Hi,

I'm relatively new to electronics...
I've got a tek 465b that has been working fine for about 8 months.
The other day without any sort of warning the crt failed to come on
when I started it. It still triggers, but I see nothing even when I
press the beam find button. I also happen to have another 465b from a
sour ebay transaction which has no horiz scan.

Is it beyond the capability of someone like myself to swap the crt
following some careful instructions? I know there are high voltages
involved.

Is it worth it to have a professional do this or should I just forget
about the old scope and consider buying something new? I'm starting
to realize that ebay may not be the best place for scopes...

Any opinions?

Thanks,
aaron

(Aaron Kentucky) writes:

Hi,

I'm relatively new to electronics...
I've got a tek 465b that has been working fine for about 8 months.
The other day without any sort of warning the crt failed to come on
when I started it. It still triggers, but I see nothing even when I
press the beam find button. I also happen to have another 465b from a
sour ebay transaction which has no horiz scan.

Is it beyond the capability of someone like myself to swap the crt
following some careful instructions? I know there are high voltages
involved.

Is it worth it to have a professional do this or should I just forget
about the old scope and consider buying something new? I'm starting
to realize that ebay may not be the best place for scopes...

It's probably not a bad CRT but an electronic problem like the HV power
supply..

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
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Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.

In article ,
says...
It's probably not a bad CRT but an electronic problem like the HV power
supply..

Do you have the service manual? I think I've seen it on eBay for about
ten bucks. There is a pretty detailed troubleshooting flowchart for "no
visible display".

--
Jay Levitt |
Wellesley, MA | Hi!
Faster: jay at jay dot eff-em | Where are we going?
http://www.jay.fm | Why am I in this handbasket?

(Aaron Kentucky) wrote in
om:

Hi,

I'm relatively new to electronics...
I've got a tek 465b that has been working fine for about 8 months.
The other day without any sort of warning the crt failed to come on
when I started it.

Did you hear the hiss/crackle of the HV charging the CRT? If not,the HV may
have failed.

It still triggers, but I see nothing even when I
press the beam find button. I also happen to have another 465b from a
sour ebay transaction which has no horiz scan.

Is it beyond the capability of someone like myself to swap the crt
following some careful instructions? I know there are high voltages
involved.

Before you swap CRTs you need to check PS voltages,check for sweep at the
CRT neck pins,check for any vertical offset,check for Z-axis unblanking
signals(you need another scope for some of these checks.)

Is it worth it to have a professional do this or should I just forget
about the old scope and consider buying something new? I'm starting
to realize that ebay may not be the best place for scopes...

Any opinions?

Thanks,
aaron

Swapping the CRT's would require a recalibration of the scope,as CRTs do
not all have the same exact deflection sensitivities.And the CRT anode
voltage has a nasty bite.The CRT acts like a storage capacitor(Leyden
Jar),and had to be discharged before removing it from the scope.

--
Jim Yanik
jyanik-at-kua.net

Hi:

Sorry to hear of your scope trouble ...

1. I got burned 2 for 2 on Ebay scopes

2. I have a Tek 465B and the service manual (I fixed them for a used scope
dealer a few years ago).

I will gladly assist you (walk you through the major tests, or compare readings
from my scope, etc,.

No, the CRT is very simple to swap.

If you are close to PA/OH I also repair scopes, etc., for a very reasonable
fee.

RJ

Jim Yanik wrote in message

Did you hear the hiss/crackle of the HV charging the CRT? If not,the HV may
have failed.

Yes. I also managed to find the manual and am running through the
troubleshooting flowchart now. When I flip it around to slide the
cover off I hear a nice 'jingle jingle.' I'm sure that is not good.

Thanks,
aaron

Thanks for the responses!

Here is some more info after doing some tests. All the low-voltages
check out (I don't have a hv meter.) When I disconnect the power
jumper to the vertical output amp the trace shows with horizontal
scan. This rules out a faulty crt.

Since I have an identical board I swapped it out with the other and
the same thing happens. Furthermore, I discovered that when the top
connector to the vertical deflection plates is disconnected the trace
also shows. This connector is sitting at +54 while the other is at
+16 which seesm to be in violation, but again this happens on both
boards. The delay line into the board is at +225mv and -204mv.

Thanks,
aaron

(Aaron Kentucky) wrote in message . com...
Thanks for the responses!

Here is some more info after doing some tests. All the low-voltages
check out (I don't have a hv meter.) When I disconnect the power
jumper to the vertical output amp the trace shows with horizontal
scan. This rules out a faulty crt.

no, it doesn't rule out a defective CRT: It'S still possible you have
a problem with the vert. plates because of the "jingle" you mentioned.
May be something internal is broken.
Just a "could be" , no "must".



Since I have an identical board I swapped it out with the other and
the same thing happens. Furthermore, I discovered that when the top
connector to the vertical deflection plates is disconnected the trace
also shows. This connector is sitting at +54 while the other is at
+16 which seesm to be in violation, but again this happens on both
boards. The delay line into the board is at +225mv and -204mv.

Thanks,
aaron

Looks like you have a problem in the preamp section and or
interconection.

i'd recommend you get a SERVICE Manual for this scope.
That's fairly easy: Just google for "bama" , there is a 465b excellent
scan for download in bama.sbc.edu in the Tektronix section(well, don't
nail me for the exact URL, just a result " of brain scanned")

hth,
Andreas

"Aaron Kentucky" wrote in message
Yes. I also managed to find the manual and am running through the
troubleshooting flowchart now. When I flip it around to slide the
cover off I hear a nice 'jingle jingle.' I'm sure that is not good.

Thanks,
aaron


Yuck, a jingle-jingle often means that a little bit of glass has broken off
one of the internal CRT supports. Those glass support rods are under a bit
of strain, and it doesnt take much to crack a piece off of them. I've seen
this happen a time or two.

What happens then is if you tilt the scope the bits of glass eventually put
a hole or dent in this fragile little metal screen that acts like a
magnifying lens-- then the scope trace goes all fireworksy and the CRT is
useless. Really, really cool to play with, better than a lava lamp, but
mostly useless as a scope.

(TekMan) wrote in
m:

(Aaron Kentucky) wrote in message
. com...
Thanks for the responses!

Here is some more info after doing some tests. All the low-voltages
check out (I don't have a hv meter.) When I disconnect the power
jumper to the vertical output amp the trace shows with horizontal
scan. This rules out a faulty crt.

no, it doesn't rule out a defective CRT: It'S still possible you have
a problem with the vert. plates because of the "jingle" you mentioned.
May be something internal is broken.
Just a "could be" , no "must".

If he has a H sweep roughly centered in the graticule,then the CRT is
probably good.Munge up the deflection plates,and he would not have a on-
screen trace,and there'd be glass fragments stuck to the phosphor causing
bright or dark spots.If the mesh lens gets distorted,then you can get all
sorts of squiggly traces.




Since I have an identical board I swapped it out with the other and
the same thing happens. Furthermore, I discovered that when the top
connector to the vertical deflection plates is disconnected the trace
also shows. This connector is sitting at +54 while the other is at
+16 which seesm to be in violation, but again this happens on both
boards. The delay line into the board is at +225mv and -204mv.

Thanks,
aaron

Looks like you have a problem in the preamp section and or
interconection.

He could short the delay line pins on the preamp PCB,and if the trace
centers,then it's the preamp,if not,the vert output amp.He could short the
CRT vertical pins and see if the trace centers,if so,the CRT is OK,and bad
V-output amp.That IC may be hard to find.

--
Jim Yanik
jyanik-at-kua.net

I don't know if anyone is interested or not but i figure this will
still be good for the archives if someone else has the problem in the
future.

It turned out to be the vertical output amp after all. I tried
swapping them again and this time it worked perfectly! I must have
made a mistake the first time. Anyway, thank you all who responded to
help me out as I'm extremely happy that I got this thing going again
(and got use out of the broken 465b that was collecting dust!!)

On top of all that I learned a great deal about the workings of my
scope.

Thanks!
aaron