Tektronix 4014-1 troubleshooting advice - test-drb@ccmp.vtda.org

pontus＠Update.UU.SE

27 Mar 27 Mar

12:40 a.m.

Hi We have a 4014 at the computer club and that patterns looks very familiar. It usually clears after a minute or so. We have assumed it was normal and have not investigated. Congratulations on a nice find! I'm quite jealous. /P On Thu, Mar 26, 2015 at 10:03:03PM -0700, Josh Dersch wrote:

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Hi all -- Picked up a Tektronix 4014-1 terminal. It's in pretty good shape, nice and clean and it's in nearly-working condition except that the storage behavior isn't quite right. On power-up, write-through doesn't. (That is, characters don't get stored to the tube.) Clearing the display via the RESET/PAGE key clears a roughly elliptical region in the center of the display but leaves the outer edges a mess. The cleared region stores characters properly. You can see the overall effect here: http://yahozna.dyndns.org/scratch/tek4014/clear.jpg After a 2-3 minutes of warming up the area cleared by RESET/PAGE increases. I haven't run the terminal long enough to see if it eventually completely erases the screen (while the power supply appears to be within tolerances, I still need to rebuild/reform it so I'm not going to run it too long yet). So far everything else seems to be functioning properly, the cursor appears properly (and does not write through), input is accepted from the keyboard, etc. I've been reading through the service manual on Bitsavers and it describes a very in-depth alignment procedure which I'm prepared to go through (once I've got the power supplies rebuilt) but I thought I'd ask here if this problem rings any bells and if there's anything I should immediately suspect or adjust. You guys know everything :). Thanks as always for the advice, Josh

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elson＠pico-systems.com

9:05 a.m.

On 03/27/2015 12:03 AM, Josh Dersch wrote:

...

Hi all -- Picked up a Tektronix 4014-1 terminal. It's in pretty good shape, nice and clean and it's in nearly-working condition except that the storage behavior isn't quite right. On power-up, write-through doesn't. (That is, characters don't get stored to the tube.) Clearing the display via the RESET/PAGE key clears a roughly elliptical region in the center of the display but leaves the outer edges a mess. The cleared region stores characters properly. You can see the overall effect here: http://yahozna.dyndns.org/scratch/tek4014/clear.jpg After a 2-3 minutes of warming up the area cleared by RESET/PAGE increases. I haven't run the terminal long enough to see if it eventually completely erases the screen (while the power supply appears to be within tolerances, I still need to rebuild/reform it so I'm not going to run it too long yet).

Let it fully warm up. My guess is the cathodes in the flood guns are getting weak. Allowing them to fully warm up will probably help some. Also, as others have suggested, there may be some voltage adjustments that need to be set. But, the final adjustment is to set some of the voltages on the guns for optimum performance. there is a VERY critical adjustment of the flood guns (I think that's the right term) to get the storage to be stable as long as possible. Too much or too little flood beam causes the stored image to either bloom or fade. Then, the erase is performed by changing some voltage on the storage grid and pulsing the flood guns, and secondary emission (I think) erases the charge on the storage grid. It has been 30 years since I had to mess with a 4010/4014 series, but I THINK I still kind of remember how they work. Have you checked bitsavers for a manual? Jon

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isking＠uw.edu

28 Mar 28 Mar

12:16 p.m.

I've worked with (and on) one, but that was 35 years ago! It was nearly new?. On Fri, Mar 27, 2015 at 9:54 AM, Josh Dersch <derschjo at gmail.com> wrote:

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On 3/27/15 9:05 AM, Jon Elson wrote:

On 03/27/2015 12:03 AM, Josh Dersch wrote:

Hi all -- Picked up a Tektronix 4014-1 terminal. It's in pretty good shape, nice and clean and it's in nearly-working condition except that the storage behavior isn't quite right. On power-up, write-through doesn't. (That is, characters don't get stored to the tube.) Clearing the display via the RESET/PAGE key clears a roughly elliptical region in the center of the display but leaves the outer edges a mess. The cleared region stores characters properly. You can see the overall effect here: http://yahozna.dyndns.org/scratch/tek4014/clear.jpg After a 2-3 minutes of warming up the area cleared by RESET/PAGE increases. I haven't run the terminal long enough to see if it eventually completely erases the screen (while the power supply appears to be within tolerances, I still need to rebuild/reform it so I'm not going to run it too long yet). Let it fully warm up. My guess is the cathodes in the flood guns are

getting weak. Allowing them to fully warm up will probably help some. Also, as others have suggested, there may be some voltage adjustments that need to be set. But, the final adjustment is to set some of the voltages on the guns for optimum performance. there is a VERY critical adjustment of the flood guns (I think that's the right term) to get the storage to be stable as long as possible. Too much or too little flood beam causes the stored image to either bloom or fade. Then, the erase is performed by changing some voltage on the storage grid and pulsing the flood guns, and secondary emission (I think) erases the charge on the storage grid. It has been 30 years since I had to mess with a 4010/4014 series, but I THINK I still kind of remember how they work. Have you checked bitsavers for a manual?

Yes, as I said I've been studying the service manual (on Bitsavers), which in typical Tek fashion is extremely detailed and helpful. It outlines the whole alignment procedure, but I figured I'd ask here first -- since this is a nearly 40-year-old terminal I'm interested to know if anyone on the list has dealt with similar issues and if there might be common failure points to check out before trying to re-align the thing. Thanks! Josh

Jon

-- Ian S. King, MSIS, MSCS, Ph.D. Candidate The Information School <http://ischool.uw.edu> Archivist, Voices From the Rwanda Tribunal <http://tribunalvoices.org> Value Sensitive Design Research Lab <http://vsdesign.org> University of Washington There is an old Vulcan saying: "Only Nixon could go to China."

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derschjo＠gmail.com

2 Apr 2 Apr

12:56 a.m.

On 3/30/15 12:08 AM, Simon Claessen wrote:

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we have a working 4002a in our museum and I always let it warm up with a completely illuminated screen for a minute or 5 before clearing the tube for the first time. that seems to do the trick.

I finished restoring the 4014's power supply this evening and as a few of you suggested, leaving it to warm up for a few minutes seems to do the trick; after 3-5 minutes the screen clears fully and everything works as expected -- the stored characters stay crisp (they don't bloom or fade) and the picture is nice and bright. So that's good! Probably a few things are a bit out of tolerance, but I'll accept this behavior rather than risk making things worse by trying to recalibrate it :). Tomorrow (er, later today, I suppose) I'll actually hook it up to a computer and throw some graphics at it... Thanks all! Josh

...

On 27-03-15 06:03, Josh Dersch wrote:

Hi all -- Picked up a Tektronix 4014-1 terminal. It's in pretty good shape, nice and clean and it's in nearly-working condition except that the storage behavior isn't quite right. On power-up, write-through doesn't. (That is, characters don't get stored to the tube.) Clearing the display via the RESET/PAGE key clears a roughly elliptical region in the center of the display but leaves the outer edges a mess. The cleared region stores characters properly. You can see the overall effect here: http://yahozna.dyndns.org/scratch/tek4014/clear.jpg After a 2-3 minutes of warming up the area cleared by RESET/PAGE increases. I haven't run the terminal long enough to see if it eventually completely erases the screen (while the power supply appears to be within tolerances, I still need to rebuild/reform it so I'm not going to run it too long yet). So far everything else seems to be functioning properly, the cursor appears properly (and does not write through), input is accepted from the keyboard, etc. I've been reading through the service manual on Bitsavers and it describes a very in-depth alignment procedure which I'm prepared to go through (once I've got the power supplies rebuilt) but I thought I'd ask here if this problem rings any bells and if there's anything I should immediately suspect or adjust. You guys know everything :). Thanks as always for the advice, Josh

Reply