Tek 11301 focus - Page 1
Forum section: electronics / repair

author: cncjerry
author_rank: Unknown
timestamp: June 09, 2017, 08:28:09 pm
content: As Dr. Kraus in Hellboy would say, "you need to stay Fock-used".A friend gave me an 11301A, I believe, as it has the touchscreen, etc. Only issue I know of is that the focus is off. There is a switch on the front that allows you to focus both the horizontal (left dial, I assume, no manuals) and the right dial does focus the vertical. The left dial for the horizontal focus has little or no impact on the focus. Any ideas? I can't find the service manual for this beast after about an hour with google. There is a reference manual that is downloadable but it is very thin. Maybe I am looking at the wrong product numbers?The vertical focus has a wide range whereas the horizontal has not so much range of change. The tube seems bright, and the characters seem to be positioned correctly as wells as the touch screen locations. Just the horizontal focus adjustment and I think it would be off and running. Not that I need it, just sort of interesting scope.Any ideas as to where the manual might be hidden or if there is an internal horizontal focus adjustment limiter would be appreciated.ThanksJerry

author: cncjerry
author_rank: Unknown
timestamp: June 11, 2017, 06:49:34 pm
content: I found a manual for an 11302a which looks close to the 11301. Still can't find schematics. I plan to take out the CRT boards and check the caps for the heck of it. Otherwise this is a long short due to the lack of manuals.

author: cncjerry
author_rank: Unknown
timestamp: June 12, 2017, 12:32:34 am
content: Well, having not found doc or schematics, and finding about 10 pots on the two or three CRT driver boards, and having nothing to lose, I started tweaking and low and behold, I have a workable display.I have't used an analog scope in a while so at first I thought the trace was still out of focus but after playing around with it and comparing the trace to my tek DSO digital phosphor in envelope mode, I found the trace thickness in the two scopes to be "identical" (cousin Vinnie). I used the cursors on the two scopes to measure the trace and they both were about 10us when viewing a 1khz signal.The one thing I still like an analog scope for is displaying modulation patterns (AM, SSB). Though I can get a decent display using a DSO, it takes a fair amount of screwing around.This 11301 is actually pretty cool now that I have it working. It has an externally referenced counter, touchscreen, 1, 2, and 4 channel amps up to 400Mhz, all types of measurements, etc. I doubt I'll ever use it for anything productive seeing that I look at modulation about once a year but at least I can say I rescued it from the dumpster.If anyone does have the service manual please let me know. Schematics would be best. I think there is software available for the calibration. Though I was able to tweak it into near perfection, there must be still something wrong with it as the horizontal focus adjustment range is nowhere near the range of the vertical.

author: Johnny10
author_rank: Frequent Contributor
timestamp: June 17, 2017, 06:36:35 pm
content: Great Scope Jerry !

author: cncjerry
author_rank: Unknown
timestamp: July 20, 2017, 08:55:32 pm
content: I've come to realize that the wide trace above is an issue. I played around with the display adjustments and they don't impact the trace at all. From what I can tell in the service manual, there is at least one DAC that controls the trace voltages and as part of the calibration, these are all adjusted automatically.When I power on the unit, I get a solid Scope Logic board error. Again as far as I can tell from the limited information in the service manual (no schematics) one of the issues that can cause this error (or a correction) would be to reload the calibration data. I now suspect that the calibration EPROM could be bad. The battery voltage is ok so unless someone swapped the battery and lost the calibration, I was thinking I would replace the EPROM but I can't find one in the area where the battery is located.Anyone have any experience repairing one of these scopes? I would like to have a 400Mhz or better analog scope on hand as I use them to check modulation and though my digital scopes can do it, the analog scopes are easier. I also have a bunch of spectrum analyzers so this is a weak argument, but if I can fix this beast I would prefer to do it instead of pitching it.Thoughts? What should I look for in an EPROM? Tek part number?Jerry

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: July 21, 2017, 12:24:10 am
content: No idea, have you tried the Yahoo Tekscopes forums?https://groups.yahoo.com/neo/groups/TekScopes/conversations/messagesYou need to register

author: cncjerry
author_rank: Unknown
timestamp: July 21, 2017, 04:12:09 am
content: yes, I posted up on tekscopes twice since I received the scope. it's no big deal as the plug-ins are in great shape and I am able to use them in a DSA602 that I have. I would like to have the 11301 working though, instead of just scavenging it for cables and connectors. It's a shame that this scope doesn't have the following as other models as it has quite a list of features.I'm going to run the calibration software and see if it holds the cal constants. If not, maybe someone will want if for parts.Thanks for the input.Jerry

author: WastelandTek
author_rank: Frequent Contributor
timestamp: July 21, 2017, 04:28:02 am
content: you got RF going in the shack Jerry? That can leak in and widen the trace.

author: voltz
author_rank: Frequent Contributor
timestamp: July 21, 2017, 09:17:25 am
content: It doesn't look like a focus problem to me as the characters are sharp and the verticals are too. Its as if there is some FM on the generated signal (maybe 50/60Hz? mains hum). Can you confirm the problem is still there using a different signal source. Rule that out as the problem before diving in.

author: alm
author_rank: Super Contributor
timestamp: July 21, 2017, 10:46:12 am
content: Are the power rails clean? Noise from the power rails could very well couple into the signal path.

author: cncjerry
author_rank: Unknown
timestamp: July 21, 2017, 03:08:48 pm
content: All good points above and I will go back and look for RF but this scope is a little different. Let me see if I can give you more scope below.1) Sprinkled around the scope are about 10 - 15 pots that impact the horizontal and vertical positioning as well as the focus of the characters in the display. The horizontal and vertical pots impact the trace but focus has no impact on the trace, just the characters. You can tweak the focus of the corners, sides, rotation, astig, etc but nothing changes the trace width with the exception the brightness of the overall display.2) The scope has a high accuracy mode that looks like it moves small lines within the graticule boxes in order to improve the accuracy of the horizontal and vertical trace. The scope must be able to see these lines somehow, maybe through the infrared touch screen? No idea how. Now that the trace is so wide, it fails the enhanced accuracy setup.3) There is a display adjustment button that enables you to set the astig and max brightness for the characters and main trace as well as the delayed and XY modes. There is also a dial with a button next to it to enable you to set the brightness for the characters more dynamically instead of having to go into the display adjustment mode. I usually would keep it in the main trace as it helps to adjust the brightness depending on how many waveforms are on the display - more waveforms require the brightness to be brought up. At one point, I had the trace pretty narrow but the lower I went in frequency, the wider the trace became. Adjusting the brightness made the trace narrower so somehow the scope must change the trace focus based on brightness. Go figure, to much automation if you ask me.4) In the service manual they teach about using calibration software, which I have but it runs on old dos, to set the trace calibration. I believe the issue with the trace is related to DAC voltages not being correctly stored and read from EPROM. I think all the voltages for focus and brightness related to the trace (for each horizontal setting) are stored and adjusted by DACs instead of pots like the character displays. This is what I need help with, finding the EPROM that stores these calibration constants, possibly replacing it, and then rerunning the calibration which I think is pretty much automatic.This scope is huge, has tons of functions for an old scope, all discrete logic with a few micros. I don't know how it reads the trace and calibrates it but somehow I think it does. When you run the enhanced accuracy mode, it puts small lines up on the screen within specific graticule squares so it must be reading them back somehow. It also seems like it has a set and forget (with the pots) for the characters and some kind of dynamic adjustment for focus and brightness of the trace.Let's see if this jogs some thoughts.ThanksJerry

author: cncjerry
author_rank: Unknown
timestamp: July 21, 2017, 03:18:39 pm
content: By the way, it happens with all trace sources. Also, when I was able to tweak the brightness to get a near perfect trace for 10Mhz signal, when I would raise the horizontal timebase down to put more waveforms on the screen (longer time per graticule), the trace would start to widen again. If I brought the brightness up I could make it narrow until I had about 8 waveforms on the screen and then I would run out of brightness. If I then started with one 100Khz sine wave on the screen, it would be wide and raising the horizontal timebase would again make it wider.It's tough to explain and took me hours to get a decent trace out of a 10Mhz signal so my next step is to find the EPROM, replace it, setup a dos box and run the calibration software.One other thing, the service manual lists about 10 voltages to check, half of them in the 1,000 - 2,000V range and it teaches that the actual value of the voltage at this specific connector varies by the DAC output depending on brightness, horizontal settings, etc. so again, this leads me to think the scope automatically sets the brightness and focus depending on the signal and timebase. Another interesting point is when I moved the horizontal size (they call it size instead of timebase) I could see the trace start out in a correct, thin trace, and then snap wide like it thought it should adjust it.

author: cncjerry
author_rank: Unknown
timestamp: July 21, 2017, 05:20:05 pm
content: one last post on this one, it looks like all the negative high voltages are incorrect. I don't understand how this could be because one in particular varies with the astigmatism which works, but the pin reads +2.6v instead of -100 or so. According to the service manual these should be referenced to ground, which I did, so this is weird. All the negative high voltages that I can read up to -1000v are zero. According to the manual, this could be the DAC or the scope logic board or the negative regulator, which is the most likely culprit, but since there are no schematics available, I think this one is going to set for a while.The major bummer on this one is I dropped my Surface Pro 3 onto the cement floor while reading the voltages and now the screen is toast. This is a big heartbreak as I have everything on that device.So there you go, one free scope that doesn't work wins out over a $1,900 Surface Pro 3.And tomorrow is my birthday, what a present!

author: cncjerry
author_rank: Unknown
timestamp: July 24, 2017, 02:55:36 am
content: OK, now it is bothering me...Having eaten my Surface Pro 3, I decided to try the calibration software. It took me a while to get a computer to boot native DOS and then I expected to have RS232 cabling problems, but the scope connected to the computer using the first 9Pin to 25Pin cable I tried. The software read the scope serial number and software version and then barfed. The Tek adjustment software I have is version 2.19 which handles 11301 - 11302A software versions from 2.0 to 3.0, not my 3.1.Anyone have the 11000 series software greater than version 2.19?I know this is hopeless as in order to do the checks and adjustments you need plug-in signal standardizers as well as Tek NTSC and PAL Video generators (why both I don't know) along with a ton of other specialized equipment.I might pull this thing apart and see if I can trace the negative high voltages (or is that negative extra low voltages?) Using a DAC it somehow sets voltages down to -2,000. Right now I am reading most of them down around zero.Someone once posted about staying away from the 11000 series and I agree. My DSA602 works perfectly and is a pretty interesting beast but this 11301 isn't very friendly. I have around 10 scopes so I don't need it, just would like to see it in working order.ThanksJerry

author: andy2000
author_rank: Frequent Contributor
timestamp: July 24, 2017, 04:30:02 pm
content: If the voltages are really that far off, I'm surprised you're even getting a trace.

author: WastelandTek
author_rank: Frequent Contributor
timestamp: July 24, 2017, 04:49:18 pm
content: Quote from: andy2000 on July 24, 2017, 04:30:02 pmyeah, something's funky

author: alm
author_rank: Super Contributor
timestamp: July 24, 2017, 05:00:33 pm
content: Are all voltages referenced to the same ground and are you measuring relative to that ground?

author: cncjerry
author_rank: Unknown
timestamp: July 24, 2017, 06:17:25 pm
content: I agree on the voltages. If the negative voltages were that far off, and one in particular is driven by the astig front panel command and that does impact the astig, then I would think the trace would be N/F. The characters are all pretty crisp until the scope initializes and then I have to reset the brightness. The doc says all voltages are referenced to ground. I went back over them again trying other grounds. I haven't put a scope on them as the doc says to use a meter. I must be doing something wrong as they can't be that far off. I found other voltages on the board like +/- 5, +/- 15, +/- 50 and they are report the correct voltage to the ground I am using. I checked the connector label a few times but that could be a mistake. I am trying to be careful as some of the voltages are as low as -2,000 and I don't have a high voltage meter or probe.I am making progress with the software - at least it loads, initializes the scope, reads the serial number, but it won't run the routines as it reports that it can't find the EIS RCS number. On a status screen it reports the same for the RCS number, whatever that is, that it is unknown. I looked at the four files on the diskette for the 4 models supported (e.g. 11301, 11301a, 11302, 11302a) and the files are all the same. So I tried changing one to match the 11301 with version 3.1 of the software - same problem.On tekscopes a person reported that the version of the software I have is the latest and to ignore the 3.1 version error I get at load but no other hints.I'm still playing with it. Worst case is I just throw it away and use the plugins in my DSA602. It has a lot of cables that will be handy but I'm not ready to pitch it yet.ThanksI don't know if I am going to be able to make much progress unless I get the diagnostics and calibration code to run.

author: WKibler
author_rank: Contributor
timestamp: April 05, 2019, 04:45:19 am
content: Sorry about the extremely late reply. I encountered the same error. "EIS RCS number". What fixed it for me was to run the software in the root of the drive in the TEKCATS folder. I had been running it from a folder on my desktop and it the error seemed to me like there was a file it could not find. I moved the folder to the root of the drive and the error went away and I was presented with a list of tests to run. If this doesn't fix it for you it may be that some .eis files may be missing from your install. Let me know and i can send you what I have.I have an 11301 and a 2440, both I have refurbished/re-capped etc etc. The 11301 is a solid scope which I intend to create an app-arduino bridge to bring out some controls to an iPad. I know, I'm nuts. Wish me luck.