Date   

Re: 2430A Fails Repet

Rich Frahm
 

That is with no input at all. Nothing connected to either channel, nothing connected to either trigger. I expect to see a nice straight solid line.

Rich


Re: 2430A Fails Repet

Siggi
 

This photo doesn't tell the whole story. What's the input signal and the
settings of the scope at large? What were you expecting to see?

On Tue, Mar 31, 2020 at 10:52 AM Rich Frahm <criageek@gmail.com> wrote:

Ah...thanks for the info Siggi. Here you go:
https://drive.google.com/file/d/1qw72EvsznoUFpUxSSReYg4XRwzbzA6a4/view?usp=sharing

Rich




Re: 2430A Fails Repet

Rich Frahm
 


Re: 2430A Fails Repet

Siggi
 

Hey Rich,

your photo didn't make it - this forum doesn't allow attachments. Best
thing to do is to upload it to a photo album and link it from there.

Siggi

On Tue, Mar 31, 2020 at 9:44 AM Rich Frahm <criageek@gmail.com> wrote:

Thanks Siggi - I will try again, but have done it a few times. I also
meant to mention in my previous post that the chopped display I am seeing
is on both channels.

Rich




Re: 2782 electrical schematics

Bob Koller <testtech@...>
 

Schematics are available on ko4bb.com.


Re: 2782 electrical schematics

Tony Fleming
 

Ernesto, you are right, but today everything is DISPOSABLE and people buy a
new instrument rather than fix it. Manufactures are keeping everything
inexpensive so fixing today is more expensive, that is why people just dump
stuff!
I love older stuff that we can fix today, but our new stuff isn't gonna
make it in 30+ years in the future, since it is all disposable design!
By same token the future is so unpredictable that we can't even imagine it.
The instruments are gonna bee completely different and who knows, maybe
self-fixing technology! ha ha ha
I love progress but older Tektronix scope is just so well made and
repairable, serviceable .... I love the machines made this way.

On Tue, Mar 31, 2020 at 9:28 AM Ernesto <ebordon@swbell.net> wrote:

Hi Dale,

I agree. I would also use for work only older Tektronix and HP equipment
that is serviceable. Like I would stay away from cars that don't offer to
the owners some service information that allows them to repair the car
themselves.
I see absolutely no reason for Tektronix not to publish the circuit
diagram of the 2782 CRT HV supply, so that evdsp39 can fix what is wrong
with it. This has nothing to do with "instrumentation needed to service
it". And the CRT interface has nothing mysterious that can be a trade
secret,
When I see the later Tektronix service manuals that hide information like
this, or pot together components to make them unnecessarily proprietary, I
get ready to send to hell any loyalty, appreciation, respect for the brand.
I still keep these for the "old Tektronix", but, if I would fancy a new
digital oscilloscope, I would buy an inexpensive one sold by Amazon, even
if they may be some "inferiority", and snub Tektronix. After all, there
is no reason why others cannot make electronic instruments.




Re: 2782 electrical schematics

 

Hi Dale,

I agree. I would also use for work only older Tektronix and HP equipment that is serviceable. Like I would stay away from cars that don't offer to the owners some service information that allows them to repair the car themselves.
I see absolutely no reason for Tektronix not to publish the circuit diagram of the 2782 CRT HV supply, so that evdsp39 can fix what is wrong with it. This has nothing to do with "instrumentation needed to service it". And the CRT interface has nothing mysterious that can be a trade secret,
When I see the later Tektronix service manuals that hide information like this, or pot together components to make them unnecessarily proprietary, I get ready to send to hell any loyalty, appreciation, respect for the brand. I still keep these for the "old Tektronix", but, if I would fancy a new digital oscilloscope, I would buy an inexpensive one sold by Amazon, even if they may be some "inferiority", and snub Tektronix. After all, there is no reason why others cannot make electronic instruments.


Re: 2400 series Test 4 Fail 3,13, 2

Chuck Harris <cfharris@...>
 

Hi Craig,

If the scope was not showing the "11" code, through several
power cycles, and then suddenly it did, the obvious conclusion
is that something in the RAM unexpectedly changed.

This could be a bad RAM, but I really doubt it.

It could be a bad/intermittent connection to the RAM, which is
quite likely. I have seen some customer replaced NVRAM modules
(later scopes), where the customer cut through traces while doing
the desoldering operation... (eg. got too rough).

It could be a flaw in the cutover between battery and mains power.

It is important that the RAM not get written to while the data
lines are in an indeterminate state while 5V is coming on, and cutting
off.

So, I would look carefully at the circuitry comprised of Q2070, Q2170,
Q2270, Q2370, and Q2470. They are there to make sure that the chip
select pin on the RAM is safely parked away in the unselected condition
while power is unstable.

And, I would look at the traces on the bottom of the board about a
desoldering tip diameter around each of the pins on the RAM chip.
An ohmmeter can help.

-Chuck Harris

Craig Cramb wrote:

This is a pretty long feed that tarted back in January. Lots of good info thur-out this.
I finally got back started again with all the sit at home time. The 2465B s/n B010817 I got a correct replacement for the U2460 and BT2570 and installed the a couple of months ago. Waited until this last week to continue. Monitored the Battery and U2460 input voltage over the last 2 months to verify that the chip wasn't draining the battery as before in this feed. All was ok so this past went thru a complete calibration and all seemed to go well. Put scope aside for a week and then restarted it today. Now I get the Test04 fail 11. Does this seem to be that there is another chip failure or is this just a point in the calibration that wasn't correct?




Re: 2430A Fails Repet

Rich Frahm
 

Thanks Siggi - I will try again, but have done it a few times. I also meant to mention in my previous post that the chopped display I am seeing is on both channels.

Rich


Re: 2430A Fails Repet

Siggi
 

Hey Rich,

It's been a few years since I resurrected my 2430 so my memory is a little
hazy, but I remember needing to cold start and self cal twice after battery
loss before it came to its senses. I went through this a couple of times,
and I remember thinking how strange that was.

Siggi

On Tue, Mar 31, 2020 at 9:35 AM Rich Frahm <criageek@gmail.com> wrote:

Thanks Szabolcs - I did do a cold start and self and ext cal...that's how
I know it fails repet, which is in the ext cal. Sorry, I should have been
clearer. The 9113 failure is for channel 1 and the 0123 is for channel 2,
so both fail that. There is only one 9300 test, so affects both channels.

Rich




Re: 2430A Fails Repet

Rich Frahm
 

Thanks Szabolcs - I did do a cold start and self and ext cal...that's how I know it fails repet, which is in the ext cal. Sorry, I should have been clearer. The 9113 failure is for channel 1 and the 0123 is for channel 2, so both fail that. There is only one 9300 test, so affects both channels.

Rich


Re: Tek 475 strange sweep behavior

Tom Gardner
 

Do you mean 1ms or 10ms? The video can be interpreted as 10ms and slower.

I would start by looking at anything and everything connected to the timebase selection control, including

- timebase switch mechanism to check it is still rotating sensibly and the finger contacts are moving reliably
- the finger contacts, carefully cleaning them in the standard way
- the resistors/capacitors associated with the faulty timebases
- connections going elsewhere in the scope (no, that isn't a strength of Tek scopes!)

In particular at 10ms I note that cam switches 17 and 4 (especially) and 2 are closed, unlike at faster sweeps. If those switches are OK then the components connected to those may be faulty.

On 31/03/20 12:55, unclebanjoman wrote:
Hi all,
I've receveid an help request from a friend of mine.

It owns a decent 475 that exhibits this strange behavior with the main sweep ("A"). with trigger in AUTO, the waveform from the calibrator disappears when the time/div drops below 1 ms/div and you only see a brilliant compressed waveform at the extreme right of the screen.

Never seen such behavior. I don't know what to suggest to him.
In the video

https://drive.google.com/file/d/1ecqsZQnl9midnmXYC56J9kTYA8nkdcsS/view?usp=sharing

he shows both the 475 calibrator waveform applied on CH1 and the trigger signal on test point 572, displayed using another scope.

Any suggestion?

I've never seen a such behavior.....
Thank you,


Re: 2782 electrical schematics

Dale H. Cook
 

On 3/30/2020 11:50 PM, Ernesto wrote:

The manual in tekwiki has also plenty of block diagrams but no circuit diagrams. (has Tektronix decided that circuit diagrams are obsolete??)
No, but field service for many relatively recent instruments is obsolete, as it requires instruments generally not available to those who wish to perform field service. That is why I use a number of older HP and Tek instruments in the field and in the shop for my work - I have the instrumentation needed to service them.
--
Dale H. Cook, Radio Contract Engineer, Roanoke/Lynchburg, VA
https://plymouthcolony.net/starcityeng/index.html


Tek 475 strange sweep behavior

unclebanjoman
 

Hi all,
I've receveid an help request from a friend of mine.

It owns a decent 475 that exhibits this strange behavior with the main sweep ("A"). with trigger in AUTO, the waveform from the calibrator disappears when the time/div drops below 1 ms/div and you only see a brilliant compressed waveform at the extreme right of the screen.

Never seen such behavior. I don't know what to suggest to him.
In the video

https://drive.google.com/file/d/1ecqsZQnl9midnmXYC56J9kTYA8nkdcsS/view?usp=sharing

he shows both the 475 calibrator waveform applied on CH1 and the trigger signal on test point 572, displayed using another scope.

Any suggestion?

I've never seen a such behavior.....
Thank you,
Max


Re: 2782 electrical schematics

 

Hi evdsp39,

The manual in tekwiki has also plenty of block diagrams but no circuit diagrams. (has Tektronix decided that circuit diagrams are obsolete??)

Did you get any response from the poster who has the circuit diagram at the other site you consulted,

https://forum.tek.com/viewtopic.php?t=135234&__cf_chl_jschl_tk__=dc56ddefd230acd93f9df188b708ab0c7f1bdfa0-1585625507-0-AUli2D36HpqZDRXn-ihg6gHacpOqzFNHDEmQrYFNPgH_kJ1htEG_qitoaRsN4qbrGkD5fIWZJ1M6hMcEmlFPd0e_fuHtwnO6JRYC7tWT1wsyLjOQb2qvBAe7RyDbn_K2OaWiz5NRRkNsF-6gZEaB_pAS__bQWkaY2o_40rHanBMI_pNg1bW9owRlllUguzCobQeejkSWAYd1ozrG91kGPa3l5LXoPR-CPDZtysPYAiCqinX-KAYDvIbupKa9fx6D6cEc5JdnIgOR6v1MeJX247DzL2FhBntGoq2MD5G8r_IJXiClcJIZ0BgvzFQg15tl90N_vf8sr6ExdFwBanxERAg5ONkr-4uTXrNdWZkG512H ?

When you say that focus, astigmatism and intensity are not working, does this mean that the tube seems to be dead?
If you find no circuit diagrams, can you go into the instrument and measure the voltages at the CRT, probably wrong or missing, and improvise a traditional high voltage supply for this CRT that at least lets you see something on its screen?


Re: 2400 series Test 4 Fail 3,13, 2

Craig Cramb
 

This is a pretty long feed that tarted back in January. Lots of good info thur-out this.
I finally got back started again with all the sit at home time. The 2465B s/n B010817 I got a correct replacement for the U2460 and BT2570 and installed the a couple of months ago. Waited until this last week to continue. Monitored the Battery and U2460 input voltage over the last 2 months to verify that the chip wasn't draining the battery as before in this feed. All was ok so this past went thru a complete calibration and all seemed to go well. Put scope aside for a week and then restarted it today. Now I get the Test04 fail 11. Does this seem to be that there is another chip failure or is this just a point in the calibration that wasn't correct?


Re: Tektronix 2445A slow startup

Steve
 

Thank you Victor for the info and reply! out of curiosity, I found that mouser carries the internal battery but from what I've read so far they seem bo last quite a long time. Should I just check and replace if voltage is @ 3.1vdc or lower or just replace as preventative maintenance?

--
Kind Regards,

steve


Re: Tektronix 2235A

Bill
 

Yes USD.Bill

On Monday, March 30, 2020, 04:57:01 PM CDT, Roy Thistle <roy.thistle@mail.utoronto.ca> wrote:

Hi Bill:
A fair offer where? (Some said 150.00... but... is that USD?... I assume it is.. but, assumptions often make of me something I don't want to be!)
Best regards and wishes.
Roy


Re: Tektronix 2235A

Roy Thistle
 

Hi Bill:
A fair offer where? (Some said 150.00... but... is that USD?... I assume it is.. but, assumptions often make of me something I don't want to be!)
Best regards and wishes.
Roy


Re: 2430A Fails Repet

Szabolcs Szigeti
 

Hi,

Remove, clean an reseat the hybrid circuits. Look at the details in the
extended diagnostics. If it is one channel that fails, you can swap the ICs
to find if any of them id bad. Although I'm not sure if hhere is two ore
one trigger modules in this model.
Also, do a cold start then try self and ext cal.

Szabolcs

Rich Frahm <criageek@gmail.com> ezt írta (időpont: 2020. márc. 30., Hét
21:47):

I recently picked up a Tektronix 2430A for next to nothing because it
had failures on the self test. Most of these failures were caused by a
dead backup battery. I found a suitable replacement and installed it and
that got me past most of the failures. It still failed 9000 Trigs on the
extended diagnostics. I did the ext cal on the atten, triggers, and
repet...atten and triggers passed, but repet failed. I opened it up and
looked it over carefully and found an electrolytic cap on the low
voltage power supply board that was bulged on top, so I removed it and
tested it. It was a 2200uF cap that read 15uF, so I ordered and replaced
all electrolytics on the low voltage power supply board but it made no
difference. It still has these failures:

9113 Slope
9123 Slope
9300 Trigs/Repet

And I don't have a nice straight trace...this is what I have:

display_006_r.jpg

The displays changes as it should when the time base is changed but not
when the volts/div is changed, even though the readout showing the
setting it's on does change as it should.

Can someone point me in the right direction on this? I do have a pdf of
the service manual. If this requires special test equipment to
troubleshoot I'm probably out of luck. I'm just a hobbyist and my test
equipment consists of a Tektronix 2215 (which I bought new when they
first came out in the mid to late 80s), a Fluke 77 (also purchased new
in the early to mid 80s), a couple more meters, a couple of signal
generators, a couple of power supplies...that's about it.

Thanks,
Rich



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