but parts are easily obtained (apart from the aforementioned tunnel diodes) and they are a delight to use. There is a wealth of expertise to help you with any problems, the biggest difficulty is that if you have a dead scope, almost the first thing you need to fix it is a working scope!

Have fun with your 454,

Roger

That's a really solid scope.

+1 on the nuvistors and you might want to keep your eye out for
replacement tunnel diodes. They're getting a bit scarce, but you can
find them for a reasonable price if you're persistent and patient.
I have a couple spares, but the scopes haven't needed them.

When I was refurbing my 454 early this year, I had to track down a
number of problems and it amazes me that you can still find NOS parts
for it. Ebay is your friend here.

I also ended up with a cheap tube tester so I can at least check
emissions on the nuvistors.

Let's see, on mine I had a bad power transistor in the HV PS,
a bad reed relay in the bandwidth limiter switch, a bad transistor
in the single sweep control and a broken contact on the AC/Gnd/DC
switch for one channel. After fixing all that, it only needed very
minor tweaks to get in spec. Not bad for a 50 year old scope.

You can get a service manual free online, but you may want to find a
printed copy. The scans are OK, but the fold out schematics are
worth the cost of a printed manual.

If I had a choice, I'd like the larger screen on the 454a, but really,
you can't go wrong with this scope.

--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows