Electronics > Repair

Tektronix 465B - Won't turn on...

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Hello!!... My name is David, and as you can see i'm a Chilean, so i'll do my best effort to be clear explaining the problem.

One year ago, i bought a Tektronix 465B, it was working very good until someday won't turn on... so i started to see what happen.

The first thing i saw was the fuses... the primary fuse has blown, so i thought that the issue could be something from the power suply.

i started to measure all semiconductors, they are ok.
in another forum, users told me to change the capacitors, because they are the first problems, when i did it, it still blowing the fuse.

So i think you can give me a hint on whats happening here....

If someone wants to write in spanish, i suggest to write in both languages so other people can understand and stay in tune.

Thank you, I hope you can understand my english.

Welcome to the forum.
Get the Tek scope trobleshooting pdf from the first post in the Repair board.


Here is the link

The filter caps fail open, for the most part, so that was not a likely problem.

The bridge rectifiers can short though, so you should check those.

If those are OK, one of the power supplies may have shorted to ground.  Check the resistances from the low voltage test points on the main board to ground (with the scope off, of course) to see if you can isolate which supply has the problem.   Once you find out which is the cause, you can start tracking down the problem.   The problem might be in the power supply itself, or further down the line.  There are a few bypass caps around, one of those may have shorted.  I think there are a few tantalums as well and those are a possilbility.  You may have to end up taking things apart a bit in order to isolate the problem to a board.

It's relatively easy to track down a shorted part if you have a milliohm meter once you have the general area located.

It shouldn't be too hard to track down.  I'll take a completely dead unit over one with an intermittent fault any day.

Hello and Thanks for the answers...

I've been reading the Troubleshooting manual From Tektronix and i think its interesting.
I made all things that have been explained in the book as posible, i don't have much equipment to do the test, so it's a little hard for me to make troubleshooting.

I think one of this days i'll check the resistances from the low voltage test points. (The scope is always Off due to the blown fuse of the primary transformer).

So i'll be keeping you updated about this.

Thank you all.. I apreciate your answers.



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