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Old 2nd Feb 2016, 5:43 pm   #1
davieradio
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Hi. My tusty Techtronics 465 has just failed, looks like a PSU fault.

On the diagram there are a a load of fuses in the the secondary of the mains transformer. There is an EHT fuse somewhere.

I can only see one 1 1/4" glass fuse, where are the other ones?

Dave
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Old 3rd Feb 2016, 10:30 am   #2
davieradio
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Default Re: Tektronics 465 Scope

still looking for a manual with layouts most of the downloads don't have the board layouts
Dave
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Old 3rd Feb 2016, 11:35 am   #3
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Default Re: Tektronics 465 Scope

They may be fuses, Jim, but not as we know them...

Some fuses look like 1/8 watt resistors, some look like small ceramic cylinders with two pins out one end... about 10mm diameter.

David
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Old 3rd Feb 2016, 2:22 pm   #4
tony brady
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Default Re: Tektronics 465 Scope

It would be worth looking at the tants on the 15V rails as they can short. My 468 had this problem and the supply is very similar
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Old 3rd Feb 2016, 2:53 pm   #5
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Default Re: Tektronics 465 Scope

Dave, what kind of 465 model do you have exactly?
The net gives you manuals in example minimum 4 versions:
465/A-B-M and DV44 Meter-Modul...
Other tema, that Tektronix didn`t publicated PCB(layouts), but you can find component population drowings in all me knowed SMs.
Greetings Karl
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Old 3rd Feb 2016, 2:57 pm   #6
Skywave
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Arrow Re: Tektronics 465 Scope

The tall aluminium can electrolytics are favourites for PSU problems. However removing them for subsequent testing (and then possible replacement) is not an easy task. But with perseverance, it can be done. You do need a really hot iron, though.

Al.
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Old 4th Feb 2016, 8:27 pm   #7
davieradio
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Default Re: Tektronics 465 Scope

my 465 is a standard 465 the flat chassis mounted power transisor near the Eht suppy has very low votage, it is one of three flat pwr transistors I think this is the 5V supply but not sure
still need a circuit with layouts I can't find a circuit or layouts of the boards

Dave
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Old 4th Feb 2016, 11:30 pm   #8
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Default Re: Tektronics 465 Scope

Dave, you can find a 30MB file here_or here_I think my copy is the same...
Check please the circuit & placement matrix between pages 235-240.
On my copy is part locator relative bad to read, but +5V Transistor is a Darlington_Q1556,hase a code for parts/grid locator=3F. On page 236, find it please over C1562, the left side "big electrolytic" in a group of 5 pcs...
I wish sucessfull rep!
Karl

Last edited by karesz*; 4th Feb 2016 at 11:36 pm.
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Old 7th Feb 2016, 6:35 pm   #9
davieradio
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Default Re: Tektronics 465 Scope

HI , thats a great manual , I notice the EHT inverter has 25v on it and oscillates but the neons used a shunt regulator do not light
I suspect the EHT transformer, it looks difficult to get to located under the interface board fixed with nylon screws still tying to find the EHT dide I think it may be inside the metal can with the transformer
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Old 8th Feb 2016, 10:32 am   #10
tony brady
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Default Re: Tektronics 465 Scope

the EHT multiplier is with the transformer and it's hard to get at. when you remove the Y board be careful to unsolder the 2 resistors from the Y1 &2 attenuators.

if you have a suitable meter there is a -2450V test point on the pcb
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