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Arrived from a friend before 1 week. Problem shown on the video.
I changed up to now the following components with another 2445, as to check what work and what not. All the above work good.
1. PSU
2. Controller board.
3. Readout board.
4. Front controls board.
5. All the hybrid ic's.
6. Display Sequencer.
The PSU output voltages is at specified range. Intensity control not setting down full the beam.
Have someone an idea where to start looking? I mean with the measurements..
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You forgot the video link?
Albert
---In TekScopes@..., <sadosp@...> wrote :
Arrived from a friend before 1 week. Problem shown on the video.
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Hi Albert. Sorry for that. :-(
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You should go through the CRT adjustments section of the calibration in the service manual.
It looks like the beam current is too high.
Tom
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----- Original Message -----
From: sadosp@... [TekScopes]
To: TekScopes@...
Sent: Friday, December 12, 2014 12:48 PM
Subject: [TekScopes] Re: TEK 2465 with screen issues.
Hi Albert. Sorry for that. :-(
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Hi Tom. You believe cause is only a re calibration problem? Ok recently bought the needed tools, plus extras (attenuators, terminators etc.) I can not find the tunnel diode pulser only, at an affordable price.
Fortunately a friend who has it, could I lend.
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Hi Panos,
At least turn down the Grid bias control so you don't burn the screen. It's in the Alignment procedures section, R-1878 on the left side of the scope and inside the HV cover. It should be marked "Grid". Set the scope per the instructions.
It's good that you can access all the equipment to do the calibration. A great scope for sure.
Tom
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----- Original Message -----
From: sadosp@... [TekScopes]
To: TekScopes@...
Sent: Friday, December 12, 2014 1:18 PM
Subject: [TekScopes] Re: TEK 2465 with screen issues.
Hi Tom. You believe cause is only a re calibration problem? Ok recently bought the needed tools, plus extras (attenuators, terminators etc.) I can not find the tunnel diode pulser only, at an affordable price.
Fortunately a friend who has it, could I lend.
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Yes Tom you have right about the phosphor. Till now power on this oscilloscope (to check it) very few minutes. After your tip (although the problem remains) can use it without any fear.
I will take some readings from A9 high voltage board (low stages), just to see if according with service manual waveform.
Panos
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Could be Z-Axis amplifier & blanking trouble, perhaps? Feed the calibrator in and check whether you see the beam on retrace. Put the scope in chop mode and check whether you see the beam alternating between the displayed traces during sweeps.
The chop frequency is between 1-2.5MHz, depending on the sweep speed, so sweeps upward of 1us is where you'd see this well (I think).
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Hi Tinkerer. Returned back here to tell the good news, just see your message. Thank you very much for those information's.
Finally the problem was a bad solder point on the "high voltage regulator" stage. This was a unconnected but very well hidden edge of resistor, between the R1922 - R1913 - CR1915 components. In the picture above I have separate it, so that you can see better.
I discover this when I was ready to take the No 73 measure, which is at this point. Unconnected pin was moved, and oscilloscope began to show perfect.
Also I take one more video, in order to see one more problem at the bottom of the screen. I speak for these little dots on readout. Have something to do with calibration? Or its one more problem with oscilloscope?
Thank you all....Panos.
;sortOrder=asc&photoFilter=ALL#zax/1562274356
;feature=youtu.be ;feature=youtu.be
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Finally the problem was a bad solder point on the "high voltage regulator" stage. This was a unconnected but very well hidden edge of resistor, between the R1922 - R1913 - CR1915 components. In the picture above I have separate it, so that you can see better. I discover this when I was ready to take the No 73 measure, which is at this point. Unconnected pin was moved, and oscilloscope began to show perfect. Interesting - looks like this was a cold joint on one of those bodge joins? I remember seeing those bodges all over my 2465, not so much on the 2467. Also I take one more video, in order to see one more problem at the bottom of the screen. I speak for these little dots on readout. Have something to do with calibration? Or its one more problem with oscilloscope? I got nothing - have you tried switching the readout boards again?
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Many times I have repaired very valuable test instruments that were completely disabled by a single bad solder joint. The component lead would be making a physical contact at the time of manufacture and worked perfectly well at the factory, but over many years the atmosphere would permeate the joint and cause a corroded Open condition. I am not talking about a classical "cold" solder joint which can be detected with a visual inspection. These Open fixes usually require circuit analysis and probing. It is a great feeling to bring something back to life. On Dec 12, 2014 6:33 PM, "siggi@... [TekScopes]" < TekScopes@...> wrote:
Finally the problem was a bad solder point on the "high voltage regulator" stage. This was a unconnected but very well hidden edge of
resistor, between the R1922 - R1913 - CR1915 components. In the picture
above I have separate it, so that you can see better.
I discover this when I was ready to take the No 73 measure, which is at this point. Unconnected pin was moved, and oscilloscope began to show
perfect.
Interesting - looks like this was a cold joint on one of those bodge
joins?
I remember seeing those bodges all over my 2465, not so much on the 2467.
Also I take one more video, in order to see one more problem at the bottom of the screen. I speak for these little dots on readout. Have
something to do with calibration? Or its one more problem with
oscilloscope?
I got nothing - have you tried switching the readout boards again?
[Non-text portions of this message have been removed]
[Non-text portions of this message have been removed]
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Garry wrote.... It is a great feeling to bring something back to life. Yes indeed! :-) Tinkerer138 wrote... > I got nothing - have you tried switching the readout boards again? No I didn't. I believe cause oscilloscope have lost some of its calibration data. Worse yet, maybe the EAROM ic has reached the end of his life, and isn't possible to store data on some memory areas. I read somewhere for a guy who try to calibrate his oscilloscope, and at some point of vertical cal theEAROM ic not save the data, but give a message "limit" or something. 2 known ic of this type (1400 byte) exist, one of General Instrument ER1400, and one more from Mitsubishi M5G1400. My first 2445 have the first, and this one 2465 have the second. Panos.
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The calibration procedure is tricky but if you think the problem is with the
EAROM, I have seen the ER1400 for sale on Ebay for reasonable prices.
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On 13 Dec 2014 01:05:20 -0800, you wrote: No I didn't. I believe cause oscilloscope have lost some of its calibration data. Worse yet, maybe the EAROM ic has reached the end of his life, and isn't possible to store data on some memory areas.
I read somewhere for a guy who try to calibrate his oscilloscope, and at some point of vertical cal theEAROM ic not save the data, but give a message "limit" or something.
2 known ic of this type (1400 byte) exist, one of General Instrument ER1400, and one more from Mitsubishi M5G1400.
My first 2445 have the first, and this one 2465 have the second.
Panos.
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I believe cause oscilloscope have lost some of its calibration data. Worse yet, maybe the EAROM ic has reached the end of his life, and isn't possible to store data on some memory areas. I'd still bet on the readout board. I count 32 characters and dots across the screen, which corresponds to the number of character positions in the readout machinery. Maybe your character RAM is failing, or perhaps there's something else in the readout machinery that erroneously displays a dot instead of space in that row. An easy thing to try is to enable the second/third/fourth channels and play with 50Ohm/DC/AC termination to see what happens to those character positions when they're written to. Turn the channels back off and see whether these positions revert to dots or to spaces.
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Hi Panos,
Before you do anything else, read up in the maintenance section about the Cycle error clear (exerciser 03) process. In my manual, it starts on page 6-16. You will need to place the cal-no.cal jumper in the cal position to run that process.
Regards,
Tom
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----- Original Message -----
From: sadosp@... [TekScopes]
To: TekScopes@...
Sent: Saturday, December 13, 2014 4:05 AM
Subject: [TekScopes] Re: TEK 2465 with screen issues.
Garry wrote....
> It is a great feeling to bring something back to life.
Yes indeed! :-)
Tinkerer138 wrote...
> I got nothing - have you tried switching the readout boards again?
No I didn't. I believe cause oscilloscope have lost some of its calibration data. Worse yet, maybe the EAROM ic has reached the end of his life, and isn't possible to store data on some memory areas.
I read somewhere for a guy who try to calibrate his oscilloscope, and at some point of vertical cal theEAROM ic not save the data, but give a message "limit" or something.
2 known ic of this type (1400 byte) exist, one of General Instrument ER1400, and one more from Mitsubishi M5G1400.
My first 2445 have the first, and this one 2465 have the second.
Panos.
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Hi tinkerer. I try what you suggest, and the result was to see the characters for each channel etc. But when turn the channels back, character disappear and dot return back on its position.
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Thanks for the info about EAROM David.
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Hi Tom. Just see your message. I will try it, and respond back here.
Panos.
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Hi sadosp Try again and look closely; are the characters you turned on with ch 3,4 positioned exactly over the dots?
I think tinkerer suggested this test as a diagnostic, not a repair, reset or fix. If these dots are in tyhe same position as some of the screen text, it will point one way and if not maybe another.
Also it isn't clear; did the dots in-between groups of screen text disappear when the text was displayed?
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I think tinkerer suggested this test as a diagnostic, not a repair, reset or fix. If these dots are in tyhe same position as some of the screen text, it will point one way and if not maybe another. Yeah, that's the idea. I'd be very surprised if EAROM failure manifested this way. I'd expect the scope to fail POST with 04-level errors, as there's checksumming over the EAROM contents. In your video, you're turning the scope on, and it's not failing self tests, which leads me to believe the error is not in the EAROM, nor in any of the other myriad things that the power on self tests (POSTs) cover. Come to think of it, there is a POST for the readout RAM (see test 03), where the CPU writes to the character RAM and then reads back to check the RAM. So, if this is a readout board error, it's presumably downstream from the readout character ROM. Since you have a 2445 with a compatible readout board, why not try to swap them, see what happens? $5 says your error is going to vanish :).
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@Tom
I try the "Cycle Test" with "ALL PASS" as a result. Also make the error clear process. Nothing change!
The manual says cause if you have some error there, a diagonal line on the screen appear.
I haven't any diagonal line on my case.
@iamachine
Every dot is one of the lower part of character, in exact place in between groups at bottom of screen, who text disappear. All the characters appear in place of dots (not left or right), when some button pressed. For example ch3 or ch4 or ch2 or 20 Mhz bw limit etc.
Panos.
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Gary Robert Bosworth
David Hess