Hi,

I'm looking to buy my first scope. I don't have a lot of money, so I thought it might be fun to pickup an old one and fix it up. This one looks potentially good:

https://ebay.us/m/XxkBxX

What do you think? The cosmetic condition is very good, which is a good sign. The fact that the CRT comes on is another good sign. I believe the "Beam Find" shown in the video, should show a stable dot in the middle of the screen? What's happening is the beam is dancing about the place in discrete jumps. I asked AI about this and it said:

- Horizontal sweep circuit issue
- Trigger circuit issue
- PSU ripple

All of these seem to be fixable. What do you guys think, is it worth a punt? Is this scope a good one?

Cheers
David

 

Hello,

Keep in mind that very high voltages are used in a crt scope.
Download the service manual and see if the fault is described.
https://www.tek.com/en/oscilloscope/manual/2235-service-manual

Bertus

 

At that price it is worth a try. You might get it working with help from members here on AAC. You might have to borrow a working oscilloscope to find the problem.

 

Hi,

I'm looking to buy my first scope. I don't have a lot of money, so I thought it might be fun to pickup an old one and fix it up. This one looks potentially good:

https://ebay.us/m/XxkBxX

What do you think? The cosmetic condition is very good, which is a good sign. The fact that the CRT comes on is another good sign. I believe the "Beam Find" shown in the video, should show a stable dot in the middle of the screen? What's happening is the beam is dancing about the place in discrete jumps. I asked AI about this and it said:

- Horizontal sweep circuit issue
- Trigger circuit issue
- PSU ripple

All of these seem to be fixable. What do you guys think, is it worth a punt? Is this scope a good one?

Cheers
David

I have two 2465s and one 2445, all in need of repair. Maybe I'll join you on your quest. Post your progress here.

 

I have two 2465s and one 2445, all in need of repair. Maybe I'll join you on your quest. Post your progress here.

Tek 2445 and 2465 are different beasts from 2225 and 2235 series.
Maybe you should start new threads.

 

Thank you for the replies - I'll watch the price on this one and see if it goes much higher. If it's not too pricey then I might bid for it and go for it. I probably do know someone around here with a scope if I needed to borrow one or take it to that person for analysis.

Would be nice to have a scope and get this one working.

Thank you for safety advice @bertus and the link to the service manual. I am aware of the safety issues working with CRTs and valves. The manual has all the schematics and some troubleshooting information. Could be an interesting detective novel to figure out what's wrong and fix it.

 

Tek 2445 and 2465 are different beasts from 2225 and 2235 series.
Maybe you should start new threads.

Yup, you're right. Huge difference between the series. I didn't realize this till I looked it up.

Sorry for the noise.

 

If the power supply has a lot of ripple from bad filter capacitors, that could affect the other problems, and make a simple fix.

 

If the power supply has a lot of ripple from bad filter capacitors, that could affect the other problems, and make a simple fix.

Thank you, there's a good flowchart on p.70 of the manual which advises on various tests. It looks like it might be a simple calibration issue in the best possible case. AI's estimate of the value is that if the price goes above around £80 it's not worth the effort, so I'll keep an eye on the price and see what happens. Would be an interesting project anyway to fix, but I don't want to end up with a lemon. Not having any experience of scopes I'm reliant on your opinions as to whether this project would be worth the effort. I'm not looking to make a profit - I just want a good scope to use for other projects. I could get a cheap USB scope for not much but that's a different path...

 

I did not know that it was an auction. At £27 it was worth buying. Now showing £53. I would pass.

 

For general use, I would get a digital 'scope, since it can perform a lot more measurement functions, including single-shot capture, which is useful in many types of electronic tests.
Also have color screens, which allows easy trace identification for more than one input signal.

 

For general use, I would get a digital 'scope, since it can perform a lot more measurement functions, including single-shot capture, which is useful in many types of electronic tests.
Also have color screens, which allows easy trace identification for more than one input signal.

Yeah, I'm looking at those options. For a comparable digital one offering 2 channels at 100 MHz from a decent brand there is this option at around £230:

https://amzn.eu/d/0iGQb2EJ

Much more function rich, as you say. One disadvantage is that if (when?) it fails, it's way less repairable than the older scopes, but it's a choice to make.

There are boat loads of cheaper USB scopes out there - one wonders if they are actually any good.

 

I did not know that it was an auction. At £27 it was worth buying. Now showing £53. I would pass.

Yes, and it's 6 days out to the close, so it will probably go for a lot higher than this. There's probably some guys out there who could fix this in a second and it's a valuable bit of classic kit in the right hands. For me I'm just looking for a starter scope for use on general projects.

 

One disadvantage is that if (when?) it fails, it's way less repairable than the older scopes,

That's, of course, true of any modern electronic device as compared to older versions.

There are boat loads of cheaper USB scopes out there - one wonders if they are actually any good.

They likely work OK, but you need to carefully look at their specs, and they are certainly not as convenient to use as a dedicated 'scope with its own display and control knobs.
They also may not have as many measurement functions.