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-   -   Tek 465 repair (http://www.diyaudio.com/forums/equipment-tools/228105-tek-465-repair.html)

buzzforb 18th January 2013 05:14 PM

Tek 465 repair
 
Tek 465 inputs stopped working. Not showing any waveform. Not the probes. aNy ideas where to look?

mrmodemhead 18th January 2013 09:49 PM

Both channel 1 and channel 2 dead?

A few ideas:

Try punching the Trig View button a few times. Sometimes those contacts at the rear end of the vert pre-amp board get nasty. Also, if you do get a signal displayed when you engage the Trig View, then the vertical deflection amp must be working and the fault will be ahead of it.

Check the connections on both ends of the delay line. They go into Peltola connectors on the PCB.

Check power supplies, especially on the vertical preamp board. Those dipped tantalum caps are famous for taking out power rails.

dacen 18th January 2013 10:51 PM

I was almost certain that I had the service manual for this one, and that was the case. Itīs for SN B250000 and up. If you want something from this manual scanned and sent to you by E-mail I could certainly assist you. Actually itīs a thick book with the complete documentation

buzzforb 18th January 2013 11:01 PM

Thank you both. I have read about the contact issue. Just hopinf for some trails to follow, as iam sure itis going to be interesting.

Loudthud 20th January 2013 01:23 AM

You want the 465 {nothing} manual. The 465M or 465B are not the same. I don't have the correct manual, but I have the other two.

I'm assuming you have just one bad channel. The would localize the problem to before the channel switch (1,2,alt,chop,add)that is before the delay line and deflection amp.

Do you have what seems like normal operation of the vertical position control on the affected channel? That would be a good sign.

The signal goes from the input connector through the AC/DC/Gnd switch, then optionally through passive attenuators controlled by the Volts/Div switch. Then it gets to the first JFET, usually a TO-99 cased dual part with one side setup as a Source follower the other as a current source. There is usually a 470K resistor paralleled by a 0.01uF cap in series with the gate as protection. If the signal gets that far, all is good with the attenuators but you need to check all the positions.

Once the signal gets that far it probably goes to a Tek made unobtainium IC where the position control DC is summed in. Some scopes have the 1-2-5 gain change at this point.


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