Hameg HM 205-3 Ocilloscope disorted screen.

[Isad]

So i got a oscilloscope from ebay and
ok the seller told me it was bad and the picture sad so
but i am trying to reapir this thing and anyone know
what it could have.
Pls if anyone had this problem and they repaired this
pls leave a commen on what it could have .

Thanks.

[tautech]

You need this PDF:
http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

Do you have a Service manual?
Maybe you can find one from the links in this thread:
https://www.eevblog.com/forum/repair/repair-documents-and-links-sticky-me-please-mods/msg477909/#msg477909

First check the PSU is exactly to manual specs.

[David Hess]

Is there any evidence that the oscilloscope was dropped?  Are there loose pieces rattling around inside the CRT?

That kind of display is what I would expect if the internal CRT elements were damaged and it looks like the screen phosphor has been scraped off from the inside by loose debris.  The curved display of straight lines can be caused by dents in the scan expansion mesh.

[mij59]

Is the picture on the oscilloscope static, or does it wobble a bit ?
Please post some photo's of the boards.
 

[fww]

There are two possibilities:
1. The chassis is magnetic and need demagnetization.
2. Due to the use of time is too long, the CRT has been aging.

[tautech]

There are two possibilities:
1. The chassis is magnetic and need demagnetization.
2. Due to the use of time is too long, the CRT has been aging.

Wrong & wrong.
There may be more than one problem.
PSU voltages and/or ripple LV & HV.

[fww]

@Isad,  could you provide more phenomenas for analysis.
To convert to" x-y", try to move the bright spot up and down and left and right, whether it can be moved out the screen? The bright spot's luminance can be completely closed?
You can also open the chassis, view the CRT, whether there are poles touching together?

[kjn4685]

I go with tautech

[N2IXK]

Have to go with David Hess here. This looks like a case of severe misalignment of internal CRT elements, likely as a result of the scope being dropped.

Do the horizontal and vertical position controls move the display purely vertically or horizontally? If not, you likely need a new CRT (or a new scope at this point).