Author Topic: Tektronix 466 Scope Issue  (Read 2111 times)

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Offline alco539

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Tektronix 466 Scope Issue
« on: May 10, 2016, 12:10:36 pm »
A couple of years ago someone gave me a Tek 466 scope. It initially powered up and appeared to work just fine. However before I could really use it and check it out good the 15 volt power supply either died or something is pulling it down. Any ideas where to start looking or where to get the proper schematic for it. I was able to find the ones for it's cousin the popular 465 which was pretty close but not exactly the same as this is the storage version of the 465.

Thanks for any assistance.

Jimmy
 

Offline AF6LJ

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Re: Tektronix 466 Scope Issue
« Reply #1 on: May 10, 2016, 12:41:54 pm »
Sue AF6LJ
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Offline MrSlack

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Re: Tektronix 466 Scope Issue
« Reply #2 on: May 10, 2016, 12:45:43 pm »
AFAIK it's pretty much the same piece of kit as the 465. If it's not a B rev, the service manual is here for the 465: http://www.opweb.de/en/model.php?id=2968 - the other versions of the SM appear to be incomplete.

Diagnostic procedure on these (I have three 465B's and am juggling them a lot):

1. Check the rail voltages using the test points on the board. The range and tolerance is in the service manual. You can check ripple with a half decent multimeter set on AC volts.
2. Check all electrolytic and tantalum caps for shorts. There's a nasty wet tantalum at the base of the A4 board that likes to explode as well as some on the vertical board that like to snuff it.
3. Check all bridge rectifiers on the A4 board.
4. Check the MC1458 op amp at the base of the A4 board.
5. Check the power transistors at the rear of the unit for shorts.

The 15v rail is referenced on the 55v rail so make sure that's working first.
 

Offline alco539

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Re: Tektronix 466 Scope Issue
« Reply #3 on: May 10, 2016, 12:57:12 pm »
Thanks guys. I haven't needed it since I got it so I really haven't been too motivated to look at it. I now have a need for it and wish I had looked at it earlier  |O Hopefully I will get i nailed down in the next few days.

Thanks again.

Jimmy
 

Offline alco539

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Re: Tektronix 466 Scope Issue
« Reply #4 on: May 16, 2016, 05:23:53 pm »
The problem turned out to be a shorted tantalum cap on the 15 volt rail. I swapped it for an electrolytic I had and it is working beautifully now.

Thanks for the help.

Jimmy
 

Offline tautech

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Re: Tektronix 466 Scope Issue
« Reply #5 on: May 16, 2016, 08:48:31 pm »
Jimmy
For the sake of completeness for anybody finding this thread it'd be a good idea to list the cap part # and the values.  ;)
Avid Rabid Hobbyist
 

Offline alco539

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Re: Tektronix 466 Scope Issue
« Reply #6 on: May 16, 2016, 10:43:37 pm »
No problem,
I should have included that information in the first place.

C3462, a 6.8ufd tantalum on the Vertical Preamp board.

Jimmy
 
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Offline MrSlack

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Re: Tektronix 466 Scope Issue
« Reply #7 on: May 17, 2016, 07:45:29 am »
Glad to hear a positive outcome :)
 


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