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Good day. I'm having some trouble with my beloved Tektronix 465B and I'm hoping some gurus on this list may be able to assist me. Let me first say that I am a fledgling electronics hobbyist and have little or no experience troubleshooting something as complex as this scope. I purchased the Tek 465B around 2012. When I purchased the scope, all was well. Now, a few years later and the scope is acting up. I had the scope in a closet for about a year. My first boy was born and I didn't have time to play with it. In any case, I just pulled out the scope this week and hooked it up to a signal generator as a test. The scope trace only fills part of the screen.Here is a link to a short youtube video I posted that shows the problem.




I contacted a friend who is a Tek expert who said the problem may be that half of the differential drive has failed. As I am completely new to this electronics game, I don't feel comfortable breaking into the scope and probing around. Maybe I will in a few years after I get more building and troubleshooting experience under my belt. So I thought I would reach out to this group to see if anyone here has had a similar experience and can guide me along the way, or if there are any businesses/hobbyists that I can send the scope for possible repair.


Thank you for any assistance. I look forward to hearing back.


Kevin

Hey Kevin,

Welcome to the group. Start by grabbing the sevice manual, which can be found online. Here < > is one place. Give it a read, take a deep breath, then dive in to diagnosis and repair. These old service manuals are amazing.
Now, I don't have a scope from this era myself, but I understand the transistors may be socketed. This may help as it's easy to pull them out for testing, and to swap them around.
Do you have access to a second scope for troubleshooting?


Siggi

I just took a quick peek at the horizontal deflection circuit schematics. Doesn't look too frightening, first step would be to check the DC supplies. A common failure is failing or drooping supplies. Horizontal seems to use 110V, 55V, 5V and -8V. Measure the DC level, and if you have a decent DMM, measure AC for signs of ripple too. If those check out, it's to the DC levels in the schematic to see where those are at.
You'll probably be closer to a cause with that already.


Good luck,
Siggi

One more thing. It appears Artek Manuals have three different 465 scans for different serial ranges < >. You may want to buy the one that matches your scope's serial number (on the front of the scope, I believe). Dave's scans are going to be better quality than the free one on bama, and OCR-ed too.

Feel free to shoot questions and observations as you go, someone may notice trouble you miss in the heat of the moment. In addition to tinkerers like me, there are real-life experts hanging out here, but they seem to reserve themselves for the tougher problems :).


Have fun,
Siggi

Siggi’s right… get the proper manual….artek’s are very good….
read the manual…. Tek has been very very good about teaching you HOW it works and then letting you trouble shoot it. The 465b is a very good scope to work on. take the feet off of the back and the two center screws and then carefully slide the whole cover off. LOOK!….. study the manual and see where things are and where the dangers are and where to make your test measurements. most of the 465 has individual transistors making things a lot easier to test. from the look of your video 1/2 of the horizontal amp is not working. first just for fun…wiggle any of the transistors on the horz bd that are in sockets…. you could get lucky…. then as Siggi suggested, check your power supply voltages. go slow and read as you go..you’ll get done…there is plenty of help here…


jim

On Dec 2, 2014, at 6:44 PM, siggi@... [TekScopes] <TekScopes@...> wrote:

One more thing. It appears Artek Manuals have three different 465 scans for different serial ranges < <>>. You may want to buy the one that matches your scope's serial number (on the front of the scope, I believe). Dave's scans are going to be better quality than the free one on bama, and OCR-ed too.

Feel free to shoot questions and observations as you go, someone may notice trouble you miss in the heat of the moment. In addition to tinkerers like me, there are real-life experts hanging out here, but they seem to reserve themselves for the tougher problems :).


Have fun,
Siggi

[Non-text portions of this message have been removed]

On 12/02/2014 10:10 PM, Jim Popwell jpopwell@... [TekScopes] wrote:

Siggi’s right… get the proper manual….artek’s are very good….
read the manual…. Tek has been very very good about teaching you HOW it works and then letting you trouble shoot it. The 465b is a very good scope to work on. take the feet off of the back and the two center screws and then carefully slide the whole cover off. LOOK!….. study the manual and see where things are and where the dangers are and where to make your test measurements. most of the 465 has individual transistors making things a lot easier to test. from the look of your video 1/2 of the horizontal amp is not working. first just for fun…wiggle any of the transistors on the horz bd that are in sockets…. you could get lucky…. then as Siggi suggested, check your power supply voltages. go slow and read as you go..you’ll get done…there is plenty of help here…


jim

Yeah, and it's been a while since we've had a good troubleshooting thread. I learn from all of them!

Mark

Hi Kevin

Before you do anything, check your power supply voltages for correct voltages AND ripple. I have repaired hundreds of 4xx scopes, some with your problems, and almost all of them had severe ripple on one of the supplies. If your scope has been stored for a while, that's by far, the most likely problem.

Keep us posted and good luck. Tad WA1FQO

Thanks to everyone who has emailed the list with suggestions for me to try
to cure my ailing scope. I have a copy of the service manual and have taken
a look at the various schematics. To say I'm intimated is an
understatement. Just looking at the voltages coming out of this unit scares
me. I am just starting out on this electronics hobby path, and spend my
time playing with low voltage DC circuits. To be honest, I'm not even sure
how to go about checking the voltage within the unit, and forget about
techniques to determine ripple on the supply. I have trouble really
understanding what is going on in a typical RC circuit, and that's just
running off a nine-volt battery. I'm afraid this one is over my head. It's
a shame as I really like the scope, and I'm finally in a position with my
family life that I can start fiddling with it. The scope had been in
storage for about a year as I focused on my family and work.

Again, thanks to everyone who gave some practical suggestions. I will file
them away. And if I can't find someone who has experience with these scopes
and who can take a look at it, then, one day, when I feel more confident
playing with high-voltage equipment, I might drag it out and see about
repairing it.

OK, back to my lurking status.

Kevin

On 12/3/2014 9:17 AM, Kevin Crossett kcrossett@... [TekScopes] wrote:

Thanks to everyone who has emailed the list with suggestions for me to try
to cure my ailing scope. I have a copy of the service manual and have
taken
a look at the various schematics. To say I'm intimated is an
understatement. Just looking at the voltages coming out of this unit
scares
me. I am just starting out on this electronics hobby path, and spend my
time playing with low voltage DC circuits. To be honest, I'm not even sure
how to go about checking the voltage within the unit

This is a very easy thing to do:
With the cover off and the the scope upside down the voltage test points
are easy to fine and
plainly marked.
Even one of those ( free or $5 ) Harbor freight digital meters can show
you if you have a major
problem in the power supplies.
Have you done the beam finder and X/Y operation tests?

, and forget about
techniques to determine ripple on the supply. I have trouble really
understanding what is going on in a typical RC circuit, and that's just
running off a nine-volt battery. I'm afraid this one is over my head. It's
a shame as I really like the scope, and I'm finally in a position with my
family life that I can start fiddling with it. The scope had been in
storage for about a year as I focused on my family and work.

Again, thanks to everyone who gave some practical suggestions. I will file
them away. And if I can't find someone who has experience with these
scopes
and who can take a look at it, then, one day, when I feel more confident
playing with high-voltage equipment, I might drag it out and see about
repairing it.

OK, back to my lurking status.

Kevin

Where are you located? Maybe someone on the list lives near you and can help you learn this stuff.

Regards

Hi Bert. I do plan to open the scope up and take a look. At the very least
I think I can giggle some of the transistors in their sockets, and it
sounds like I will be able to take general voltage measurements using my
DMM. The high voltage stuff scares me a lot, and I don't want my wife and
son to find me on the garage floor after a careless measurement, hi hi. I
will report back any of my findings.



On Wed, Dec 3, 2014 at 11:08 AM, Bert Haskins bhaskins@...
[TekScopes] <TekScopes@...> wrote:

On 12/3/2014 9:17 AM, Kevin Crossett kcrossett@... [TekScopes]
wrote:

Thanks to everyone who has emailed the list with suggestions for me to

try

to cure my ailing scope. I have a copy of the service manual and have
taken
a look at the various schematics. To say I'm intimated is an
understatement. Just looking at the voltages coming out of this unit
scares
me. I am just starting out on this electronics hobby path, and spend my
time playing with low voltage DC circuits. To be honest, I'm not even

sure

how to go about checking the voltage within the unit

This is a very easy thing to do:
With the cover off and the the scope upside down the voltage test points
are easy to fine and
plainly marked.
Even one of those ( free or $5 ) Harbor freight digital meters can show
you if you have a major
problem in the power supplies.
Have you done the beam finder and X/Y operation tests?

, and forget about
techniques to determine ripple on the supply. I have trouble really
understanding what is going on in a typical RC circuit, and that's just
running off a nine-volt battery. I'm afraid this one is over my head.

It's

a shame as I really like the scope, and I'm finally in a position with my
family life that I can start fiddling with it. The scope had been in
storage for about a year as I focused on my family and work.

Again, thanks to everyone who gave some practical suggestions. I will

file

them away. And if I can't find someone who has experience with these
scopes
and who can take a look at it, then, one day, when I feel more confident
playing with high-voltage equipment, I might drag it out and see about
repairing it.

OK, back to my lurking status.

Kevin

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Yahoo Groups Links

Hi Kevin,
where are you… if your in the Oregon area, I could help.
jim

Hi Tom. I live in Hampton Roads, Virginia. Not sure if there are any Tek
gurus in this region of the country, but would appreciate a mentor. This
high voltage stuff is scary business for someone with no formal training.

Where are you located? Maybe someone on the list lives near you and can
help you learn this stuff.

Regards

Hi Jim. Thanks for the kind offer, and I wish we lived closer to each
other. I live in the Hampton Roads area of Virginia, York County to be
exact.

It happens that diagram <10> of the Horizontal Amplifier is missing from the .djvu file at BAMA. I have never downloaded the .pdf file so I don't know about that one. Anyway, diagram <10> is one of the diagrams shown in 465bMissingPages.pdf .

Albert

Thanks Albert. I have the service manual and have begun studying diagram
<10>. Not quite sure what I am looking at thus far. Perhaps when I can
really study it I will start to see the light.

Hey Kevin,

I expect once you get into it, you'll find this isn't nearly as frightening as you now think it is. The satisfaction in effecting a repair is huge - not to mention the bragging rights!


The main power supply in the 465b is an old-style power transformer with multiple secondaries for the various supplies. This means there's no switch-mode hanky-panky there to tangle with - just old style bridge rectification and filtering.
Once you have the cover off, you'll see where the CRT's high-voltage (HV) supply is generated and how it's covered and protected. Stay away from the HV. This is not hard - there are cautionary signs and text on the covers you're not to remove, and the wiring will be bright red and quite well insulated.
You'll also want to stay away from the mains input and the transformer's primary, at least until you get a little more comfortable.


The only thing to really worry from there are the 110 and 55V supplies, you won't even feel the others if you were to touch them.
The 110/55V supplies *will* sting if you touch them, but they're not likely to kill or seriously maim you. There's IMHO more injury risk in falling or banging yourself up when you jerk away from the sting, than from the sting itself :).


In any case, when you probe this, start by securing your negative probe to a grounding point. Any metallic point of the scope's chassis will do for basic supply voltage measurements. You can do this e.g. with crocodile clip leads or the like.
Then turn the scope on, and probe around with the positive probe, keeping the other hand in your pocket or behind your back. This vastly reduces the chance of shock, as well as the risk of injury in case of shock.


If you're still worried, you can reduce the risk of shock still more by wearing any form of insulating shoewear - which means practically any shoes you own. The scope's power supplies are referenced to mains earth, and if your body has no connetivity to mains earth, then you can't get a shock even by touching one point of your body to the supplies (this is still not recommended practice :).



Siggi

Like was said before, measure all the power supply test points. Measure them with a DMM and then measure them again with another scope set to ac coupling. This will allow you to look at any ripple on the supply. I have fixed a lot of test equipment with this method. It is so simple to do and will tell you immediately if you have a power supply problem.

I bought a very expensive frequency counter on ebay for 25 bucks. It was sold as for parts or repair. They actually took a picture of thing turned on showing a frequency readout of 120 hz with nothing hooked to the input. I guessed it was measuring the frequency of a bad power supply rail. I was right. I still have this fantastic counter after replacing a simply filter capacitor. One of my best buys on ebay.


Michael

Thanks Siggi. Your instructions are inspiring. I will get the scope in the
garage tonight, pull off the cover and see what's going on. I'll report
back any findings.

Cheers
Kevin

Thanks for the insights Michael. I will check the voltages. I don't have a
second scope available to me, so I may have to figure out another way to
check for ripple. I think your score on ebay is fantastic, and shows what a
little troubleshooting can do to fill a lab with test equipment.