tektronix 465 repair

Lee Gleason

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Dec 20, 2014, 5:03:55 PM12/20/14

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I have a crusty old TEK 465 I saved from going into the garbage a few
years back. Finally got time to pull it off the shelf and see what's going
on with it.

I was told it was completely dead and not repairable when I salvaged it -
I thought, I'll be the judge of that. Initially it was stone dead - no
trace, no lights, no fan nothing. I found a 1.5 A fuse (F1419) blown, and
when replaced, it would blow again immediately. None of the panel lights or
the fan would come on, and all the power supply voltages were low.

I found one bad capacitor that was grounding the +15, when it started
smoking (some faults are easier to locate than others). Replaced it and then
found another cap, C1419, that was shorted that was blowing F1419. Replaced
it and now the lights and scale illumination and fan come on.

When I press the beam finder, I get a large dot flash and then nothing.
Letting off the beam finder and adjusting the controls for a normal trace,
I noticed that the whole screen is sort of illuminated. If I slow the sweep
way down, I see that a dim 3/4 inch wide by whole screen tall bar goes
across the screen, at about the rate you'd expect on the slow sweep
settings - so that looks like the HV and the time base stuff is more or less
working.

I'm guessing I have some sort of vertical amplifier problem. Before diving
back into the schematics, I thought I'd ask, anyone ever seen this symptom
before?

--
Lee K. Gleason N5ZMR
Control-G Consultants
lee.g...@comcast.net

Phil Hobbs

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Dec 20, 2014, 5:22:51 PM12/20/14

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Re-capping the whole thing would be a good start, I expect. I have a
475 that I'll have to do that to one of these days.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

amdx

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Dec 20, 2014, 5:24:01 PM12/20/14

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There's a good TEK yahoo group that might be helpful.

Mikek

mike

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Dec 20, 2014, 5:24:08 PM12/20/14

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I'd go check all the caps. Over the last few years, I've had more and more
caps fail in tek stuff. Originally was the teardrop tantalums, but more
recently, all types.
I don't have a schematic handy, but if you can check the bleeder
resistors in the HV supply, I'd do that. There should be HV test
point that you can check with a normal multimeter.

Tom Miller

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Dec 20, 2014, 6:43:02 PM12/20/14

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"Lee Gleason" <lee.g...@comcast.net> wrote in message
news:5495f247$0$13196$882e...@usenet-news.net...

I would recommend going through the adjustments section of the service
manual. That will offer you a chance to find any out-of-spec parts. The Tek
manuals are very complete and include a theory of operation section that
will answer most questions.
Pay attention to the ripple/noise specs on the power supply test points. The
+55 volt rail serves as the main reference for the rest of the supplies.

Regards

mike

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Dec 21, 2014, 12:06:58 AM12/21/14

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That's a good idea, but concentrate on getting the numbers close by
fixing busted stuff. I'd recommend against randomly tweaking stuff
in an attempt to fix hardware problems.
That assumes that the previous owner exercised similar restraint
when he tried to fix it.

jurb...@gmail.com

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Dec 21, 2014, 11:40:54 AM12/21/14

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Are the voltages on the vertical plates close ?

RobertMacy

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Dec 21, 2014, 11:45:50 AM12/21/14

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On Sat, 20 Dec 2014 15:03:27 -0700, Lee Gleason <lee.g...@comcast.net>
wrote:

Did you ask the TEK group?

<TekS...@yahoogroups.com>

I saw some detailed info go by there, often.

Jeff Liebermann

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Dec 21, 2014, 2:00:01 PM12/21/14

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On Sat, 20 Dec 2014 16:03:27 -0600, "Lee Gleason"
<lee.g...@comcast.net> wrote:

>I'm guessing I have some sort of vertical amplifier problem. Before diving
>back into the schematics, I thought I'd ask, anyone ever seen this symptom
>before?

These may help:
<http://www.eevblog.com/forum/projects/tektronix-465-repair-and-restoration/>
<http://www.spurtikus.de/basteln/repair/tek465/index.html>

--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Sofa Slug

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Dec 23, 2014, 1:25:53 PM12/23/14

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On 12/21/2014 10:59 AM, Jeff Liebermann wrote:
> On Sat, 20 Dec 2014 16:03:27 -0600, "Lee Gleason"

> wrote:
>
>> I'm guessing I have some sort of vertical amplifier problem. Before diving
>> back into the schematics, I thought I'd ask, anyone ever seen this symptom
>> before?
>
> These may help:
> <http://www.eevblog.com/forum/projects/tektronix-465-repair-and-restoration/>
> <http://www.spurtikus.de/basteln/repair/tek465/index.html>

Great Links!

Here's another that may be useful (see the first two items listed under
"Documents"): <http://www.hakanh.com/dl/>

Happy Holidays, everyone :)