Repairing an Analog Oscilloscope

[scoobey82]

I was wondering if anyone knew what could be wrong with an analog oscilloscope when the tracer won't show up at all. The oscilloscope is an older, discontinued Tektronix 2445B. Thanks




_____________________
Scoobey Doo

 

[zachtheterrible]

Maybe its not plugged in?

Is it powering on?

 

[ljcox]

I was wondering if anyone knew what could be wrong with an analog oscilloscope when the tracer won't show up at all. The oscilloscope is an older, discontinued Tektronix 2445B. Thanks




_____________________
Scoobey Doo

There are many possible reasons. For example, the EHT could be faulty, beware of shock and you need special equipment to measure its voltage.
There could be a fault in the Y amplifier such that it is causing the trace to be deflected off the screen. Does it have a "trace finder"? If so, then you should see a trace if you press it - assuming the fault is as I said.

It could be a fault in the timebase. Or a fault in the Horizontal amplifier, etc.

Do you have a circuit of it? If so, it should specify the typical voltages that should be seen at various points.

Start with the obvious such as a failure of a power supply.

If you have a circuit, scan or take a photo and post it so we can assist.

 

[scoobey82]

Yes it is powering on. I am thinking it has to do with something around the CRT. The screen will not work at all. Thanks for the advice, and i haven't taken it apart to look at it yet so i can't show a picture of the circuit yet. I will look into the suggestions listed here, but if anyone has anymore, please share them. Thanks again!

 

[Dean Huster]

An older, discontinued scope? Geez, you make me feel old. That product came out after I left Tektronix. Makes the 465 and 7904 on my bench look like relics!

The "analog" scopes weren't that difficult to repair. As the scopes got "newer", Tek started adding digital control to the analog functions to include readout parameter generation, digital display of delay time and provision for auto set-up. Because of that, the malfunction of the digital control can cause total scope shutdown as easily as can a defective analog section or power supply!

Regardless of the type of scope, whether tube, transistor or integrated, analog, hybrid or digital, the first check is ALWAYS the power supply. Just because it appears to "light up" doesn't mean that all of the supplies are working properly. Most Tek scopes of the non-DSO variety have LOTS of power supplies. e.g., the 7000-series has +130, +50, +15, +5, -15 and -50 not to mention the high voltage and PDA accelerator voltage.

Dean

 

[scoobey82]

Didn't mean to insult you, Dean!! Thanks for the info. I will look at it as soon as i get time.