Topics

577 D1 function won't turn off

DW
 

This 577 is a D1 version, the ability to temporary hold display information in a analog format which is actually quite neat.

This feature appears to be fully function when I want to use it, the problem is when I don't want to use it I can't seem to get it to turn off!

What I am experiencing is a ghosting effect (seems partially on), it is most noticeable with the intensity turned up but minimal when down. The retention seems short, ghosting disappears although some might stay retained on the screen. Using the clear button with the upper or lower pressed appears to temporarily fix this. I also find when I power on the instrument two big round circles appear on the display and then gradually fade but doesn't disappear entirely until cleared.

Mlynch001
 

I would certainly check that the store/non store switch is actually latching and unlatching properly. This may seem obvious, however, I have seen many of these type of switches that were gummed up or victims of corrosion therefore, not latching or making proper contact. Also perform the storage calibration checks and procedures outlined in the manual, Sec. 8 Adjustments Section. Also check Q1396, VR1396 and their related components for proper voltages and failures. I have a 577D2 that has been converted to a D1, I am following your posts regarding your troubles.

Good Luck
--
Michael Lynch
Dardanelle, AR

 

Hi DW,
I have a 577 D1 which has similar behavior but not as bad as you described. There is an adjustment procedure in the service manual that will, in theory, bring the storage back into proper operation. I found the procedure difficult to follow and several of the adjustments seemed to have little effect. I wasn't satisfied with the results from following the step by step procedure in the service manual.

After going through the procedure in the service manual several times I felt like nothing I might do could make things any worse so I took matters into my own hands and fiddled with the adjustments now that I knew more about what they were supposed to do and what effect they were supposed to have.

In the end I did improve the storage to where it worked well enough that I was satisfied with it. There were two things I was unable to adjust properly. The first occurs when I turn the 577 on. As the CRT warms up the storage gun partially floods the screen and I have to press the erase buttons to clear this. After I do that the storage seems to behave itself. The other one is the storage Brightness knob doesn't seem to do anything.

I still don't know if I wasn't following the procedure in the manual properly or if I have a problem in the storage circuitry of the 577 that I need to troubleshoot.

Dennis Tillman W7PF

-----Original Message-----
From: DW
Sent: Friday, December 06, 2019 8:38 PM
Subject: [TekScopes] 577 D1 function won't turn off

This 577 is a D1 version, the ability to temporary hold display information in a analog format which is actually quite neat.

This feature appears to be fully function when I want to use it, the problem is when I don't want to use it I can't seem to get it to turn off!

What I am experiencing is a ghosting effect (seems partially on), it is most noticeable with the intensity turned up but minimal when down. The retention seems short, ghosting disappears although some might stay retained on the screen. Using the clear button with the upper or lower pressed appears to temporarily fix this. I also find when I power on the instrument two big round circles appear on the display and then gradually fade but doesn't disappear entirely until cleared.




--
Dennis Tillman W7PF
TekScopes Moderator

Dave Voorhis
 

I have a 577 D1 that came with the original but weak CRT installed and a replacement CRT in a box. Storage mode on the original weak CRT worked well, but the primary trace was almost too dim to see.

I installed the replacement CRT. It's bright and sharp, but storage mode now doesn’t work at all. Thinking that I might have inadvertently nuked something in the storage circuitry during the CRT replacement, I temporarily jury-rigged the old CRT to verify that the storage mode still worked. It did.

I haven’t yet done the adjustment procedure, as the storage mode isn’t that important to me at the moment, but I will.

Question: is it typical for the storage settings to be critical enough and/or vary enough from CRT to CRT, for storage mode to work well on one CRT and not at all on another?

On 7 Dec 2019, at 05:50, Dennis Tillman W7PF <@Dennis_Tillman_W7PF> wrote:

Hi DW,
I have a 577 D1 which has similar behavior but not as bad as you described. There is an adjustment procedure in the service manual that will, in theory, bring the storage back into proper operation. I found the procedure difficult to follow and several of the adjustments seemed to have little effect. I wasn't satisfied with the results from following the step by step procedure in the service manual.

After going through the procedure in the service manual several times I felt like nothing I might do could make things any worse so I took matters into my own hands and fiddled with the adjustments now that I knew more about what they were supposed to do and what effect they were supposed to have.

In the end I did improve the storage to where it worked well enough that I was satisfied with it. There were two things I was unable to adjust properly. The first occurs when I turn the 577 on. As the CRT warms up the storage gun partially floods the screen and I have to press the erase buttons to clear this. After I do that the storage seems to behave itself. The other one is the storage Brightness knob doesn't seem to do anything.

I still don't know if I wasn't following the procedure in the manual properly or if I have a problem in the storage circuitry of the 577 that I need to troubleshoot.

Dennis Tillman W7PF

-----Original Message-----
From: DW
Sent: Friday, December 06, 2019 8:38 PM
Subject: [TekScopes] 577 D1 function won't turn off

This 577 is a D1 version, the ability to temporary hold display information in a analog format which is actually quite neat.

This feature appears to be fully function when I want to use it, the problem is when I don't want to use it I can't seem to get it to turn off!

What I am experiencing is a ghosting effect (seems partially on), it is most noticeable with the intensity turned up but minimal when down. The retention seems short, ghosting disappears although some might stay retained on the screen. Using the clear button with the upper or lower pressed appears to temporarily fix this. I also find when I power on the instrument two big round circles appear on the display and then gradually fade but doesn't disappear entirely until cleared.

--
Dennis Tillman W7PF
TekScopes Moderator

Mlynch001
 

Question: is it typical for the storage settings to be critical enough and/or vary enough from CRT to CRT, for storage mode to work well on one CRT and not at all on another?<
Dave,

Yes, I believe that this is exactly what you are experiencing. According to the Service manual, replacing the CRT will require the Storage circuit to be adjusted to match the characteristics of the new CRT. I don't think that you "nuked" anything, but that you will find that the circuit is so far out of adjustment that your storage simply will not work properly. And, as Dennis Mentioned, the adjustment procedure as described in the manual is NOT very easy to follow. And if Dennis has trouble following the procedure, I am not sure what that means for us mere mortals.

--
Michael Lynch
Dardanelle, AR

 

Hi Dave,
Was the replacement CRT a new CRT? If not new how do you know it was any good in the first place?
Dennis Tillman W7PF

<SNIP>

-----Original Message-----
From: Dave Voorhis
Sent: Saturday, December 07, 2019 4:47 AM
Subject: Re: [TekScopes] 577 D1 function won't turn off

I have a 577 D1 that came with the original but weak CRT installed and a replacement CRT in a box. Storage mode on the original weak CRT worked well, but the primary trace was almost too dim to see.




--
Dennis Tillman W7PF
TekScopes Moderator

Dave Voorhis
 

It is a used CRT that the previous owner was told was extracted from a working unit, though “working” may or may not have included storage. The previous owner of my 577 didn’t know.

And that’s the reason for my question — before I (eventually) launch into storage calibration, I want to know whether or not it’s reasonable for the storage calibration settings that work for one CRT not to work for another. If it's typical for D1 CRTs to be interchangeable and the storage to essentially work — though perhaps not optimally — I’ll keep my eye out for another replacement.

Instead, if it’s typical (or at least reasonable) for changing the CRT to result in non-storage condition then I'll only look for a replacement CRT once I confirm it’s defective, if it is. ‘Erase’ does appropriately “green" the screen so I presume at least the flood guns are working.

On 7 Dec 2019, at 17:34, Dennis Tillman W7PF <@Dennis_Tillman_W7PF> wrote:

Hi Dave,
Was the replacement CRT a new CRT? If not new how do you know it was any good in the first place?
Dennis Tillman W7PF

<SNIP>
-----Original Message-----
From: Dave Voorhis
Sent: Saturday, December 07, 2019 4:47 AM
Subject: Re: [TekScopes] 577 D1 function won't turn off

I have a 577 D1 that came with the original but weak CRT installed and a replacement CRT in a box. Storage mode on the original weak CRT worked well, but the primary trace was almost too dim to see.




--
Dennis Tillman W7PF
TekScopes Moderator


 

Hi Dave,
I have probably used at least fifty Tek scopes in my lifetime but fewer than five storage scopes or curve tracers. The first time I tried using storage was on an almost new 549 in 1968. I remember thinking to myself that storage was better than nothing at all but it wasn't all I hoped for. Two things contributed to that impression: The stored traces would bloom, and the storage was hard to control. In the years since then I have learned to settle for what I get on Tek storage scopes instead of being pleased with the results.

I use my 577-D1 a lot and I frequently need to store the results. At one point I got annoyed with the results and decided that calibrating the storage circuitry according to the manual could only improve things. Since this was the first time I ever adjusted a storage scope I cannot say whether the directions were confusing to follow or whether I found them confusing. I was also surprised that many of the adjustment steps seemed to interact with each other or seemed to do nothing at all. After doing the best I could to follow the written directions it was hard to tell that I had made much difference at all. At that point I just ignored the directions as I tried adjusting the pots for what I thought was the best result.

Looking back there are several possible explanations for why I wasn't able to improve my 577-D1 as much as I had hoped.
1) I have limited experience with storage technology.
2) I don't understand the limitations of storage technology.
3) My expectations for storage are unrealistic.
4) I did not understand the calibration procedure.
5) I have a problem following directions (a recurring issue in my life).
6) The particular CRT I was trying to adjust was getting old or worn out.

I do know enough about storage that it is important to go through the cal procedure when you change the CRT. The cal procedure shouldn't take you as much time as it took to change the CRT. It may provide answers to at least some of the things I listed above. I'm starting to think that if I can find the time it would be worth recalibrating my 577-D1 storage again.

Dennis Tillman W7PF

-----Original Message-----
From: Dave Voorhis
Sent: Saturday, December 07, 2019 9:45 AM
Subject: Re: [TekScopes] 577 D1 function won't turn off

It is a used CRT that the previous owner was told was extracted from a working unit, though “working” may or may not have included storage. The previous owner of my 577 didn’t know.

And that’s the reason for my question — before I (eventually) launch into storage calibration, I want to know whether or not it’s reasonable for the storage calibration settings that work for one CRT not to work for another. If it's typical for D1 CRTs to be interchangeable and the storage to essentially work — though perhaps not optimally — I’ll keep my eye out for another replacement.

Instead, if it’s typical (or at least reasonable) for changing the CRT to result in non-storage condition then I'll only look for a replacement CRT once I confirm it’s defective, if it is. ‘Erase’ does appropriately “green" the screen so I presume at least the flood guns are working.

On 7 Dec 2019, at 17:34, Dennis Tillman W7PF <@Dennis_Tillman_W7PF> wrote:

Hi Dave,
Was the replacement CRT a new CRT? If not new how do you know it was any good in the first place?
Dennis Tillman W7PF

<SNIP>
-----Original Message-----
From: Dave Voorhis
Sent: Saturday, December 07, 2019 4:47 AM
Subject: Re: [TekScopes] 577 D1 function won't turn off

I have a 577 D1 that came with the original but weak CRT installed and a replacement CRT in a box. Storage mode on the original weak CRT worked well, but the primary trace was almost too dim to see.



--
Dennis Tillman W7PF
TekScopes Moderator

Siggi
 

On Sat, Dec 7, 2019 at 1:16 AM Dennis Tillman W7PF <@Dennis_Tillman_W7PF>
wrote:

The other one is the storage Brightness knob doesn't seem to do anything.
On my new-to-me 577 the storage brightness knob only works when the
collector supply is turned down as near zero as makes no difference.

Dave Voorhis
 

Thanks for the tips, and I will try the storage calibration when I get a moment.

Incidentally, I also have some analog storage Tek scopes — a 549, a 7623, and a 564.

The 549 is in excellent condition and works well including most of the storage capability. I say “most” because the enhanced mode has stopped enhancing. I’ll have to look at that when I get a moment. The CRT seems a tad dim but entirely usable. I haven’t investigated whether the dimness is due to a worn CRT, a bias or Z-axis issue, inherent in the design, or some/all of these together.

The 7623 is usable but in need of general cleaning and fettling, though the storage facility works. Storage mode is rather low-contrast — apparently a characteristic of its design — but works well and the variable persistence is very useful.

The 564 is unrestored and has various issues, and the storage facility clearly needs adjustment but works (-ish) once it’s warmed up.

None appear to have the storage target burn-in that’s apparently characteristic of all of these, so I guess I’m fortunate in that respect.

I also have two digital storage ’scopes — a 7D20 in a 7603 mainframe that’s currently down due to power supply issues, and a 222 portable that works and looks like new though the original lead-acid battery is kaput.

So much to work on, when time permits. :-)

On 7 Dec 2019, at 18:51, Dennis Tillman W7PF <@Dennis_Tillman_W7PF> wrote:

Hi Dave,
I have probably used at least fifty Tek scopes in my lifetime but fewer than five storage scopes or curve tracers. The first time I tried using storage was on an almost new 549 in 1968. I remember thinking to myself that storage was better than nothing at all but it wasn't all I hoped for. Two things contributed to that impression: The stored traces would bloom, and the storage was hard to control. In the years since then I have learned to settle for what I get on Tek storage scopes instead of being pleased with the results.

I use my 577-D1 a lot and I frequently need to store the results. At one point I got annoyed with the results and decided that calibrating the storage circuitry according to the manual could only improve things. Since this was the first time I ever adjusted a storage scope I cannot say whether the directions were confusing to follow or whether I found them confusing. I was also surprised that many of the adjustment steps seemed to interact with each other or seemed to do nothing at all. After doing the best I could to follow the written directions it was hard to tell that I had made much difference at all. At that point I just ignored the directions as I tried adjusting the pots for what I thought was the best result.

Looking back there are several possible explanations for why I wasn't able to improve my 577-D1 as much as I had hoped.
1) I have limited experience with storage technology.
2) I don't understand the limitations of storage technology.
3) My expectations for storage are unrealistic.
4) I did not understand the calibration procedure.
5) I have a problem following directions (a recurring issue in my life).
6) The particular CRT I was trying to adjust was getting old or worn out.

I do know enough about storage that it is important to go through the cal procedure when you change the CRT. The cal procedure shouldn't take you as much time as it took to change the CRT. It may provide answers to at least some of the things I listed above. I'm starting to think that if I can find the time it would be worth recalibrating my 577-D1 storage again.

Dennis Tillman W7PF

-----Original Message-----
From: Dave Voorhis
Sent: Saturday, December 07, 2019 9:45 AM
Subject: Re: [TekScopes] 577 D1 function won't turn off

It is a used CRT that the previous owner was told was extracted from a working unit, though “working” may or may not have included storage. The previous owner of my 577 didn’t know.

And that’s the reason for my question — before I (eventually) launch into storage calibration, I want to know whether or not it’s reasonable for the storage calibration settings that work for one CRT not to work for another. If it's typical for D1 CRTs to be interchangeable and the storage to essentially work — though perhaps not optimally — I’ll keep my eye out for another replacement.

Instead, if it’s typical (or at least reasonable) for changing the CRT to result in non-storage condition then I'll only look for a replacement CRT once I confirm it’s defective, if it is. ‘Erase’ does appropriately “green" the screen so I presume at least the flood guns are working.

On 7 Dec 2019, at 17:34, Dennis Tillman W7PF <@Dennis_Tillman_W7PF> wrote:

Hi Dave,
Was the replacement CRT a new CRT? If not new how do you know it was any good in the first place?
Dennis Tillman W7PF

<SNIP>
-----Original Message-----
From: Dave Voorhis
Sent: Saturday, December 07, 2019 4:47 AM
Subject: Re: [TekScopes] 577 D1 function won't turn off

I have a 577 D1 that came with the original but weak CRT installed and a replacement CRT in a box. Storage mode on the original weak CRT worked well, but the primary trace was almost too dim to see.



--
Dennis Tillman W7PF
TekScopes Moderator


DW
 

I have an update

I performed the 370V calibration on TP 2 to ground from the D1 storage board. I was about 365 so i put it right at 370

I took pictures of the adjustments on the D1 board and very carefully moved each one slightly back and forth and noted the display.

I fixed my problem by carefully turning down SENS COR from the 3 o'clock position to near the 12 o'clock position, the ghosting problem disappeared and the D1 storage appears to work correctly and turn off when I don't want it. I turned off the instrument and back on, a brief flash of the screen but the display came on free of storage display artifacts

All the other settings are default except 370V and SENS COR

Hopefully this might help anyone out by trying this, maybe reply with your results to see if this is my particular case or perhaps it is a fix hopefully for some people

DW
 

I would like to make a correction it is NON storr that I adjusted not SENS COR

It is on the D1 storage board you will notice 4 blue dials grouped closely together, the second one over to the right, NON STORE is what resolved my problem

Mlynch001
 

Great information. Thanks for the update.
--
Michael Lynch
Dardanelle, AR