Electronics > Repair

Tek 465 repair and restoration


Hi, my first post on EEVblog.  Just won a successful bid on E-bay for what looks to be a pretty clean Tek 465, picture shows no vertical or horizontal deflection only bright dot in center of CRT.

I used to work in a cal lab back in the day when Tek 535's and 545's were the ones we saw most often.  I don't remember very many problems with these units other than replacing vacuum tubes that did not meet spec and just general calibration. I'm sure I did, but I don't remember having to replace and re-solder any components to those beautiful (Coors) ceramic stand off strips. We were told that each silver/solder joint was bead blasted with crushed walnut shells to achieve that  smooth satin finish.

Anyway, back to Tek 465, I understand that the Tantalum caps be bad by this time after 30 plus years... I plan on recapping the power supply and replacing the Tantalum caps, wherever the may be through out the rest of the scope.  Any suggestions for modern caps to replace the tantalums?

Thanks, Love this forum.  great bunch of folks. :-+

Welcome to the forum.

In the "Repair " board there a list of links to find any manuals you might need.
The first post also has a link to a Tek troubleshooting pdf that is good to have.

The full bridge rectifiers in those units are known for failing.. I even had one fail right in front of me after I removed the case to repair the other that failed.
Replacing the large electrolytic caps is a given, I had a small cap fail shorted, but it wasn't tantalum. I'm not sure if they have any tantalum caps in them.

The tunnel diodes are esd sensitive, and the only replacement is those Russian tunnel diodes on ebay.. iI have a 475 that had all four tunnel diodes fail shorted for some mysterious reason.. i have 10 tunnel diodes that are rather close to the Tek spec, but it will still require a lot of fiddling with resistors to make the switch.

Be sure to post some pics! I like restoring older vintage equipment also.

First of all, just make sure it wasn't set in X/Y mode.  I've picked up more than one piece of equipment that was marked as "for parts or repair" and the only problem was the controls weren't set properly.

Hopefully they turned the intensity down so it didn't burn the phospor.

It's not a bad idea to replace the filter caps; they're getting a little old.  The common failure mode is for them to fail open dumping huge amounts of ripple into the supply rails.  That generally doesn't hurt anything, but the scope behaves very strangely, depending on which supply fails.  If the caps are good though, I'd hesitate on replacing them.  It's fairly easy to damage the PCB getting them out.  The best way to do that is to disassemble things to the point where you can cut the lugs on the cans from the component side.  You can then remove them without the problem of having a huge heatsink attached.  That's a fairly large pain to do though.

The first order of business on a 465 repair is to check the power supplies to see if they're in spec for voltage and ripple.  I'd do that even if you plan on replacing the filter caps.

You can find original spec tunnel diodes, but you have to scrounge hard for them.  I haven't had to replace any yet, but it's always a possibility.

It may be worthwhile to keep your eyes open for another 465 parts mule.  Some of the parts are getting difficult to find in NOS.


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