Author Topic: Tektronix 2465A... help did I blow it up?  (Read 382 times)

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Offline GASMANTopic starter

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Tektronix 2465A... help did I blow it up?
« on: September 13, 2024, 05:52:54 pm »
Hi All.  New here to the forum. But not too new to electronics so I should have known better.  I had my Tektronix 2465A connected to the antenna out put of my ham radio transmitter and began transmitting.  Scope seemed to tolerate it for a while (sure had a nice wave form).  After I realized what was going on I stopped transmitting. It happened a second time and now the 2465A is not so happy.

On start up it gives me an error code of Test 05 Fail 24.  I am not sure what that means -- .  I can clear that code by pressing the A/B Menu button and the scope will continue to boot up.  However; both Ch 1 and 2 fail to trigger on a simple 10mV 10kHx  sine wave from my signal generator.  Also when I switch scales the horizontal axis jumps way off scale. (Same thing happens on both Ch 1 & 2) .

Did I totally fry the Scope... or is there hope.  Thanks in advance for your help.

Gasman
 

Online tggzzz

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Re: Tektronix 2465A... help did I blow it up?
« Reply #1 on: September 13, 2024, 06:06:40 pm »
Hi All.  New here to the forum. But not too new to electronics so I should have known better.  I had my Tektronix 2465A connected to the antenna out put of my ham radio transmitter and began transmitting.  Scope seemed to tolerate it for a while (sure had a nice wave form).  After I realized what was going on I stopped transmitting. It happened a second time and now the 2465A is not so happy.

On start up it gives me an error code of Test 05 Fail 24.  I am not sure what that means -- .  I can clear that code by pressing the A/B Menu button and the scope will continue to boot up.  However; both Ch 1 and 2 fail to trigger on a simple 10mV 10kHx  sine wave from my signal generator.  Also when I switch scales the horizontal axis jumps way off scale. (Same thing happens on both Ch 1 & 2) .

Did I totally fry the Scope... or is there hope.  Thanks in advance for your help.

Gasman

Did it work before that happened?

Was it in 50ohm or 1MHom mode?
What voltage/wattage did you apply to the input?

The service manual (available on TekWiki) defines the meaning of the test result. From memory (possibly faulty) I suspect you have a capacitor leakage on the A5 board. FFI see the other 2465 threads
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline GASMANTopic starter

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Re: Tektronix 2465A... help did I blow it up?
« Reply #2 on: September 13, 2024, 06:26:02 pm »
Thanks for the prompt reply.

1.  It was working fine before hand (and seemed to be working fine for a while afterwards so I thought I had escaped disaster and maybe the two events are unrelated)

2.  It was in 1 M ohm Mode

3.  I am sure at one point the output briefly hit 30 to 40 watts

As I have never dug into the workings of the scope (although it sounds like I am about to) what is the A5 board.  I was recapping an old transmitter and testing it out when all of this occurred.  I will dig into the prior treads regarding the 2465A.


 

Online tggzzz

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Re: Tektronix 2465A... help did I blow it up?
« Reply #3 on: September 13, 2024, 08:13:49 pm »
So 40W into 50ohms is Vrms=sqrt(40*50)=44V. Vpeak is thus 63V (or 126V if it wasn't terminated in 50V). Ought to check that's OK at whatever frequency you were using. If course if you were using the scope to dissipate 40W in its internal 50ohm terminator, that might well be toast.

Possible mistake of mine: ought to check if the 2465A has the problematic capacitors on the A5 board; it might be only the 2465B. Even if it is marked as a 2465B, you might care to check the A5 board, since apparently there's an infamous fleabay seller that <cough>upgrades</cough> 2445Bs. (I have a 2465, and that has neither the A5 problem nor the infamous Dallas battery-backed RAM).

If the Dallas battery hasn't given up the ghost yet, you are lucky. It contains the calibration constants, and you don't want to lose those!

You will probably want to recap the main PSU board sometime.

Plenty of instructions to be found on gurgle. Many of those results are links to this forum.
« Last Edit: September 13, 2024, 08:17:58 pm by tggzzz »
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 


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