Oscilliscope repair

[jrz126]

I just bought another oscope off ebay to repair the one I have with the broken CRT.

The one I bought has a few problems...according to the auction, it fails the self tests for CCD, PA, and Trigs.

The scope that I have now passes (well it passed before it broke) all of the selftests.

Am I better off just swapping the CRT or should I try to fix the problems on the one that I am about to recieve (maybe by swapping circuit boards)?

I do have the service/repair manual, so I should be able to figure it out.

I'm a noob when it comes to ocsope repair, so Im hoping there are some of you out there with some experience

 

[JimB]

I would swap the tube.
Your first scope was working until it was dropped, the most likely thing to break is the tube.
So, swap the tube and see what happens.

JimB

 

[1st Mil-tech]

Yep just replace the CRT, less time and aggravation and no calibration would be needed.

 

[jrz126]

You're positive that I dont need to recalibrate? I emailed somebody from tektronics awhile back and they said I would have to.

 

[Nigel Goodwin]

You're positive that I dont need to recalibrate? I emailed somebody from tektronics awhile back and they said I would have to.

Changing the CRT will obviously change the calibration, but it might even be closer than it was before - so don't worry about it!.

Bear in mind you can only read a scope scale to a fairly poor degree of accuracy, so if the scope is slightly out it doesn't matter that much.

 

[1st Mil-tech]

of course you would get that reply from Tek, silly me, their interest is only in the equipment working to specs. Oh no! you mean there's a, what price did you say,service charge?

Don't get me wrong, I used to work for em and they are a quality oreinted company, but you may be able to buy a refurbished one for less than the calibration costs.

The beam adjust controls are analog so whats to calibrate?

 

[Dean Huster]

OK, "1st Mil-tech", your little pic has brought back a flood of old memories, but I can't sort them out. That was a crystal radio, right? Who made it? As I recall, it was just a tuner and what appear to be other knobs aren't?

Dean

 

[jrz126]

The service manual has a 'display adjustment' section. There are quite a few adjustments to be made...like on the time base display board there are 9 pots...Integrate time, Vert vector comp, Horiz gain, vertical gain, vert spot wobble...ect.

Will l have to adjust these? (these are what I was referring to when I was talking about calibrating)

Fed-ex says it should be delivered tomorrow

 

[Nigel Goodwin]

The service manual has a 'display adjustment' section. There are quite a few adjustments to be made...like on the time base display board there are 9 pots...Integrate time, Vert vector comp, Horiz gain, vertical gain, vert spot wobble...ect.

Will l have to adjust these? (these are what I was referring to when I was talking about calibrating)

Don't worry about them! - bang the tube in and see how it works, if they do need adjusting?, what have you got to adjust them against anyway?.

However, most adjustments probably won't be required, and it will probably be close enough as it is.

 

[jrz126]

Just got it all put back together and it looks pretty good, all of the tests pass.

It feels kinda weird tearing into something that you paid $200 for only a few minutes after it is delivered to your house.

 

[Joel Rainville]

It feels kinda weird tearing into something that you paid $200 for only a few minutes after it is delivered to your house.

Feels kinda weird? I guess it all depends on your income...

I would've been terrified to put a screwdriver in that oscilloscope. :lol:

Glad it worked for you though 8)

 

[Nigel Goodwin]

It feels kinda weird tearing into something that you paid $200 for only a few minutes after it is delivered to your house.

What!? - you paid $200 for a non working scope?, even worse, one that wasn't even complete!.

 

[jrz126]

Well I originally paid $6.25 for it. (I got it from a junk room at work...the going rate for electronics is $0.25 per pound). Then it fell and the CRT broke (Snowblowers may look like a good oscope stand, but they really arent).
They also have 2 of those sweet LCD type 4 channel scopes (the TDS series) in the junk room. but they are holding onto them for parts.

I have an internship at GE transportation, so I have a decent income for a college student, but it doesnt feel like I do because almost all of my money goes towards paying for that hell.