Tek 2465B died all or a sudden.

[Matthew Hagerty]

Greetings,

I have a very low hours Tek 2465B that just stopped working the other
day when I went to use it. For about the last year the digital
display information on the CRT has been a little flakey, usually
displaying about half an inch from the top and bottom of the CRT
instead of right at the top and bottom. But every now and then the
digital display infomation would jump back to where it is supposed to
be. However, this did not affect any of the traces (they would always
display properly) so I lived with it.

But, when I went to turn it on the other day (after sitting for about
a month of no use) it ran through its start up sequence, then stopped
with the CH1-ADD LED on and would not respond to *any* front panel
buttons. Even the beam-find does nothing.

After powering off and on a few times it finally came up with a more
normal front panel display, i.e. I could push buttons and the LED's
would change and I could hear relays click inside the unit, but still
no display or trace on the CRT. Also, whenever I pushed any of the
buttons *all* the front panel LED's would flicker in unison. When I
power the unit off or on I see a quick flash of a trace on the CRT,
but I have no idea if this means anything.

This scope is by far the nicest piece of equipment I own and only
because I got it at a really good price. Tektronix wants $2k to fix
it (ouch) but I can't even consider something like that being a
hobbiest. Usually I'd dive right in myself and try to fix it, but
after removing the cover I just stood there babbling at the thing.
After looking at all the unlabeled and custom TEK parts, I figured
there was just no way I could begin to fix it...

If anyone has seen this problem before or can offer any insight I'd
greatly appreciate it!

Thanks,
Matthew

 

[Jim Yanik]

[email protected] (Matthew Hagerty) wrote in

Greetings,

I have a very low hours Tek 2465B that just stopped working the other
day when I went to use it. For about the last year the digital
display information on the CRT has been a little flakey, usually
displaying about half an inch from the top and bottom of the CRT
instead of right at the top and bottom. But every now and then the
digital display infomation would jump back to where it is supposed to
be. However, this did not affect any of the traces (they would always
display properly) so I lived with it.

But, when I went to turn it on the other day (after sitting for about
a month of no use) it ran through its start up sequence, then stopped
with the CH1-ADD LED on and would not respond to *any* front panel
buttons. Even the beam-find does nothing.

After powering off and on a few times it finally came up with a more
normal front panel display, i.e. I could push buttons and the LED's
would change and I could hear relays click inside the unit, but still
no display or trace on the CRT. Also, whenever I pushed any of the
buttons *all* the front panel LED's would flicker in unison. When I
power the unit off or on I see a quick flash of a trace on the CRT,
but I have no idea if this means anything.

This scope is by far the nicest piece of equipment I own and only
because I got it at a really good price. Tektronix wants $2k to fix
it (ouch) but I can't even consider something like that being a
hobbiest. Usually I'd dive right in myself and try to fix it, but
after removing the cover I just stood there babbling at the thing.
After looking at all the unlabeled and custom TEK parts, I figured
there was just no way I could begin to fix it...

If anyone has seen this problem before or can offer any insight I'd
greatly appreciate it!

Thanks,
Matthew

Step one is to get a service manual.
Step two is to read the circuit description.(the whole thing)
Step three is to check the LV power suplies.

There are also fault codes in the SVC manual,that tell from what front
panel led being lit,what part of the scope has a problem.

 

[Matthew Hagerty]

[email protected] (Matthew Hagerty) wrote in


Step one is to get a service manual.
Step two is to read the circuit description.(the whole thing)
Step three is to check the LV power suplies.

There are also fault codes in the SVC manual,that tell from what front
panel led being lit,what part of the scope has a problem.

You really think I could fix it? I'm certainly willing to try, it's
just a little intimidating. I will get a service manual, I've been
looking for a source all morning, could you perhaps suggest one?

Thanks,
Matthew

 

[Jim Yanik]

[email protected] (Matthew Hagerty) wrote in

You really think I could fix it? I'm certainly willing to try, it's
just a little intimidating. I will get a service manual, I've been
looking for a source all morning, could you perhaps suggest one?

Thanks,
Matthew

Well,I suspect you have a bad hybrid IC which may be difficult to get as
they are no longer made or even stocked by TEK.
The only source is from "parts scopes",to the best of my knowledge.

Sources?
Start with Ebay

Then;
(they may not be current)

MANUALS SOURCES

pdf-manuals.com

TEKtronix Manuals for free download, FYI:

http://www.datasouthservices.com/Manuals/
http://bama.sbc.edu



TECH SYSTEMS 1-800-435-1516
SYNERGETICS SURPLUS 520-428-4073
PEPPER SYSTEMS 214-353-0257
MANUALS PLUS 206-531-8031
US SURPLUS 410-750-1083
E-MAIL: [email protected]

Tektronix Used Manual Sources:
1. Deane Kidd 27270 SW Ladd Hill Road Sherwood, OR 97140, 503 625-
7363
(also has some parts)
2. Ed Matsuda, P.O. Box 390613, San Diego, CA 92149, 619 479-0225
voice, 619 479-1670 fax
3. Manual Merchant: Linda Perkins, PO Box 927792 San Diego CA 92192,
619-642-0785, -0885 fax, [email protected]
4. W7FG Vintage Manuals, 3300 Wayside Dr., Bartlesville, OK 74006,
800-807-6146
5. Manuals Plus, P.O. Box 549, TAD #601, Tooele, Utah 84074, (801)
882-7188, (801) 882-7195 Fax



http://www.yourmanualsource.com/search.htm
http://www.sarrio.com/sarrio/rsman3.html
http://www.w7fg.com/manual.txt

 

[Hugh Prescott]

TekScopes Yahoo group is your friend. Join uo and ask for help

Hugh

 

[Matthew Hagerty]

[email protected] (Matthew Hagerty) wrote in


Step one is to get a service manual.
Step two is to read the circuit description.(the whole thing)
Step three is to check the LV power suplies.

There are also fault codes in the SVC manual,that tell from what front
panel led being lit,what part of the scope has a problem.

I have received a service manual (seems to be one made for the
military) and began some troubleshooting. Following the main trouble
flowchart the first 5 or 6 questions ask "can you see this or that on
the display?", so my answer to all of these is all "no" since my
display is not working.

Finally it comes to the block where I was sure I would find a problem:
"Are the voltages at J119 in accordance with the table 5.1?"
Unfortunately *all* voltages were exactally on target, perfectally set
in the middle of the +- range. The +10V Ref is 10.0000 +- 0.0001.

The next step has me checking for a clock signal on the CPU on the
control board. The clock was there and working, as well as address
line activity, data bus activity, correct interrupt timing, etc.. I
set the NORM/DIAG jumper to DIAG and found a good binary count on the
address bus and the correct data byte on the data bus.

After that I have some problems with the procedure since the control
board I have appears to be newer than the one in the manual I have.
Seems the 74373's were replaced with 74573's as well as many other
IC's, and the part placement is all different. I guessed at the
buffers as best I could and they all seem to be working, along with
the address decoder. After that the procedure ends saying to replace
one or all of three IC's: the CPU and the two 74373's (573's on my
board.)

That does not make sense to me though, since they all appear to be
working fine. I'd rather swap the control board before attempting to
mess with replacing surface mount IC's, and I want to make darn sure
I'm replacing the correct part. Unfortunately I don't have spare
2465B parts just sitting around so I'm stalled.

Anyone have any suggestions as to what I might try?

Thanks!
Matthew

 

[TekMan]

I have received a service manual (seems to be one made for the
military) and began some troubleshooting. Following the main trouble
flowchart the first 5 or 6 questions ask "can you see this or that on
the display?", so my answer to all of these is all "no" since my
display is not working.

Finally it comes to the block where I was sure I would find a problem:
"Are the voltages at J119 in accordance with the table 5.1?"
Unfortunately *all* voltages were exactally on target, perfectally set
in the middle of the +- range. The +10V Ref is 10.0000 +- 0.0001.

The next step has me checking for a clock signal on the CPU on the
control board. The clock was there and working, as well as address
line activity, data bus activity, correct interrupt timing, etc.. I
set the NORM/DIAG jumper to DIAG and found a good binary count on the
address bus and the correct data byte on the data bus.

After that I have some problems with the procedure since the control
board I have appears to be newer than the one in the manual I have.
Seems the 74373's were replaced with 74573's as well as many other
IC's, and the part placement is all different. I guessed at the
buffers as best I could and they all seem to be working, along with
the address decoder. After that the procedure ends saying to replace
one or all of three IC's: the CPU and the two 74373's (573's on my
board.)

That does not make sense to me though, since they all appear to be
working fine. I'd rather swap the control board before attempting to
mess with replacing surface mount IC's, and I want to make darn sure
I'm replacing the correct part. Unfortunately I don't have spare
2465B parts just sitting around so I'm stalled.

Anyone have any suggestions as to what I might try?

Dear Matthew,


There is a "troubleshoot flow chart" that guides you through the area
"no visible display". in the manual.

I've seen never fail the cpu in the 2465Bs, so I recommend to check
the HV section before changing the main board.

According to your description, the HV section might have a problem
too. Any loose wires, connectors?
Is HV available ( please use HV probe and be VERY careful)?


If all this turns in a nightmare for you, don't desperate: I can offer
service in Germany an Italy, if you don't mind shipping.

hth,
Andreas

 

[Matthew Hagerty]

Dear Matthew,


There is a "troubleshoot flow chart" that guides you through the area
"no visible display". in the manual.

I've seen never fail the cpu in the 2465Bs, so I recommend to check
the HV section before changing the main board.

According to your description, the HV section might have a problem
too. Any loose wires, connectors?
Is HV available ( please use HV probe and be VERY careful)?


If all this turns in a nightmare for you, don't desperate: I can offer
service in Germany an Italy, if you don't mind shipping.

hth,
Andreas

Actually I've made some progress. Someone suggested I follow the
display diag flowchart because they had a similar problem. So I did.
I got to a step where is said to "turn grid bias R1878 full CW and
grid drive R949 full CW", but I could not find R949, so I just started
with the grid bias. I only had to turn it a little and my display
came back!

The display is pretty messed up, but I can see the error message:

TEST 05 FAIL 44

Here are two images, one of the error and one after I hit AB TRIG to
exit:

http://digitalstratum.com/tekscope/2465b_fail.jpg
http://digitalstratum.com/tekscope/2465b_norm.jpg

I started following the Error Message Diag flowchart and wound up at
the block that says: Refer to trigger error table at left to determine
probably cause. That table says failures for 04 or 44 are:

a. U2634A, U2235, or U500
b. Line Signal

I cannot find U2634A or U2235 on any schematic or in the part locator
tables, and I have no idea what Line Signal is. Is there any way I
can get this down to a single failed part?

Thanks,
Matthew

 

[Jim Yanik]

[email protected] (Matthew Hagerty) wrote in

Actually I've made some progress. Someone suggested I follow the
display diag flowchart because they had a similar problem. So I did.
I got to a step where is said to "turn grid bias R1878 full CW and
grid drive R949 full CW", but I could not find R949, so I just started
with the grid bias. I only had to turn it a little and my display
came back!

The display is pretty messed up, but I can see the error message:

TEST 05 FAIL 44

IIRC,this means a EAROM failure,the IC that stores all the cal constants.
(It's been awhile,though.)

This IC is on the processor board.

Here are two images, one of the error and one after I hit AB TRIG to
exit:

http://digitalstratum.com/tekscope/2465b_fail.jpg
http://digitalstratum.com/tekscope/2465b_norm.jpg

I started following the Error Message Diag flowchart and wound up at
the block that says: Refer to trigger error table at left to determine
probably cause. That table says failures for 04 or 44 are:

a. U2634A, U2235, or U500
b. Line Signal

I cannot find U2634A or U2235 on any schematic or in the part locator
tables, and I have no idea what Line Signal is. Is there any way I
can get this down to a single failed part?

Thanks,
Matthew

Line Signal is tapped off the PS(primary side);used for line triggering and
trigger cal on startup.