Re: Tek Scopes found in old picture book
Did you look online at any pics of the SS-5706? Looks like a pretty close match to me.
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
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On 7/28/2021 10:26, Jim Ford wrote: Hmmm, I'm not seeing anything that looks like any of the Iwatsu scopes I'm familiar with.? I used to have 3 of them; can't remember model numbers, but they did have 60, 100, and 250 MHz bandwidths.? ?The 60 MHz one had a DMM and frequency counter on top.? Obviously copied from Tek 400 series scopes, but why own Iwatsu when you could own Tek?? So I sold them all and bought several Tek 7000 and 5000 series scopes. :)? ? ? ? ? ?Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Tom Lee <tomlee@...> Date: 7/28/21 9:30 AM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Tek Scopes found in old picture book Offhand, I'd say that it is an Iwatsu, maybe an SS-5706.Tom-- Prof. Thomas H. LeeAllen Ctr., Rm. 205350 Jane Stanford WayStanford UniversityStanford, CA 94305-4070 7/28/2021 09:11, Carsten Bormann wrote:> On 2021-07-28, at 17:02, Dave Peterson via groups.io <davidpinsf@...> wrote:>> And are those 400 series scopes I see hints of (blue screens) on the far right of the racks?> My brain tells me that I saw Hamegs in the rack when I visited seven years ago.>> My picture at is not clear enough to read what¡¯s on the scope in the rack; it doesn¡¯t shout ¡°Hameg¡± at me either.> It doesn¡¯t look to me like a 475 or some such.>> Gr¨¹?e, Carsten>>>> >>
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Re: Tek Scopes found in old picture book
Hmmm, I'm not seeing anything that looks like any of the Iwatsu scopes I'm familiar with.? I used to have 3 of them; can't remember model numbers, but they did have 60, 100, and 250 MHz bandwidths.? ?The 60 MHz one had a DMM and frequency counter on top.? Obviously copied from Tek 400 series scopes, but why own Iwatsu when you could own Tek?? So I sold them all and bought several Tek 7000 and 5000 series scopes. :)? ? ? ? ? ?Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: Tom Lee <tomlee@...> Date: 7/28/21 9:30 AM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Tek Scopes found in old picture book Offhand, I'd say that it is an Iwatsu, maybe an SS-5706.Tom-- Prof. Thomas H. LeeAllen Ctr., Rm. 205350 Jane Stanford WayStanford UniversityStanford, CA 94305-4070 7/28/2021 09:11, Carsten Bormann wrote:> On 2021-07-28, at 17:02, Dave Peterson via groups.io <davidpinsf@...> wrote:>> And are those 400 series scopes I see hints of (blue screens) on the far right of the racks?> My brain tells me that I saw Hamegs in the rack when I visited seven years ago.>> My picture at is not clear enough to read what¡¯s on the scope in the rack; it doesn¡¯t shout ¡°Hameg¡± at me either.> It doesn¡¯t look to me like a 475 or some such.>> Gr¨¹?e, Carsten>>>> >>
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
I bought a reel of 5000 - Vishay HER105-T High Efficiency 400V 1A DO41
Diodes, a couple years ago for under $23.
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On Wed, Jul 28, 2021 at 12:34 PM Tom Lee <tomlee@...> wrote: A series string of UF4007s with a 10kV breakdown voltage would have of
the order of 1pF capacitance. The problem with 1N4007s is with their
slow reverse recovery (hence the UF4007 recommendation). But reverse
recovery is distinct from junction capacitance.
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Re: 7000 test/cal module(s) and backplane breakout board.
I see that, thanks - I'm going to take a look at the schmitt trigger input circuitry with diode clamps you use and experiment some. Need to look at the trade-offs between the two approaches, I always relish having options to consider. In my experience any adequately interesting engineering problem contains trade-offs that take time to consider, the no-brainer decisions are not really the interesting problems. Appreciate the discussion, I do think that creating a modern toolkit to keep 7000 (and possibly 5000) mainframes in top working order without relying on a diminishing pool of original cal fixtures will pay off. I do not feel any responsibility to create the one-and-only-perfect-fixture, but am excited that as a community we can have a set of proven circuits that can be mixed-and-matched, improved, tweaked, etc. On Wed, Jul 28, 2021 at 11:31 AM Ed Breya via groups.io <edbreya= [email protected]> wrote: OK, I managed to scan my old readout exerciser schematic, posted here:
/g/TekScopes/album?id=266548
Now I'm remembering some details. I had to do some tricks to skip certain
parts of the code table and functions, so only the character set would
show. It does not test any of the other RO functions. For a universal type
interface/test setup, you'd want to have all of the code table available,
using the full current ranges. Another reason to use IC DACs, is that you
can include the provision for limit testing. Rather than just the nominal
current steps from a 4-bit DAC, with say 8 bits, you could tweak the values
around to check where the readout decides the values.
Ed
-- Andy
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
A series string of UF4007s with a 10kV breakdown voltage would have of the order of 1pF capacitance.? The problem with 1N4007s is with their slow reverse recovery (hence the UF4007 recommendation). But reverse recovery is distinct from junction capacitance.
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
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On 7/28/2021 09:29, greenboxmaven via groups.io wrote: The idea of replacing tube rectifiers in TVs and other CRT devices is an old one. One of the most important considerations is the capacitance of the reverse biased diode. The higher the current capacity of a silicon rectifier, the higher the capacitance. Many TVs would have serious horizontal linearity issues as well as reduced high voltage when a solid state rectifier was substituted.? A string of 1N4007 diodes would likely have too much capacitance, especially at the 40 KC or higher frequency a scope high voltage supply usually operates at. A high voltage rectifier has several carefully designed and/or chosen junctions in series to share the reverse voltage, 1N4007 diodes may not balance their reverse voltage sharing properly. They are almost always used with balancing resistors in high voltage power supplies.
??? Bruce Gentry, KA2IVY
On 7/28/21 11:45, saipan59 (Pete) wrote:
Just wondering: Is it feasible to replace a 5642 with a string of (for example) cheap 1N4007's?
I don't have a need to do this at the moment, but I already have a bunch of them.
Pete
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Re: 7000 test/cal module(s) and backplane breakout board.
OK, I managed to scan my old readout exerciser schematic, posted here: /g/TekScopes/album?id=266548Now I'm remembering some details. I had to do some tricks to skip certain parts of the code table and functions, so only the character set would show. It does not test any of the other RO functions. For a universal type interface/test setup, you'd want to have all of the code table available, using the full current ranges. Another reason to use IC DACs, is that you can include the provision for limit testing. Rather than just the nominal current steps from a 4-bit DAC, with say 8 bits, you could tweak the values around to check where the readout decides the values. Ed
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Re: Tek Scopes found in old picture book
Offhand, I'd say that it is an Iwatsu, maybe an SS-5706.
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
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On 7/28/2021 09:11, Carsten Bormann wrote: On 2021-07-28, at 17:02, Dave Peterson via groups.io <davidpinsf@...> wrote:
And are those 400 series scopes I see hints of (blue screens) on the far right of the racks? My brain tells me that I saw Hamegs in the rack when I visited seven years ago.
My picture at is not clear enough to read what¡¯s on the scope in the rack; it doesn¡¯t shout ¡°Hameg¡± at me either.
It doesn¡¯t look to me like a 475 or some such.
Gr¨¹?e, Carsten
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
The idea of replacing tube rectifiers in TVs and other CRT devices is an old one. One of the most important considerations is the capacitance of the reverse biased diode. The higher the current capacity of a silicon rectifier, the higher the capacitance. Many TVs would have serious horizontal linearity issues as well as reduced high voltage when a solid state rectifier was substituted.? A string of 1N4007 diodes would likely have too much capacitance, especially at the 40 KC or higher frequency a scope high voltage supply usually operates at. A high voltage rectifier has several carefully designed and/or chosen junctions in series to share the reverse voltage, 1N4007 diodes may not balance their reverse voltage sharing properly. They are almost always used with balancing resistors in high voltage power supplies.
??? Bruce Gentry, KA2IVY
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On 7/28/21 11:45, saipan59 (Pete) wrote: Just wondering: Is it feasible to replace a 5642 with a string of (for example) cheap 1N4007's?
I don't have a need to do this at the moment, but I already have a bunch of them.
Pete
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Re: Tek Scopes found in old picture book
On 2021-07-28, at 17:02, Dave Peterson via groups.io <davidpinsf@...> wrote:
And are those 400 series scopes I see hints of (blue screens) on the far right of the racks?
My brain tells me that I saw Hamegs in the rack when I visited seven years ago. My picture at is not clear enough to read what¡¯s on the scope in the rack; it doesn¡¯t shout ¡°Hameg¡± at me either. It doesn¡¯t look to me like a 475 or some such. Gr¨¹?e, Carsten
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
Yep. 1N400x devices are very slow to turn off; they are charge sponges that rectify as a side effect. UF4007s would be a much better choice.
As to equalizing networks (R and/or C), if the individual rectifiers all came from the same batch, I haven't found them to be necessary. Adjacent devices from an SMD reel or strip will be from the same batch, to a high probability.
The ST app note I linked to earlier has much more detailed information.
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
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On 7/28/2021 09:04, SCMenasian wrote: It appears that the high voltage power supply runs at ~60kHz. I wouldn't trust a garden variety silicon diode like 1N400x to hack it. Fast recovery diodes might be OK but you might need to take precautions to ensure that the high frequency voltage is distributed evenly along the string.
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
It appears that the high voltage power supply runs at ~60kHz. I wouldn't trust a garden variety silicon diode like 1N400x to hack it. Fast recovery diodes might be OK but you might need to take precautions to ensure that the high frequency voltage is distributed evenly along the string.
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
Absolutely! Silicon HV rectifiers beyond a kV or so are actually made of series strings of lower-voltage units. A clue is their much higher forward voltages (which makes them difficult to test with conventional DMMs).
One consideration is ensuring even partitioning of the reverse voltage across the individual diodes. If the diodes all came from the same wafer, you generally won't have to worry about adding shunt resistors, especially if you're not trying to push the limits of breakdown voltage. There's a lot more detail in this app note from ST:
-- Cheers
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
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On 7/28/2021 08:45, saipan59 (Pete) wrote: Just wondering: Is it feasible to replace a 5642 with a string of (for example) cheap 1N4007's?
I don't have a need to do this at the moment, but I already have a bunch of them.
Pete
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
Regular 1n4007s are too slow. UF4007s are fast enough, but it's easiest to just get proper HV rectifiers (which are actually made from strings of series diodes inside).
Ed
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Re: Tek Scopes found in old picture book
On 28. Jul 2021, at 09:07, Carsten Bormann <cabocabo@...> wrote:
...Yes. See the picture at I like the large black resistors to the right of their heads. Look like oversized fuses in their holders... In the original pic I didn't notice all the tubes on top of the shelves. What are they for? Are these thyratrons? My first guess leant towards analogue computers, thinking there were operational amplifiers all over. Stupid me, I even read about that Manchester Baby some months ago. cheers Martin
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
Just wondering: Is it feasible to replace a 5642 with a string of (for example) cheap 1N4007's?
I don't have a need to do this at the moment, but I already have a bunch of them.
Pete
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Re: Tek Scopes found in old picture book
That makes perfect sense, thanks Carsten!
Looking forward to the goods :-)
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On Wed, Jul 28, 2021 at 9:07 AM Carsten Bormann <cabocabo@...> wrote:
Williams tube.
Gr¨¹?e, Carsten You might be talking about the loose tube in a box at the bottom of
the picture. I mean a rack mounted unit between the two PCs.
Yes. See the picture at
(because of the inexplicable restriction on sending attachments on this list, I just put it up in a random location. Copy that into the groups.io archive if you can stomach navigating that entirely unneeded bureaucracy) ¡ª zoom in to see the faint green image of the bits.
There are
two scopes and a third thing, in the rack, that also looks like a
scope. A Williams tube device has no front display because the front
of the tube is covered by the read-out plate. The problem is ¡ª how do you debug a Williams tube?
I seem to remember that the makers of the Manchester Baby (SSEM [1]) just put another tube on the same signals so they could see what was written to the storage tubes (ah, [2] has the details). During restoration, they couldn¡¯t get the original size display tube, so they have a half-size in the rack now.
BTW I tried getting in touch off list but haven't heard back :) Would
you mind checking :) thanks Everything is on its way, thank you.
Gr¨¹?e, Carsten
[1]:
[2]:
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Re: Tek Scopes found in old picture book
And are those 400 series scopes I see hints of (blue screens) on the far right of the racks?
I'm back from our travels, but the book is now packed away in the shipment bound for home. I'll look up the picture credits when it arrives.
I could be wrong, but in my scan of the text when I came across the picture didn't say anything about the Manchester Baby, restoration, or anything of note w.r.t. the picture. I'm curious to read it now to see what it does say. I'm glad I brought it up with you all. What a fascinating back story. I'd love to give credit to the photographer, and wonder what his involvement was. Perhaps there's more to be had there? Unfortunately it has been a few years since.
My wife and I both worked at Intel back in the 90s. Actually never knew each other while there, but that's another story. Talk about getting off topic! This book must have been a 30th anniversary thing, and I'd left by then. I suspect she gifted this to her parents - we'd just met, so I don't ever recall seeing it before. Well, maybe. I recall Intel being a pretty fun place to work, and recall being rewarded nicely at times, and chastised by Andy at other times. I appreciated the gifts. Still have one sitting right behind the monitor I'm looking at. As well as my office art which is a layout plot of my first design there. Intel was my first job out of school, so I guess left a lasting impression. Probably why we decided to keep the book. Now my kids can deal with it when it's time to clean out my house! Along with a few scopes.
Thanks all for the background.
Dave
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On Wednesday, July 28, 2021, 2:02:00 AM PDT, mikecaa <4sumik@...> wrote:
Think it's a replica Manchester baby at the Manchester computer museum. See below;
Regards - Mike
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Re: 7000 test/cal module(s) and backplane breakout board.
Schematic fixed, thanks for pointing out the error.
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On Tue, Jul 27, 2021 at 11:46 PM Andy Warner <andyw@...> wrote: You are right about Q1-4, I was in a rush, will fix it tomorrow.
I can test things with a simple current mirror, but I usually resort to a
Wilson if I am not using matched parts. Just habit, perhaps a bad one.
On Tue, Jul 27, 2021 at 23:33 Ed Breya via groups.io <edbreya=
[email protected]> wrote:
Looks about right, except the PNPs appear upside down. If you're going
with emitter ballast resistors in the mirror, then you probably don't need
transistor matching or the Wilson configuration, and two NPNs per mirror
would suffice. The compliance is pretty much constant since the row and
column nodes hold very close to ground - there's hardly any Early effect.
Ed
-- Andy
--
Andy
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Re: Tek Scopes found in old picture book
Think it's a replica Manchester baby at the Manchester computer museum. See below;
Regards - Mike
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Michael A. Terrell
Martin
saipan59 (Pete)
Dave Peterson
mikecaa