New scope

[zachtheterrible]

So I nabbed this little beauty off ebay for a whopping $76! Which means its bound to have problems. **broken link removed**
It's a tektronix 2232 100MHZ digital/analog scope- the best of both worlds!

Problem 1: Look at the picture that I've included. I'm sure someone with any kind of experience will recognize this problem right off the bat. Does the screen need to be degaused or something? If it's permenant, oh well, it's still a sweet deal!

Problem 2: None of the digital portion of this scope works. I figured that would probably be a pretty simple fix, most likely involving a loose connection or some kind of power supply issue. Is there any advice to be given or should I just open 'er up and see what I can see?

 

[jrz126]

It may be something alittle more complicated than a loose connection. My 2430A was having some problems, it would just freeze during selftest. Occasionally it would turn on, but it would freeze while I would try to use it and I'd have to push the acuire button...
Anyways, I had another 2430A sitting around from when I had to repair the CRT...(It may seem like a good idea at the time, but a snowblower is not a solid oscilloscope stand). So I just started to swap parts, it turned out to be a couple of the main ICs were bad. Luckly they were just held in by the heatsink so I didnt have to desolder anything.

It can really hurt to pop the cover off either. If there are some easily removable IC's, maybe try removing those and putting them back in.

Also, definitly try to locate a service manual for it. It should have a good troubleshooting guide as well as an entire schematic of the scope.

Good luck

 

[Dean Huster]

"Degauss" and "oscilloscope" should never be used in the same sentence together as you NEVER have to degauss a scope unless it's an early 1980's unit (scarce) that used a color electromagnetically-deflected "picture tube" rather than a standard oscilloscope electrostatically-deflected CRT. Your picture suggests that you may have a dimple in the scan expansion mesh (there's both vertical and horizontal anomolies), probably caused by something loose inside the CRT which in turn, was probably caused by someone dropping the scope at some time. The only fix is a new CRT which will have to be from some "hangar queen" off ebay if you don't want to buy a new one from Tek for $600 or more. Otherwise, if you don't want to spend any more on the scope, you'll have to mark the bad area on the face of the CRT with a grease pencil or Sharpie and ignore anything in that area.

Dean

 

[jrz126]

Ouch, that sucks about the CRT. Zevon8 gave me this link: https://www.sphere.bc.ca/test/tek-crts.html when I was fixing my scope. It looks like that CRT is used in quite a few scopes too.

I wonder if the scope was dropped during shipping? The trace looks great in the auction pic.

 

[JimB]

Curious.

Two threads in the past few weeks with scopes which give weird displays for no obvious reason.

JimB

 

[Hero999]

If it got damaged in the post and isn't the seller's fault (because they packaged it properly) then what's the procedure?

Is it the seller's responsibility to make it isn't damaged in transit or is it the buyer's?

Can either party recover the cost from the shipping company?

 

[zachtheterrible]

I'll probably just snag another CRT. Is there a part number or anything for the CRT?

I actually do have a repair manual for the scope, but the troubleshooting guide really isn't too helpful. Guess I'll just crack it open and see what I can see

Gotta go, just got my new ipod!

 

[Rolf]

Problem 1: Look at the picture that I've included. I'm sure someone with any kind of experience will recognize this problem right off the bat. Does the screen need to be degaused or something? If it's permenant, oh well, it's still a sweet deal!
QUOTE]

The problem with repairing oscilloscopes is that you need another scope (with a HV probe) for your trubleshooting. The Tectronics manual is a must after you have looked for any obvious signs of damage, they are expensive, check Ebay for a used one or Googel for a dealer in used test equipment.
Questions, is the distortion very much the same on all sweep freq's. The focus of the trace is not great in the picture. Could you post another picture with about one cycle per cm. Is the focus knob about in the center? I dont think the CRT could be dammaged to cause that type of sweep, you might have some fluxiation in the HV powersupply or the sweep amps.

 

[zachtheterrible]

Hi Rolf, I haven't the time to post another picture right now, but it does the same thing no matter how fast or slow the sweep rate is. I'll post another picture later.

 

[Rolf]

Hi Rolf, I haven't the time to post another picture right now, but it does the same thing no matter how fast or slow the sweep rate is. I'll post another picture later.

Have newer seen anything like that before and I serviced and calibrated oscopes for many years at major national weapons manufactures lab.
But like I said, they are IMHO almost impossible to repair without a service manual and an another oscope. And in addition you need a HV probe if you have sweep problems, in order to look for any distortion or ripple in the high voltage and sweep sections. Not until this is done, would I even think about replacing the CRT.
PS. Newer mind the picture, I don't need it now that you explained about the problem being the same at all sweep times.

 

[tunedwolf]

I would have to agree here with Rolf, before scrapping the tube, make certain that both the power supply rails and the H.V stages are clean as the proverbial whistle in terms of operation.