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tektronix 465 repair

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.gleason@comcast.net
Reply to
Lee Gleason
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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
Reply to
Phil Hobbs

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.

Reply to
mike

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

Mikek

Reply to
amdx

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

Reply to
Tom Miller

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.

Reply to
mike

Are the voltages on the vertical plates close ?

Reply to
jurb6006

Did you ask the TEK group?

I saw some detailed info go by there, often.

Reply to
RobertMacy

These may help:

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

Great Links!

Here's another that may be useful (see the first two items listed under "Documents"):

Happy Holidays, everyone :)

Reply to
Sofa Slug

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