Date   

Re: [OT] Datasheet for NC7033 or NCR7033 NVRAM needed.

Tom Lee
 

The story I'd heard was that Intel learned that silicon nitride is excellent at gettering or otherwise blocking sodium. They pissed away a fortune trying to make a good gate insulator out of the stuff, but threshold stability was even worse than for the oxide they were trying to replace. That Intel was experimenting with nitride was not a well-kept secret, and Moore was asked at a conference about it. His reply was "We found pretty much what we expected." Interpreting that as "nitride is good", AMD and others immediately ramped up their research into nitrides, pissed away fortunes, then angrily approached Moore at yet another conference about his earlier statement. His reply was, "Engineers always expect disappointment, and so we found pretty much what we expected."

-- Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 7/19/2021 18:19, Jim Ford wrote:
Yeah, Tom, I remember reading about Gordon Moore or somebody else at Intel meeting with a gentleman from another semiconductor house and revealing the sodium issue in exchange for the solution to another vexing process problem.  I don't remember the details, but the story was hilarious!  Laugh out loud funny!  Maybe you know the details?       Jim Ford Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Tom Lee <tomlee@ee.stanford.edu> Date: 7/19/21 5:23 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] [OT] Datasheet for NC7033 or NCR7033 NVRAM needed. Early yes, standard not so much.The 7033 is an MNOS (sic) EAROM. The underlying enabling principle was discovered when Gordon Moore punked the entire industry into chasing nitride gates as the solution to MOS's notorious threshold shift problem. Nitrides turned out to be even more unstable then sodium-contaminated oxide (Intel had already pissed away big bucks finding that out; Moore helped everyone else experience the pain). That instability was exploited to make EAROMs, but they could never really stabilize the instability, if you get my meaning. These devices could not tolerate many write cycles. Their primary use was as channel memories in TVs and cable boxes, where reprogramming was a very rare event.The datasheet is the last appendix of the following: http://www.bitsavers.org/pdf/gtc/970005-001_GTC_SW10_Maintenance_Manual_198205.pdfHope this helps. Good luck!-- Cheers,Tom-- Prof. Thomas H. LeeAllen Ctr., Rm. 205350 Jane Stanford WayStanford UniversityStanford, CA 94305-4070http://www-smirc.stanford.eduOn 7/19/2021 16:48, David Slipper wrote:> Sorry for the OT but I'm getting desperate - it's supposed to be a > standard early NVRAM but it and it's data-sheet seem to be unobtanium.>> Regards,> Dave>>>>> >>



Re: Working on the HV Section of a 533A

Keith
 

Guessing you both know the trick about holding a little NE-51 or similar neon bulb in close proximity to the HV section to confirm its operation? If your HV section is working, the little neon will light up from the radiated energy.

Cool to see and an easy way old fashioned service trick to know something is there without having to resort to the high voltage probe, etc.


Keith
Coolblueglow


Re: Working on the HV Section of a 533A

Mark Vincent
 

Jeff,

Brenda is right about the corona dope. Leave those strips in. Clean them to remove dust. I have not seen any of the black beauties any good. These are a wax condenser in a plastic case. I replace them on sight. The Good-all ones I also replace on sight. Replacements I use are Sprague Orange Drops or other high quality ones at 630V, e.g. Panasonic. Radial types work fine to replace axial.

Mark


Re: Working on the HV Section of a 533A

Brenda
 

Hi Jeff, I am glad that I was able to contribute this this forum.

I would have to say, in my opinion, since you started to clean that section, you should keep cleaning it until it is spotless. I have read from another post that you don't clean this section well, that you would actually create leakage and that would throw your HV into chaos. Once it's all clean and dry, you should be able to power it up without any problems. My 545A was filthy, more so than yours most likely was. Mine was covered in all that soot, but was covered in cigarette tar so I had to clean it. I mean, it was pure yellow and sticky and I am not that knowledgeable so I learned the hard way that all this smoke and tar gave me a LOT of HV issues. I am sure that others on this group will chime in as I am still learning about these old scopes with my 535A being my favorite. I would also advise to check and reseat the 12AU7A and the 6AU5GT tubes that are on the underside of the HV oscillator, at least that is what I would do myself.

Brenda


Re: Working on the HV Section of a 533A

 

Brenda,

thanks for that tip; I had never heard of "corona dope" before, but a quick google search (on the correct term) reveals all.

Any idea how I would test be certain that everything is okay? I mean, I guess I can just power the instrument up and wait for the arcing to start, but maybe there are less reckless approaches?

I can guess that I won't simply be able to check resistances, because any leakage would be expected to be at high voltage. I am currently building a small HV power supply in order to test capacitor leakage, but it will only go up to 500 V, and I'm guessing that the voltage on those terminal strips is in the kV range.

-- Jeff Dutky


Re: Working on the HV Section of a 533A

Brenda
 

Hi Jeff! Great to see you are working on your 533A! I have one as well, but it's in really bad shape on the inside. Those 2 back strips is perfectly normal. My 535A and my 545A is like that as well. I read somewhere on the forum that it's called corona dope, since that is where the 10KV is. I think that you will find that after a really good cleaning of the HV board that everything will be just fine. You really do want that coating to be on those last 2 strips, but don't worry, it's really hard to get off. As far as those 2 Black Beauties goes, most likely, those will be just fine. It's a "newer" scope as by this time, Tektronix got rid of the bad capacitors as your HV section has ceramic and those will be just fine as well. I have a few scopes that use these Black Beauties with the red writing to be fully functional. The ones with the yellow writing are most likely going to be very leaky.

Brenda


Working on the HV Section of a 533A

 

Fresh off of several victories with my 7603 and plug-ins, I turned my attention tonight to the 533A and found the courage to peek inside the left half of the HV section (the section on the opposite side from the CRT, with the five 5642 rectifier tubes). The section was entirely covered in soot, which is expected where you have high voltage, but after I got done cleaning the soot off of everything a possibly serious problem became apparent: two of the ceramic terminal strips at one end of the row of rectifiers was still pitch black.

I have uploaded pictures of the HV section to this album: https://groups.io/g/TekScopes/album?id=266270

I have already ordered replacement ceramic terminal strips, but I don't really know what I'm doing. I assume that I will need to unsolder the rectifier tubes both to replace the terminal strips, and to verify that there isn't more damage to components beneath the rectifiers.

I'm also wondering if I'm going to need to replace those black axial leaded capacitors that can be seen in the foreground. I think that there are more like that elsewhere in the scope, but I have done a detailed inventory yet. If I need to replace them, what do I replace them with?

Any advice is appreciated.

-- Jeff Dutky


Re: [OT] Datasheet for NC7033 or NCR7033 NVRAM needed.

Jim Ford
 

Yeah, Tom, I remember reading about Gordon Moore or somebody else at Intel meeting with a gentleman from another semiconductor house and revealing the sodium issue in exchange for the solution to another vexing process problem.  I don't remember the details, but the story was hilarious!  Laugh out loud funny!  Maybe you know the details?       Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Tom Lee <tomlee@ee.stanford.edu> Date: 7/19/21 5:23 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] [OT] Datasheet for NC7033 or NCR7033 NVRAM needed. Early yes, standard not so much.The 7033 is an MNOS (sic) EAROM. The underlying enabling principle was discovered when Gordon Moore punked the entire industry into chasing nitride gates as the solution to MOS's notorious threshold shift problem. Nitrides turned out to be even more unstable then sodium-contaminated oxide (Intel had already pissed away big bucks finding that out; Moore helped everyone else experience the pain). That instability was exploited to make EAROMs, but they could never really stabilize the instability, if you get my meaning. These devices could not tolerate many write cycles. Their primary use was as channel memories in TVs and cable boxes, where reprogramming was a very rare event.The datasheet is the last appendix of the following: http://www.bitsavers.org/pdf/gtc/970005-001_GTC_SW10_Maintenance_Manual_198205.pdfHope this helps. Good luck!-- Cheers,Tom-- Prof. Thomas H. LeeAllen Ctr., Rm. 205350 Jane Stanford WayStanford UniversityStanford, CA 94305-4070http://www-smirc.stanford.eduOn 7/19/2021 16:48, David Slipper wrote:> Sorry for the OT but I'm getting desperate - it's supposed to be a > standard early NVRAM but it and it's data-sheet seem to be unobtanium.>> Regards,> Dave>>>>> >>


Re: [OT] Datasheet for NC7033 or NCR7033 NVRAM needed.

Tom Lee
 

Aargh. "more unstable than", not "more unstable then", of course!

Aargh. Ptth.

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 7/19/2021 17:23, Tom Lee wrote:
Early yes, standard not so much.

The 7033 is an MNOS (sic) EAROM. The underlying enabling principle was discovered when Gordon Moore punked the entire industry into chasing nitride gates as the solution to MOS's notorious threshold shift problem. Nitrides turned out to be even more unstable then sodium-contaminated oxide (Intel had already pissed away big bucks finding that out; Moore helped everyone else experience the pain). That instability was exploited to make EAROMs, but they could never really stabilize the instability, if you get my meaning. These devices could not tolerate many write cycles. Their primary use was as channel memories in TVs and cable boxes, where reprogramming was a very rare event.

The datasheet is the last appendix of the following: http://www.bitsavers.org/pdf/gtc/970005-001_GTC_SW10_Maintenance_Manual_198205.pdf

Hope this helps. Good luck!

-- Cheers,
Tom


Re: [OT] Datasheet for NC7033 or NCR7033 NVRAM needed.

Tom Lee
 

Early yes, standard not so much.

The 7033 is an MNOS (sic) EAROM. The underlying enabling principle was discovered when Gordon Moore punked the entire industry into chasing nitride gates as the solution to MOS's notorious threshold shift problem. Nitrides turned out to be even more unstable then sodium-contaminated oxide (Intel had already pissed away big bucks finding that out; Moore helped everyone else experience the pain). That instability was exploited to make EAROMs, but they could never really stabilize the instability, if you get my meaning. These devices could not tolerate many write cycles. Their primary use was as channel memories in TVs and cable boxes, where reprogramming was a very rare event.

The datasheet is the last appendix of the following: http://www.bitsavers.org/pdf/gtc/970005-001_GTC_SW10_Maintenance_Manual_198205.pdf

Hope this helps. Good luck!

-- Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 7/19/2021 16:48, David Slipper wrote:
Sorry for the OT but I'm getting desperate - it's supposed to be a standard early NVRAM but it and it's data-sheet seem to be unobtanium.

Regards,
Dave






[OT] Datasheet for NC7033 or NCR7033 NVRAM needed.

David Slipper
 

Sorry for the OT but I'm getting desperate - it's supposed to be a standard early NVRAM but it and it's data-sheet seem to be unobtanium.

Regards,
Dave


Re: Looking for data on 9-pin Vacuum time delay relays used in old Tek-scopes

Morris Odell
 

A few years ago the time delay relay in my 555 died and lacking a replacement I had to cobble up a substitute. I repurposed an old device I had made to trigger a super 8 movie camera (remember them?) for time lapse. That device was designed to work form a 9 volt battery. I started by rectifying the 6.3 volt supply for the time delay relay using a half wave voltage doubler with the input capacitor deliberately kept to a small value to allow the output voltage across the storage cap to rise slowly. When it got to a suitable level it triggered a SCR through a zener diode to discharge the output cap through the coil of a little relay to close the main scope relay. Once the scope relay pulls in the 6.3 supply is disconnected from the voltage doubler. A reverse biased diode from the storage cap to the +100 volt line removes any residual charge as soon as the scope is switched off so the time delay will function properly next time it's switched on.

There's plenty of room in the 555 power supply for small proto board with the circuit on it. All the parts were in my junque box so the whole thing cost nothing and provided a bit of fun.

In retrospect it would have been even simpler to slowly charge a cap from the raw +100 supply which is about +165 volts according to the manual, and use that to trigger the SCR..

Morris


Re: Computer interface to 576

teamlarryohio
 

Appears to be the same one from about a year and a half ago.
Lots of posts in the archives.


Re: 2712 SA with display (and normalization) issues #photo-notice

 

On Mon, Jul 19, 2021 at 03:27 PM, Colin Herbert wrote:


Have you looked here?

https://w140.com/tekwiki/wiki/2712

Not OCR, but probably useful. Failing that, try Artek Manuals (
http://artekmanuals.com/ ). They don't have it listed but they might be able
to help.
OCR'ed version added.

Raymond


Re: ++Processor error on TDS 754D on startup

pmoyle111
 

Thanks for the response. If endeavoring to do this (rtc + ram), there are already a number of folks that claim to have working solutions, so I would search out their progress and find the flaws and try to find elegant workarounds. The easiest way is to find compatible no-batt rtc, and add logic around that to extend the ram. Maybe easiest is to used the latest version of the original MC148616 and i/f logic and add an fram if the are any parallel i/f available - the original has muxed a/d so that would have to be demuxed. Goal would be to try to get away with a bunch of glue logic in an XC9536 or 72. To try to recreate the ds1486 from scratch would take a tremendous verification/validation effort with no payback. Seems like a lot of nuances present. Mot's original MC14xx had battery discharge bugs which was one of the Dallas popularities. Mot fixed it in the b version.

Most modern designs use an i2c rtc and an fram. So, other than legacy sockets, not much market.

pmoyle


Re: ++Processor error on TDS 754D on startup

EricJ
 

Yes the 754s are really good scopes. I've got two, an A and a D. I am dreading the day when I need to get after this problem. I've already backed up the contents of the NVRAM via the floppy drive method, so I'm ready if I need to do it, but not looking forward to it.--EricSent from my Galaxy

-------- Original message --------From: BobH <wanderingmetalhead@dakotacom.net> Date: 7/19/21 9:03 AM (GMT-06:00) To: TekScopes@groups.io Subject: Re: [TekScopes] ++Processor error on TDS 754D on startup Thanks for the information. The reason that I was asking is that I have been working on a replacement for the battery backed SRAMs. I currently have an 8Kx8 board design that I am testing. It does not support timekeeping right now. Backup power is supplied by a socketed coin cell on top of the board.I looked at the two part numbers you supplied, the DS1486 has RAM and a clock on board, and is obsolete with 0 stock at Mouser. The DS1250Y is a 512Kx8 SRAM which would be more approachable for a homebrew fix, but they are still available with Mouser having them in stock. They are expensive though.On the boards that I am working on, they are using the DIP package. I have been looking at adding timekeeping to my design, but that is going to get a lot more complex, as it will require an FPGA to allow formatting the data to emulate the various module part numbers. Also, 5V tolerant FPGAs are getting scarce.Good Luck with your 754D, those are nice scopes!BobH


Re: 7904A compress sweep

Mark Vincent
 

Tom,

Use 91% IPA for the coax inputs and socketed transistors. I use a small artist brush to apply the IPA then move then move them up and down in their sockets a few times to clean them. You do this to the neck pins and sockets also. Dirty contact(s) would be the most likely cause of your trouble.

I think you mean the hot transistors are the 900 numbers. I have three two fin Thermalloy 2225C heatsinks on three of them. There is not enough room for all four to have this type of heatsink on them. The heatsinks on mine are on Q900, Q930 and Q940. I used MX-4 compound.

In mine, I replaced C100 with a film type and the two 22mfd with ULD 47mfd 25V. R921 and R954 are now, in mine, 1W 1% and R900, R941 and R960 are 2w 1% types. I had these parts in stock. These resistors are off the board to allow air all around the bodies of the resistors. I did add compound on the two pars if transistors with the metal band around them to further aid in thermal coupling. You do what you want with your piece. I did what I wanted to in my piece. Mine works fine.

My B time base socket on the main board had bad/no solder on the two coax output from the time base. This was a factory defect. No one had worked on this after it was originally bought. The spring tension wire was off its pin. I took these off, repaired the problems then put back in. Now it works. The two plastic covers were carefully removed to do the work. I know what I had is a rare defect.

Mark


Re: 7904A compress sweep

Harvey White
 

If the trace can center, then the circuit is in balance as far as the + section and - section are concerned, putting the same voltage on the plates.

There is, however, no guarantee that it's the *right* voltage.

I'd center the trace, or duplicate the test conditions in the manual, then go through and check the static voltages on each transistor.  Running each output at, say, twice the current will still give you deflection, but it will bottom out, for instance.

Did you check the emitter supply resistor (and bypass capacitor) for the emitter supply circuits of the balanced pairs?

Harvey

On 7/19/2021 8:46 AM, Tom Phillips wrote:
Thanks for suggestions

I moved the gain pot slightly but it has little effect.

The power supply voltages are very close to spot on and stable but the four metal output transistors Q610, 20 30 and Q640 are definitely hot. I'm in the middle of a long distance move and don't have another scope handy at the moment to check stage waveforms but if needed are equivalents for motorola ST919/ST7394 available? Casual web search not turning up much.







Re: Binding Post Thumb/Head Nut Replacements

 

Renée,

The "originals" are the two "steel" finish nuts with diamond knurling on the bottom. The replacements are the black oxide finish and brass nuts on the top.

-- Jeff Dutky


Re: ++Processor error on TDS 754D on startup

BobH
 

Thanks for the information. The reason that I was asking is that I have been working on a replacement for the battery backed SRAMs. I currently have an 8Kx8 board design that I am testing. It does not support timekeeping right now. B
ackup power is supplied by a socketed coin cell on top of the board.

I looked at the two part numbers you supplied, the DS1486 has RAM and a clock on board, and is obsolete with 0 stock at Mouser. The DS1250Y is a 512Kx8 SRAM which would be more approachable for a homebrew fix, but they are still available with Mouser having them in stock. They are expensive though.

On the boards that I am working on, they are using the DIP package. I have been looking at adding timekeeping to my design, but that is going to get a lot more complex, as it will require an FPGA to allow formatting the data to emulate the various module part numbers. Also, 5V tolerant FPGAs are getting scarce.

Good Luck with your 754D, those are nice scopes!
BobH

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