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On Sun, Sep 13, 2020 at 09:40 PM, Egge Siert wrote:

I assume Kurt, like me, also roams the internet looking for interesting items
and their pictures.

Hi Egge Siert,
I saw Kurt was mentioned as the author of the pictures but there's still quite a gap - geographically as well...

Raymond

On 9/13/2020 2:39 PM, n4buq wrote:

Harrison,

With F558 blown (or removed), what kind of resistance from the junction of F558/L558 and ground do you see? Yes, it's a very basic question, but I'm wondering if something is being overlooked (e.g. C558 shorted, etc.).

If you have a variable, current-regulated power supply capable of producing approximately 32VDC and setting the current limit to around 0.25a, it would be interesting to observe the current as the voltage is slowly increased. In other words, perhaps it doesn't draw excessive current until it reaches a certain "knee" voltage. If it draws excessive current at, say, 1V, then that might indicate something's a dead short but if it draws nominal current up to, say, 20V, etc., then it might be easier to find what component(s) are suddenly drawing that current. It would also be good to watch the test points to see what their waveforms show at the various test points (TP 57 through TP 60) to see what those are doing at voltages that do not produce excessive current.

I know there are probably much better ways to troubleshoot this so hopefully someone will suggest better ways.

Also, as I recall, U550 is not too difficult to desolder (small pins that solder-suck pretty easily) and it wouldn't be too hard to eliminate that from the circuit and see if that stops the excessive current demand.

Good luck with it. I wish I had better suggestions to offer.

Thanks,
Barry - N4BUQ

----- Original Message -----

From: "Harrison" <buma7@...>
To: [email protected]
Sent: Saturday, September 12, 2020 10:10:40 PM
Subject: Re: [TekScopes] Tek 4654M; No Trace, No +5V, No +95V; Help

Thanks for the tip Barry. Unfortunately Sphere doesn't have any U550s at
this time.
I may be off track or have confirmed that my issue is with the U550 module.
Currently I have the 32V, +5V and -5V banks up. The 95V bank still reads
about 7.0V. Fuse F558 blows upon powering up the 465M Scope. I.E. when the
power button is pull to on.
My latest effort was to remove the 95V jumper and lifting one lead of R541.
After which I put a new 0.5A fuse in the F558 holder (It calls for a 0.25A
fuse, which I currently don't have any so I thought I'd be safe enough with
a 0.5A fuse). Anyway with the jumper removed and a lead of R541 raised,
powering up the unit resulted in the F558 fuse blowing immediately.
Contemplating where to go from here.
Harrison N1FAM

Once again. the 2.0 and 2.2 caps in the +95v supply are well known to be leaky.

I have had this happen on four!! different 465Ms.

They will seem OK at lower voltages.

? -- Bert

I would certainly be interested in seeing a scanned copy of this waveform
pamphlet. I learn something new every day.
Gary

The first 10 pages of 20 are here:



There were a couple of minor glitches in the Photoshop artwork, already fixed for the final version; which will be later next week.

As expected, this is a real time-burn so I have to get back to some real-world work, tomorrow's a school day after all.

Best,
Bill

Hi Raymond,

I assume Kurt, like me, also roams the internet looking for interesting items and their pictures.

Greetings,

Egge Siert

I would certainly be interested in seeing a scanned copy of this waveform
pamphlet. I learn something new every day.

Gary

--
Gary Robert Bosworth
grbosworth@...
Tel: 310-317-2247

Harrison,

With F558 blown (or removed), what kind of resistance from the junction of F558/L558 and ground do you see? Yes, it's a very basic question, but I'm wondering if something is being overlooked (e.g. C558 shorted, etc.).

If you have a variable, current-regulated power supply capable of producing approximately 32VDC and setting the current limit to around 0.25a, it would be interesting to observe the current as the voltage is slowly increased. In other words, perhaps it doesn't draw excessive current until it reaches a certain "knee" voltage. If it draws excessive current at, say, 1V, then that might indicate something's a dead short but if it draws nominal current up to, say, 20V, etc., then it might be easier to find what component(s) are suddenly drawing that current. It would also be good to watch the test points to see what their waveforms show at the various test points (TP 57 through TP 60) to see what those are doing at voltages that do not produce excessive current.

I know there are probably much better ways to troubleshoot this so hopefully someone will suggest better ways.

Also, as I recall, U550 is not too difficult to desolder (small pins that solder-suck pretty easily) and it wouldn't be too hard to eliminate that from the circuit and see if that stops the excessive current demand.

Good luck with it. I wish I had better suggestions to offer.

Thanks,
Barry - N4BUQ

I think I've found the problem. I disconnected the voltage multiplier (A1U850) from the HV traansformer (A1T800) and attached a NE-2 lamp to the transformer output through a 100Mohm resistor, and powered the HV section from a bench supply set to current limit at the fuse rating. The neon lamp glowed just fine. I reconnected the voltage multiplier and tried again and the bench supply went into current limit immediately. So I disconnected the voltage multiplier, and tried again. The neon lamp glowed. I repeated this several times just to be sure. Feeling encouraged (and really brave), I disconnected the bench supply and put a fuse in the holder and powered it entirely from the TM506. The lamp glowed again.
Finding one of those voltage multipliers seems impossible, and the prices I've seen are crazy high. Generic multipliers from old TV sets are just way too big to fit. So I've ordered a bunch of 5KV diodes and capacitors and will try my hand at rolling my own voltage multiplier (or arc generator).

I would like to know what the CRT filament voltage is supposed to be. I haven't found that in my manual.

Triggered by Walter Shawlee's recent topic about his R5030:

A while ago I noticed that all but a few external photos in Tekwiki's 5030 article show my 5030, that very sample. Does anybody happen to know anything about its history? It must have been a Tekscope member's property once...

Raymond

On Sun, Sep 13, 2020 at 05:55 PM, Raymond Domp Frank wrote:

Doesn't it work the same as the 576, IOW remove the CRT bezel and pull out the
readout module from its edge connector at the back?

Have a look at the manual of the R5031 on TekWiki. The R5031 is the bistable storage rackmount version of the 5030. Its manual is available there. The readout is mounted the same as in the 576, like I thought.

Raymond

On Sat, Sep 12, 2020 at 11:00 PM, walter shawlee wrote:

In addition, the front fiber optic scale display has many burned out and dim
segments, but I can't see how to get in there to change lamps. again, advice
please! How the heck does that assembly come out?

Doesn't it work the same as the 576, IOW remove the CRT bezel and pull out the readout module from its edge connector at the back?

Raymond

Hi Walter,

Thank you for the information, and that exposed crystal certainly sounds like a reasonable explanation for the low spec frequency adjustment called for in the cal procedure with the case removed. Definitively would concur Tek might have made that adjustment accessible from the outside, ideally with a hole near the external 10MHz input jack would have made a lot of sense. Also guess the design budget for this model back then did not allow for a TCXO / OCXO, as these where probably more expensive back then? Nowadays one could get off ebay a decent TCXO from the US for under $20. I really haven't looked at the circuit, but perhaps as a viable upgrade one could think about building in either type of stabilized crystal oscillator hooking it up into the external 10MHz input, or if possible right into the circuit to retain the external input functionality.

Matter of fact just remembered that I do have two 10MHz TCXO's in my junk drawers, taken from old scrapped GPS receiver boards. One is labeled "RAKON TX0408R 10.000MHz", but has no external trim adjustment. Also have one this is physically larger and does have an adjustment. This last one is marked "GH-1711 10000.00KHz TOKYO DENPA CO. LTD" (now part of Murata). Could unfortunately not find any data on either of these, anyone familiar with them?

In any case to Tek's credit I have to say that as-is the Counter/Timer functions have been quite stable and very useful for the time I have owned this scope, except of course for that very small 70Hz long term drift which after 30 odd years would be perfectly acceptable as an age related issue. I like this scope very much and use it quite a bit more than others, including my 2465B, due mainly to all the versatile counter/time/voltmeter/cursor functions.

Thanks again.
-Alex

My room was the single room on the second floor of my parents house, and I had the same problem with too much heat in the summer and too little in the winter. But I kept a R390 on at night and it helped. Plus a few older Heathkit tube radios

73 Richard W4MCD

I'm also looking into replacing the tape with a custom ROM Drawer using the 4041R04 UTILITY PROM file system.

This is described on page 6-2 of the 4041 Utility ROM manual on bitsavers.org.

Basically, tape files can be programmed into a special EPROM installed in the ROM drawer. If the filename is AUTOLD, then the PROM files on that EPROM are automatically used as the system disk on powerup instead of the tape drive.

I have made some progress understanding the 4041 tape file system, by writing a tape dump program that dumps every block on the tape to the comm port, and the data is captured by the PC Realterm application.

The 4041 tape file system is very simple, the tape directory is in four 256 byte blocks at the beginning of the tape. Each file created on the tape is listed in a 16 byte field in one of the tape directory blocks, which includes filename, file type (ITEM or ASCII), starting block, ending block, and time/date stamp.

See the example PROM file system list on page 6-2.

If you run the directory command on a tape with the long parameter: DIR "(long=yes)", you see the start and end blocks.

What is not shown in the description is the format of the EPROM that contains the info that the 4041 recognizes as the PROM file system instead of an option ROM image.

I may have to disassemble the UTILITY ROM code to figure that out.

I believe a hint of the PROM data format is at the end of the UTILITY ROM binary image from 3C40 through 3C9F, which looks like the text displayed at the beginning of a tape directory, and "PROM:" at the end may be the information in the EPROM that triggers the 4041 to use the UTILITY ROM PROM file system. Or the beginning of the PROM may just have code that jumps into the PROM filesystem entry point in the Utility ROM, which would then create the PROM: device from the data in the PROM.

I got the 4041 PROM Accessory Kit user manual from vintagetek.org - they haven't yet posted it on the Tekwiki 4041 page, but it indicates that a 4041 tape in that kit contained the program to 'build' the s-record images that would be used to burn the desired tape files into an EPROM. I have not found that Accessory kit available - it would be nice if one of the forum users has that kit :)

Another very useful Utility ROM feature is listed on page 6-1, the SOFT ROMPACK loader.

This feature loads an option ROM from a 4041 tape file! The bad news is - the option ROM files could be requested from Tektronix if you owned the UTILITY ROM option.

I also plan to experiment with putting my captured OPTION ROM images into tape files and use the UTILITY ROM "Loadroms" call to try to load them into memory.

The Utility ROM manual indicates you cannot load a ROMPACK into memory if the ROMPACK is already installed, so my tests of this feature will be done on my 'older' 4041, where I can remove an option ROM from the drawer and try to load the image from tape.

Monty

Monty

Right after I got my 4041DDU - it stopped working, and I checked the power pins of the floppy drive power connector and?the +5V pin was?only reading 1 volt :( I thought my DDU power supply was at fault, and took?it out of the DDU and powered it with no outputs connected and?the +5V, 12V and 24V outputs were fine.

I put the power supply back into the DDU and just plugged in the floppy power plug, powered on and the floppy connector +5V and +12V voltages checked ok.

Then powered the DDU off and added power to the SCSI controller and cabled up the floppy - powered on and could read the floppy I had created. I even added power to the original hard drive that has the stuck spindle - the?4041 was able to read the directory of the floppy disk I created and the hard disk was reported as unformatted.

Now my 4041 DDU was back to working (floppy drive only) like when I got it last week.

I received a Seagate ST-251 20MB hard disk which I had ordered to try to replace the original stuck Shugart hard disk.? I pulled out the Shugart, plugged in the Seagate drive - and everything powered up. Formatted the Seagate from the 4041 and copied my 4041 tape AUTOLD file to the hard disk. Then powered both the DDU and 4041 off, and turned on the DIP switch to set the DDU hard disk as the SYS DEV device instead of the tape.

Turned on the DDU, waited for the disk to spin up, then turned on the 4041 and the hard drive light flashed?once when the 4041 read the AUTOLD file and my COMM0 console was working fine!

Now I want to experiment using the floppy and hard disk to simplify the process of making the System Verification tapes.

The 5.25 inch double-sided floppy has a formatted capacity of 327 KB, about twice the capacity of the DC100 tape. The 5.25 inch hard disk has a formatted capacity of 10.6 MB (over 32 floppies or 60 tapes).

One missing feature on the 4041DDU floppy and hard drive is multiple directories on a disk. The DDU has a flat file system with six character filenames - like the internal tape drive.

The good news is the 512KB memory capacity of the 4041 can hold all of the files of an entire tape in memory. I'm thinking I can write a single 4041 program that will format and copy all the System Verification files to a tape.

This would dramatically reduced the time required to create a System Verification tape from almost two hours to probably less than one hour.

Monty

Leo,
I have several 7000-series parts-donor plug-ins, but none have that knob. I think the problem is that the items get dropped onto their front face and the knobs get shattered. Then, those parts-only plug-ins that have the knobs get pirated for them to repair the working plug-ins. You might occasionally see new ones on Qservice or Sphere. You have to be patient, sometimes. I wish I could help....
Colin.

Really?
Nobody can or wants to part with one?

According to the RPR (page 144) this one is used in the 5L4N, 7A11, 7A14, 7A15, 7A16, 7A22, 7A29, 7J20, 7L12, 7L13, 7L14, 7S11 and 7S12 plugins.
And in 15 other instruments...

Hi,

I'm just looking for a BNC to flying leads/test pin cable with the small pin connectors for my DC503A. Part number 175-1178-00
I believe they were also used with 7000 series scopes.

Picture here:


I have Paypal ready and standing by for anyone who can send one of these to me in Japan. :)

Thanks!

Really great scan. Thank you!

George

Thanks for the tip Barry. Unfortunately Sphere doesn't have any U550s at this time.
I may be off track or have confirmed that my issue is with the U550 module. Currently I have the 32V, +5V and -5V banks up. The 95V bank still reads about 7.0V. Fuse F558 blows upon powering up the 465M Scope. I.E. when the power button is pull to on.
My latest effort was to remove the 95V jumper and lifting one lead of R541. After which I put a new 0.5A fuse in the F558 holder (It calls for a 0.25A fuse, which I currently don't have any so I thought I'd be safe enough with a 0.5A fuse). Anyway with the jumper removed and a lead of R541 raised, powering up the unit resulted in the F558 fuse blowing immediately.
Contemplating where to go from here.
Harrison N1FAM

Raymond,
Thanks for identifying the plastic part as a dummy module for a TDS2xx scope.? I have since spotted two P/Ns in the molding: 200-4281-02 and 200-4284-01.? If nobody wants it, I'll toss it.
Bruce, KG6OJI