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Hi all.

Apart from the CEN-U45 is there a readily available replacement?

Some people are using TIP 102's with the legs crossed over...


Any other suggestions?

Thanks in advance.


James

I'd say it's most likely a bad solder joint or broken part - something in series with the signal path such that it goes open, but still has some capacitance to couple an attenuated version of the signal. A short of signal to ground can act that way too, say from a shield braid strand, solder glob, or loose piece of hardware or wire clipping, but I think it's less likely than an opening scenario. It doesn't necessarily have to be right in the signal path - a bad connection in a circuit upsetting operation can do it too. I think you're getting very close, at least location-wise. Your descriptions have jogged my memory a little. I believe the "IF select section" you mentioned routs everything ultimately to the single 110 MHz IF out. I assume the "2072 MHz 2nd converter IF output" you mentioned is its version of the 110 MHz IF. The 829 and 719 MHz stuff does not participate in the low band operation, but apparently the 110 MHz IF stuff is built into the same module. Right?

I don't recall the RF deck construction, but I remember everything is jammed in tightly. I hope you can get enough access to figure it out without too much grief. Good luck.

Ed

I seen your repository a while ago and was thoroughly impressed, though this was before I had the tapes or a terminal. I'll have to check it out further. Thanks for reminding me about it. Also thanks for the link to the 4041, I sent an inquiry.

On the belts, I've seen people 3d printing tape belts for other kinds of tape players with flexible TPU filament. Which is pretty cool, probably will take quite a bit of testing with different durometers/lengths/widths. If all else fails, this is definitely an option to look into.

From what I've read the 4200s are upgraded and rebadged 4100 terminals. The only real difference is a higher resolution and more performance. The 4200s have modified internals that integrated a bunch of logic into asics on a single board and some have larger memory. 4200's are fully compliant with 4100 stuff, so it's likely I can use the ATOM/EZ-TEST, I'll definitely have to try it if I can acquire that 4041. The terminal I have access to is a 9201T which is just a rebadged 4205 that was dedicated to be used with the DAS9200, although I don't have a keyboard for it, which is problematic. Maybe it's possible to take inspiration from your keyboard interface and build a kind of emulated keyboard for Tek terminals, as i'm sure that would be useful for others. Seems like the terminal keyboards are more rare than the terminals themselves, which is unsurprising.

I originally got the tapes, because I figured I could use the EZ-TEST tapes to bypass having the EZ-TEST PC software, which is basically non-existent at this point. The 4200 Mod tapes I've been told are largely the same as the non-4200 Mod EZ-TEST tapes but have DAS9200 support among other machines. They claimed the mod tapes have the DAS9200's Tek Codes and Standards for the 8150 Test System Interface but couldn't confirm it and might have been misremembering. I know the EZ-TEST tapes you have backed up have DAS9100 support, but unfortunately no DAS9200 support. So it's very possible these mod tapes have what I'm looking for. The TSI 8150 codes/standards are really what I need from the tapes, as it's possible to talk with any TSI 8150 capable Tek machine provided you have the TSI 8150 codes/standards without using any EZ-TEST at all, and likely is the most future proofed option.

Thanks for the reply!

I have 3 CRT's that came with a lot that I acquired 2 154-0910-00 for a 492 Spectrum Analyzer and 1 154-0934-00 for a 494 can anyone use one or all? I don’t have either of those analyzers so if one of you have one of them here's your chance to score a CRT. The 2 910 are in the original cardboard holder all with Tektronix tags indicating part number. They look new but actual condition is unknown.

Let me know if you want one!

Mark
W7HPW

Real Radios Glow in the Dark

ALLRIGHT!!!
DMM selector switch removed successfully, TEK switch module replacement due in this weekend.
Took me about two hours. I thought it would take days. I will post some pix later.
However, the reason for this is a new toy, the Yihua 948 desoldering station. The tool is a gun with a heated tip (temp controlled) with a hole in it. There is a continuous suction pump in the base unit actuated by a trigger. Just put the tip over (and around) the switch pin, rock it around a bit to insure melting and pull the trigger. Does a really nice job.
I needed to desolder 40 pins to remove the switch assembly as a unit. I had to re-work about 6. after that the switch assembly just fell out. Board is very clean, no smutch like with solder wick. MUCH better than a Solder-pullit. I wish I had discovered this years ago. I am really impressed.
I expect the rest of the repair to go smoothly. Still want to resolve the Readout ring not recognizing the 11K pin on the 10X probe though...

It seems that the color rules are:
1. Avoid blue plastics used by Tek
2. Avoid red M&Ms

Neither of them last 40 years!

I recovered and posted the files for EZ-TEST v5.0 and the 4041 System Verification tape on my 4041 github repository 5 years ago:

I haven't used my 4041 since then - so I don't know if it is still working.

Biggest issue with making any kind of backup tape is the DC100 tape drive belts are moldy and broken - even the new-old-stock tapes in shrink wrap.

Same thing goes for my precious 1979 Tektronix 4052 and 4054A computer DC300 tapes.

I created a 4041 "Console Commander" using a tiny M5STACK ATOM LITE ESP32 PICO CPU module with an ATOM MATE where I soldered in a 3.3V to 5V level shifter to interface to the 4041 keyboard interface and posted the files in this repository - to use the programming keyboard interface to load programs into my 4041.

I would bet you could load the EZ-TEST programs onto the ATOM instead of my ADVENTURE program.

I don't see any mention of the Tek 4200 terminals in the 4041 Graphics ROM manual. If the 4200 terminal can emulate the 4000 or 4100 terminals, then it may work.

A quick google search for "Tektronix 4041 buy" turned up this link:

I have these 5 tapes for the 4041, any chance someone has a working 4041 still and can back them up? If they aren't dead that is. I'd be willing to pay for shipping both ways and for your time.

4041 DDU Checkout Software Version 1.1 4041 System Verification RLSE # 2.8 S45F010 opt.04 TEK-EZ TEST Vol.I-Generator 4200 Mod DNS Version 5.1 (DNS0012) S45F010 opt.04 TEK-EZ TEST Vol.II-Translator 4200 Mod DNS Version 5.1 (DNS0012) Likely a blank tape, (but still would like to see if it has data and back it up if it does)

I really need the TEK-EZ TEST Vol.I/Vol.II 4200 Mod tapes specifically for my DAS 9200 / 4200 series TEK terminal and have been looking for a 4041 for a long time but never seen one for sale yet.

Hello everyone,
My name is Jack, and I have a 575 that I am trying to understand better, and to calibrate and fix a couple of small things. The present issue is that I can’t get the single family switch on the step generator to do anything. The repetitive position works as it should, but switching to single family makes all curves displayed on repetitive, disappear.
I have the instruction manual for the instrument, and the schematics for all the different blocks. I have cleaned the switch contacts, but am at a loss.
Any suggestions for me would be greatly appreciated. I have very limited diagnostic capabilities.
Very sincerely,
Jack

The cam switch drum is one of the many plastic parts in the 7000 and 500 series with this issue. The material becomes brittle and develops chalky white residue on the surface. From what I gather, the problematic plastic is delrin or acetal resin.

One of the reasons I divested myself from this series. The intricate plastic parts break left and right, and when they do, you have quite a problem on your hands.

Karin,

There was a request by another list member for help acquiring pages that
are missing from the various 7934 PDF copies of the May 1986 revision
manual out on the internet. I was trying to figure out how closely the 7934
manual, revision May 1986, found on the TekWiki site, matches an actual,
original 7934 manual as published by Tektronix. So far, it is clear that
pages 3-1, 6-22 and 6-23 are missing from the PDF copy on the TekWiki site.
In addition, the copy on the TekWiki site has many pages that appear to be
partial scans of larger pages.

It would be useful, if tedious, for someone who owns an original copy of
the May 1986 manual to do a page-by-page comparison to see what other
differences exist between an original manual and the copy on TekWiki.

I have a 7934 and an original 7934 manual published by Tektronix, revision
May 1996, *revised August 1987*, from which I have scanned the above listed
three missing pages and added them to my local copy of the May 1986
revision. I may decide to replace the PDF copy on TekWiki with my updated
copy. The pages between the two revisions appear to be consistent.

I am also in the process of scanning my August 1987 revision which I will
also put on the TekWiki site, but that will take some time because of the
large number of foldout pages. You probably know how that goes.

My intent has been to provide an accurate copy of *a* 7934 manual for
others to access.

DaveD
KC0WJN
Mims, FL


On Tue, Mar 25, 2025 at 19:15 Karin Johnson via groups.io <karinann=
[email protected]> wrote:

I have an original Tektronix service manual for the 7934, dated First
printing May 1986, I also have two, count them two, 7934.
Is there any question I may answer for you?????

Karin Anne Johnson P.E. K3UU
Palm Harbor, Florida

Just as a sidebar, my manual in section 7, last page is 7-74.

Karin

I had problems with broken individual cams and bushings in the attenuator of a 7A29, which I think are the same gray plastic. I had to do some tricky repairs to put them all back together. The story starts here and there are some nice pictures associated:

/g/TekScopes/message/206747

In my case, the cams did not wear down or anything like that - they just broke open from around the shafts. The plastic was still shiny and had good surface, but simply cracked apart I think due to being too flimsy to take the stresses - those should have been stouter or of a stronger material. I also think the too-radical lift in the cam and follower design and lack of lubrication aggravated the situation, as described in the discussion and picture captions. OTOH, I also noted that the bushings are low stress items yet cracked anyway, so there's an aging/chemical deterioration issue too.

Ed

I have an original Tektronix service manual for the 7934, dated First printing May 1986, I also have two, count them two, 7934.
Is there any question I may answer for you?????

Karin Anne Johnson P.E. K3UU
Palm Harbor, Florida

Look under "Surface Delamination."

Greg

Hi Wamor,

Would this work on a TDS620A?

Rafael

To me, that appears like someone has used an incompatible contact cleaner or such on it.

Russ

I would very much appreciate those scans

Mark
W7HPW

Real Radios Glow in the Dark

On Sat, Mar 22, 2025 at 07:39 AM, Dave Daniel wrote:

I have sent pp. 31, 6-22 and 6-23 to Mark, the OP.

Where and who is "Mark, the OP"? Could you consider uploading just those 3 pages, 3-1, 6-22 and 6-23 to TEKSCOPES files area? That would help anyone, including me, update the old manual until such time as Mark can insert those pages into that copy, where ever that is? Then I don't have to remember to update or download a newer copy at some time in the future.
Thanks so much for taking the time to do this,
Bill

On Mon, Mar 24, 2025 at 04:17 AM, Sigur?ur ?sgeirsson wrote:

I've never seen such a thing (/g/TekScopes/album?id=301415),
how strange. I wonder if anyone here knows what sort of plastic Tek used
for these?

I have some (PG506 for one, IIRC) cam switches that are cracked on the ends, and I expect they're on borrowed time. Nothing as bad as in Clark's photos, though.

I've never looked closely at one of those drums, but it looks to me that it
would be relatively straightforward to 3D print a replacement nowadays.

I've had the same thought, more recently with 7A29 cam lobes. Those are a slightly different beast, but suffer severely from cracking (and I have one that's missing entirely).

Thinking about this for the more typical long cam drums, I suspect one could convert the dotted alignment diagrams in the service manual to a table, and produce cam rings for an individual contact using a given column of on/off sequences for a given contact to generate the lobes (assuming equal intervals?) on a given drum diameter. I think this would be straightforward in OpenSCAD, but have never looked closely at the ramp geometry. Stacking those rings would give you the full cam drum, and then there'd be a mildly annoying detent gear and/or bearing section at the ends, plus grooves for circlips. I suspect that would be tedious, unless it could be parameterized somehow.

All purely academic speculation, as my free time is about to go towards outdoor chores instead of playing with the 3D printer.

Adam