Hi,

I recently bought an oscilloscope on eBay, and I don't know if the
seller lied in the description or if it was damaged during the
transport, but the trace is completely distorted and shows strange
grid-like patterns. I made a few pictures and a little video :

http://img222.imageshack.us/img222/1984/focused.jpg
http://img212.imageshack.us/img212/6566/unfocused.jpg
http://www.youtube.com/watch?v=c5RTaTM0tJk

The shape of the trace changes when I change the y-position dial. This
makes me think the problem is in the tube and not in the electronics.

I'm wondering if this could be caused by a bent grid somewhere in the
tube ? Could it have been damaged if the oscilloscope received a shock
for example ?

I think the tube is pretty much toast, as well as the scope since there
is no way I could find a replacement tube (Tektronix 2225), but I
wouldn't mind to be proven wrong :-) Thanks.

On May 8, 1:18 pm, vic wrote:
Hi,

I recently bought an oscilloscope on eBay, and I don't know if the
seller lied in the description or if it was damaged during the
transport, but the trace is completely distorted and shows strange
grid-like patterns. I made a few pictures and a little video :

http://img222.imageshack.us/img222/1...?v=c5RTaTM0tJk

The shape of the trace changes when I change the y-position dial. This
makes me think the problem is in the tube and not in the electronics.

I'm wondering if this could be caused by a bent grid somewhere in the
tube ? Could it have been damaged if the oscilloscope received a shock
for example ?

I think the tube is pretty much toast, as well as the scope since there
is no way I could find a replacement tube (Tektronix 2225), but I
wouldn't mind to be proven wrong :-) Thanks.

Hi
Check bypass electrolytics. It looks like the axis are cross talking
through the supply lines.
Dwight

"vic" wrote in message
...
Hi,

I recently bought an oscilloscope on eBay, and I don't know if the seller
lied in the description or if it was damaged during the transport, but the
trace is completely distorted and shows strange grid-like patterns. I made
a few pictures and a little video :

http://img222.imageshack.us/img222/1984/focused.jpg
http://img212.imageshack.us/img212/6566/unfocused.jpg
http://www.youtube.com/watch?v=c5RTaTM0tJk

The shape of the trace changes when I change the y-position dial. This
makes me think the problem is in the tube and not in the electronics.

I'm wondering if this could be caused by a bent grid somewhere in the tube
? Could it have been damaged if the oscilloscope received a shock for
example ?

I think the tube is pretty much toast, as well as the scope since there is
no way I could find a replacement tube (Tektronix 2225), but I wouldn't
mind to be proven wrong :-) Thanks.

I strongly suspect power supply problems. Check for bad power supply filter
capacitors. These are typical causes of distorted and fuzzy traces on a
scope.
As I remember, this model scope isn't particularly easy to disassemble and
repair, so get ready for some bench time. If you have or can borrow another
scope, that will make your troubleshooting a LOT easier. If you don't have
a service manual, you really should get one. You can buy a digital copy
from http://artekmed.startlogic.com/page2.html for $10.00. Artek sells high
quality scanned copies; I can recommend them from personal experience.
Cheers!

--
HAM AND EGGS -- A day's work for a chicken, a lifetime commitment for a pig.

Dave M

Dave M wrote:
"vic" wrote in message
...
Hi,

I recently bought an oscilloscope on eBay, and I don't know if the seller
lied in the description or if it was damaged during the transport, but the
trace is completely distorted and shows strange grid-like patterns. I made
a few pictures and a little video :

http://img222.imageshack.us/img222/1984/focused.jpg
http://img212.imageshack.us/img212/6566/unfocused.jpg
http://www.youtube.com/watch?v=c5RTaTM0tJk

The shape of the trace changes when I change the y-position dial. This
makes me think the problem is in the tube and not in the electronics.

I'm wondering if this could be caused by a bent grid somewhere in the tube
? Could it have been damaged if the oscilloscope received a shock for
example ?

I think the tube is pretty much toast, as well as the scope since there is
no way I could find a replacement tube (Tektronix 2225), but I wouldn't
mind to be proven wrong :-) Thanks.

I strongly suspect power supply problems. Check for bad power supply filter
capacitors. These are typical causes of distorted and fuzzy traces on a
scope.
As I remember, this model scope isn't particularly easy to disassemble and
repair, so get ready for some bench time. If you have or can borrow another
scope, that will make your troubleshooting a LOT easier. If you don't have
a service manual, you really should get one. You can buy a digital copy
from http://artekmed.startlogic.com/page2.html for $10.00. Artek sells high
quality scanned copies; I can recommend them from personal experience.
Cheers!

Tubes busted internally, if it was signal distortion the shape would be
the same top, bottom or middle of the screen.

You will most likely here glass tinkling inside the tube if you tip the
scope, also remove the blue implosion filter and check for tiny marks on
the phosphor from debris.
JC

On May 8, 4:08*pm, "Dave M" wrote:
"vic" wrote in message

...





Hi,

I recently bought an oscilloscope on eBay, and I don't know if the seller
lied in the description or if it was damaged during the transport, but the
trace is completely distorted and shows strange grid-like patterns. I made
a few pictures and a little video :

http://img222.imageshack.us/img222/1984/focused.jpg
http://img212.imageshack.us/img212/6566/unfocused.jpg
http://www.youtube.com/watch?v=c5RTaTM0tJk

The shape of the trace changes when I change the y-position dial. This
makes me think the problem is in the tube and not in the electronics.

I'm wondering if this could be caused by a bent grid somewhere in the tube
? Could it have been damaged if the oscilloscope received a shock for
example ?

I think the tube is pretty much toast, as well as the scope since there is
no way I could find a replacement tube (Tektronix 2225), but I wouldn't
mind to be proven wrong :-) Thanks.

I strongly suspect power supply problems. *Check for bad power supply filter
capacitors. *These are typical causes of distorted and fuzzy traces on a
scope.
As I remember, this model scope isn't particularly easy to disassemble and
repair, so get ready for some bench time. *If you have or can borrow another
scope, that will make your troubleshooting a LOT easier. *If you don't have
a service manual, you really should get one. *You can buy a digital copy
fromhttp://artekmed.startlogic.com/page2.htmlfor $10.00. *Artek sells high
quality scanned copies; I can recommend them from personal experience.
Cheers!

--
HAM AND EGGS -- A day's work for a chicken, a lifetime commitment for a pig.

Dave M- Hide quoted text -

- Show quoted text -

You must get another scope and see if there are signals getting to the
CRT deflection plates when the input is grounded. Bad electrolytics
are the most likely problem!!! But, a scope is the only way to tell
for sure.

vic wrote:
Hi,

I recently bought an oscilloscope on eBay, and I don't know if the
seller lied in the description or if it was damaged during the
transport, but the trace is completely distorted and shows strange
grid-like patterns. I made a few pictures and a little video :

http://img222.imageshack.us/img222/1984/focused.jpg
http://img212.imageshack.us/img212/6566/unfocused.jpg
http://www.youtube.com/watch?v=c5RTaTM0tJk

The shape of the trace changes when I change the y-position dial. This
makes me think the problem is in the tube and not in the electronics.

I'm wondering if this could be caused by a bent grid somewhere in the
tube ? Could it have been damaged if the oscilloscope received a shock
for example ?

I think the tube is pretty much toast, as well as the scope since there
is no way I could find a replacement tube (Tektronix 2225), but I
wouldn't mind to be proven wrong :-) Thanks.

Tubes busted internally, if it was signal distortion the shape would be
the same top, bottom or middle of the screen.

You will most likely here glass tinkling inside the tube if you tip the
scope, also remove the blue implosion filter and check for tiny marks on
the phosphor from debris.
JC

In fact unless your filter is dirty, I can see pock marks on the
phosphor behind the filter, there should not be any marks at all.

JC

Archon wrote:
Tubes busted internally, if it was signal distortion the shape would be
the same top, bottom or middle of the screen.

You will most likely here glass tinkling inside the tube if you tip the
scope, also remove the blue implosion filter and check for tiny marks on
the phosphor from debris.

Yes you're spot on, I disassembled the tube to check if any damage was
visible, and there were little pieces of glass going around inside. One
of the glass posts holding the deflectors and electron gun was broken.
There are indeed several marks on the phosphor, as if it was scratched
from the inside.

Out of curiosity, do you know what element in particular causes the
strange distorsion ? Since the shape changes whith the y-position, I
figure this would have to be after the vertical deflection plates, but I
don't see what it could be.

v.

hr(bob) wrote:
You must get another scope and see if there are signals getting to the
CRT deflection plates when the input is grounded. Bad electrolytics
are the most likely problem!!! But, a scope is the only way to tell
for sure.

In this case shouldn't the distorsion be the same whatever the
y-position is ?

I have another scope (which I hoped to slightly upgrade), so I'll do as
you suggest and check the signal on the vertical deflection plates, to
be sure.

v.

vic wrote in
:

Hi,

I recently bought an oscilloscope on eBay, and I don't know if the
seller lied in the description or if it was damaged during the
transport, but the trace is completely distorted and shows strange
grid-like patterns. I made a few pictures and a little video :

http://img222.imageshack.us/img222/1984/focused.jpg
http://img212.imageshack.us/img212/6566/unfocused.jpg
http://www.youtube.com/watch?v=c5RTaTM0tJk

The shape of the trace changes when I change the y-position dial. This
makes me think the problem is in the tube and not in the electronics.

I'm wondering if this could be caused by a bent grid somewhere in the
tube ? Could it have been damaged if the oscilloscope received a shock
for example ?

Oh,yes,seen lots of them.
I worked for TEK 21.5 yrs,Indy and Orlando service centers.

I think the tube is pretty much toast, as well as the scope since there
is no way I could find a replacement tube (Tektronix 2225),

don't be so sure;Ebay or Sphere in Canada may have parts.

but I
wouldn't mind to be proven wrong :-) Thanks.

IMO,the CRT is toast;judging from the bent trace and glow on the left side
of the graticule.But you should check the power supplies anyways.
That's always step ONE.

FYI,checking tube geometry is best done with a signal displayed.
Then you can see the vertical distortions.

If you do remove the CRT,tilt it and see if you hear little bits tinkling
inside,that's from the electron gun glass rods that got cracked.Sometimes
you can see them on the faceplate,or they make spots on the graticule.

--
Jim Yanik
jyanik
at
kua.net

vic wrote in
:

Archon wrote:
Tubes busted internally, if it was signal distortion the shape would
be the same top, bottom or middle of the screen.

You will most likely here glass tinkling inside the tube if you tip
the scope, also remove the blue implosion filter and check for tiny
marks on the phosphor from debris.

Yes you're spot on, I disassembled the tube to check if any damage was
visible, and there were little pieces of glass going around inside.
One of the glass posts holding the deflectors and electron gun was
broken. There are indeed several marks on the phosphor, as if it was
scratched from the inside.

Out of curiosity, do you know what element in particular causes the
strange distorsion ? Since the shape changes whith the y-position, I
figure this would have to be after the vertical deflection plates, but
I don't see what it could be.

v.


It could be the final mesh screen,and/or any one of the defelection plates.

--
Jim Yanik
jyanik
at
kua.net

Dave M wrote:

You can buy a digital copy
from http://artekmed.startlogic.com/page2.html for $10.00. Artek sells high
quality scanned copies; I can recommend them from personal experience.
Cheers!

They do neither offer a phone number nor their location. And their
Web-Site seems to be broken (with Firefox 2).
http://artekmed.startlogic.com/page6.html

Regards,
H.

Heinz Schmitz wrote:
Dave M wrote:

You can buy a digital copy
from http://artekmed.startlogic.com/page2.html for $10.00. Artek sells high
quality scanned copies; I can recommend them from personal experience.
Cheers!

They do neither offer a phone number nor their location. And their
Web-Site seems to be broken (with Firefox 2).
http://artekmed.startlogic.com/page6.html

Regards,
H.



OMFG WTF Here we go again

JC

Dave M wrote:
scope, that will make your troubleshooting a LOT easier. If you don't have
a service manual, you really should get one. You can buy a digital copy
from http://artekmed.startlogic.com/page2.html for $10.00. Artek sells high
quality scanned copies; I can recommend them from personal experience.

I never buy from this kind of shop since their business model seems
dodgy to me. Basically they sell copyrighted works of others, and stuff
that is sometimes freely available elsewhere.

v.

Just to give some feedback, I tested the deflection plate voltages and
power supply and they look correct to me. So I'm a bit ****ed off that
an otherwise working device was destroyed by careless handling on the
part of the sender. I guess my current very old, unreliable and
completely decalibrated oscilloscope will have to do a little longer :-)

v.

vic wrote:

The auction did not show the oscilloscope in operation, however the
description said that it was in working condition. While technically it
does operate, that's not what I consider working condition. I only paid
40 euro though, so I think I won't bother with the procedure, especially
if I have to send it back to the seller, with proper packaging this
time. I'll probably save some more and buy a recent model one day.

This is a very wise decision, imho. I think, that on-line purchase of
fragile goods and delivery by mail always carries a considerable risk
of receiving the article damaged - be it, because the sender broke it
before or while packaging, because he packed it not well enough,
because the delivery service threw it around, because a heavy other
parcel was thrown onto it, or because the buyer dropped it himself
while carrying it to his workbench, or because of something else.

In the end, the problem imho is, to prove to the judge without doubt,
what really did happen.

The solution I prefer is, to buy such goods from sellers located near
to my place, so I can drive over, eventually have it shown to work,
and to bring it home myself. This way, I often meet nice people, too.

Regards,
H.

vic wrote:

Just to give some feedback, I tested the deflection plate voltages and
power supply and they look correct to me. So I'm a bit ****ed off that
an otherwise working device was destroyed by careless handling on the
part of the sender. I guess my current very old, unreliable and
completely decalibrated oscilloscope will have to do a little longer :-)

If you think that everything else of the scope is ok, then why not sit
at the bank of the river and wait for a replacement crt to swim by?

Or even walk into the river and stir up one from the bench of some
replacement guru? In such cases I find we are really blessed with
the internet :-).

Regards,
H.

vic wrote in
:

Dave M wrote:
scope, that will make your troubleshooting a LOT easier. If you
don't have a service manual, you really should get one. You can buy
a digital copy from http://artekmed.startlogic.com/page2.html for
$10.00. Artek sells high quality scanned copies; I can recommend
them from personal experience.

I never buy from this kind of shop since their business model seems
dodgy to me. Basically they sell copyrighted works of others, and
stuff that is sometimes freely available elsewhere.

v.


TEK has released their copyright on obsolete products.
So,the company provides a service,at a price.

--
Jim Yanik
jyanik
at
kua.net

On Fri, 08 May 2009 22:18:43 +0200 vic wrote in
Message id: :

Hi,

I recently bought an oscilloscope on eBay, and I don't know if the
seller lied in the description or if it was damaged during the
transport, but the trace is completely distorted and shows strange
grid-like patterns. I made a few pictures and a little video :

http://img222.imageshack.us/img222/1984/focused.jpg
http://img212.imageshack.us/img212/6566/unfocused.jpg
http://www.youtube.com/watch?v=c5RTaTM0tJk

The shape of the trace changes when I change the y-position dial. This
makes me think the problem is in the tube and not in the electronics.

I'm wondering if this could be caused by a bent grid somewhere in the
tube ? Could it have been damaged if the oscilloscope received a shock
for example ?

I think the tube is pretty much toast, as well as the scope since there
is no way I could find a replacement tube (Tektronix 2225), but I
wouldn't mind to be proven wrong :-) Thanks.

Shoot an email or phone someone at https://www.techrecovery.com/
We have lots o' dead Tek scopes that are not worth repairing. Dunno what
they'd charge for the tube, but $75 + shipping sounds reasonable to me.
Tell them Jay sent you. Just do a bit of homework first and find out what
other models share the same tube (So I don't have to do too much digging)
and have the Tek part #. Make sure you put that info into your query.

On 12 May 2009 12:10:35 GMT Jim Yanik wrote in Message
id: :

vic wrote in
:

Dave M wrote:
scope, that will make your troubleshooting a LOT easier. If you
don't have a service manual, you really should get one. You can buy
a digital copy from http://artekmed.startlogic.com/page2.html for
$10.00. Artek sells high quality scanned copies; I can recommend
them from personal experience.

I never buy from this kind of shop since their business model seems
dodgy to me. Basically they sell copyrighted works of others, and
stuff that is sometimes freely available elsewhere.

v.


TEK has released their copyright on obsolete products.
So,the company provides a service,at a price.

Yep. Additionally, Dave's manuals are of very high quality. Many of them
are text searchable unlike the free online versions. Very useful when the
manual is 600 pages in length.

In article ,
vic wrote:

The shape of the trace changes when I change the y-position dial. This
makes me think the problem is in the tube and not in the electronics.

This makes me think there's dirt in the selector switch. Spray a little
DeoxIT in there and run the switch back and forth several times.

Jim Yanik wrote in
:

vic wrote in
:

Dave M wrote:
scope, that will make your troubleshooting a LOT easier. If you
don't have a service manual, you really should get one. You can buy
a digital copy from http://artekmed.startlogic.com/page2.html for
$10.00. Artek sells high quality scanned copies; I can recommend
them from personal experience.

I never buy from this kind of shop since their business model seems
dodgy to me. Basically they sell copyrighted works of others, and
stuff that is sometimes freely available elsewhere.

v.


TEK has released their copyright on obsolete products.

I should have typed "obsolete product manuals".
sorry.

So,the company provides a service,at a price.




--
Jim Yanik
jyanik
at
kua.net

On Tue, 12 May 2009 02:54:27 +0200, vic wrote:

Just to give some feedback, I tested the deflection plate voltages and
power supply and they look correct to me. So I'm a bit ****ed off that
an otherwise working device was destroyed by careless handling on the
part of the sender. I guess my current very old, unreliable and
completely decalibrated oscilloscope will have to do a little longer :-)

v.

You may have some debris lodged inside the electron gun. Tap on the neck of
the CRT and see if the trace changes. Maybe you can apply some rough handling
of your own.

--
Boris