Hi Albert,
I tested your suggested setup and it does indeed have a positive effect. With a 7B53A in the B slot and set up to display a delayed trace, if I turn the B INTENSITY pot fully CW and then adjust the main INTENSITY control to see the trace without any observable highlighting. I can then rotate the B INTENSITY pot slowly CCW, I can start seeing the dual intensities and the highlighted one is not excessively bright. I can then make slight adjustments to both pots to where a clean, dual-intensity trace is displayed.
Is this the way the two INTENSITY controls should be used? I have been setting the A/B INTENSITY pots such that with the main INTENSITY pot at about 12:00 to 1:00 o'clock, the "basic" trace is visible and it was then if I elected to display a highlighted, delayed trace, I would see the excessively bright part of the trace. Perhaps this is merely operator error?
Thanks!
Barry - N4BUQ
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----- Original Message ----- From: "Albert Otten" <aodiversen@...>
To: "tekscopes" <[email protected]>
Sent: Friday, November 19, 2021 8:11:48 AM
Subject: Re: [TekScopes] 7704A - Grid Bias Hi Barry,
A month ago this was the "complaint" in your starting message of this topic:
If a any of my time bases are set to display a highlighted trace, the trace is
very much too bright. If I'm understanding this function correctly, the
plugins are setting a voltage on the AUX Z AXIS line. If this were one or two
plugins, I'd suspect the signal being set on AUX Z-AXIS being incorrect, but
since this is occurring on all of them, I suspect something is misadjusted in
the CRT circuit of the 7704A. I suppose you used a dual time base like 7B53A in the A slot, though my same
remarks hold just as well for the 8B55/7B80 combo.
In both 7704As I tested with 7B53A the brightness contrast is *extremely*
influenced by the A INTEN setting. With A INTEN at maximum there is hardly a
visible contrast. But with just a slight amount below maximum the unintensified
portion vanishes. It's difficult to find a compromise. With 7B85/7B80 this goes
somewhat better.
In the fully CW position the wiper of the INTEN pot should make contact with
-15V. The pot is very well accessible if you remove the upper-right cabinet
panel. Maybe you have to exercise the pot a few times.
In my 7B53A the active intensifying voltage at TP620 is about -0.95 V.
[BTW Here is the simplified reason why A INTEN is so important for the contrast,
in stead of INTENSITY. In the Z-axis logic IC U2587<3> the effects of A INTEN
and Aux Z-axis are summed. The result (sink current) goes as Z-axis Signal to
the Z-axis board<14>. There the INTENSITY setting determines which fraction of
the Z-axis Signal passes via Q4175 (and really sets the CRT intensity) and
which remaining fraction passes via Q4163 (and gets lost). So INTENSITY effect
is not additive there to the A INTEN component but multiplicative to both
components].
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as my scope serial number is a million Quadzillatech: The Guernsey scopes and plugins have a 6 digit number. Your number 1009919 looks invalid. Perhaps you can compare component date codes in the FET circuits with those in the rest of the scope. The non-military service manual 070-0755-02 for S/N above 20000 is available here: Albert
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Re: 172 programmable test fixture plastic latch modelling effort for 3D print replacement (105-0286-00)
On Thu, Nov 18, 2021 at 10:26 PM Gregor Lasser <gregor.lasser@...> wrote: For those of you that have in the past created 3D models to replicated
Tektronix parts I would encourage you to add them to the new 3D printing
site on Tekwiki:
What a great idea! I added my model for 351-0449-00, the FG504 et al PCB bracket.
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I'm betting that this is a Guernsey Produced scope. If you are certain about it being an original FET (late) model, then the conversation regarding the location and values of R471 and R675 is a moot point, as they were not used in the FET models.
Late model Manual is here:
Good Luck!
--
Michael Lynch
Dardanelle, AR
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as my scope serial number is a million+ i am sure its a fet model as standard and not converted,can someone point me to a link for the service manual for this
late model 453?,need to be singing from the same hymn sheet!,cheers,also is a conversion from the hv tube diodes to the solid state ones viable?,as i have a parts 453a that the hv transfo arced on so is scrap but the psu hv diodes are ok.
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Re: You never know where Tek stuff will show up
Dave,
I know how you feel. I once came across a similar clearance where the relatives clearing it out told me what they gave away in the form of HP & Tek test equipment. I commented to them that I hoped that it went to a good home. They said that they gave it to someone who had no idea as to what it was but it ¡°looked science-fiction-ish¡± and ¡°had a lot of knobs and dials.¡±
When working in Denver back in the 70¡¯s I would occasionally go to the federal surplus sales. In those days they held a lot of stand-up sales where you would actively bid in real time on some very nice test equipment amongst other bidders. At virtually every sale there was this fellow who would show up looking rather homeless, wearing greasy coveralls and shuffling around closely eyeing every piece of test equipment. During bidding he would frequently out-bid every one. At the end of the sale he would pull out a large roll of bills and pay for everything in cash then he and another fellow would back a large van up to the loading dock and proceed to throw ¨C I say ¡°throw¡± with honesty - all of the equipment into the back of the truck. I winced with the landing of each piece of hardware. I suspect that he was contract work for one of the then big used equipment dealers of that era.
If you value legacy test equipment, things like this will come to haunt you for years.
Greg
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Yes, I believe there was a mod kit to convert nuvistor 453 to FET. I don¡¯t have the kit¡¯s part number. Dave Wise From: [email protected] [mailto: [email protected]] On Behalf Of Michael W. Lynch via groups.io Sent: Friday, November 19, 2021 9:20 AM To: [email protected]Subject: Re: [TekScopes] 453 trigger issues On the later 400 series Tek scopes (and many others as well), serial numbers beginning in "1" were produced at Guernsey. I do not know if this holds true for the 453. But it is very possible that this is a Guernsey produced instrument. "Early" s/n Scopes (019999 and below) were originally produced with NUVISTOR's and should be the only instruments equipped with these two resistors in their respective circuits. If yours is a later model scope, then, according to the schematics. it will not have R471 or R675. If these two resistors are present in the scope, then it was originally produced with NUVISTOR's or has an older model board installed (if this is even possible). I am far from an expert on these scopes, but I seem to remember that there was a way to convert older models from NUVISTORS to FET's You definitely need to make sure that your instrument and your service manual are for the correct serial number range. . I have a 453, but it us a "High" serial numbered unit. -- Michael Lynch Dardanelle, AR
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On the later 400 series Tek scopes (and many others as well), serial numbers beginning in "1" were produced at Guernsey. I do not know if this holds true for the 453. But it is very possible that this is a Guernsey produced instrument.
"Early" s/n Scopes (019999 and below) were originally produced with NUVISTOR's and should be the only instruments equipped with these two resistors in their respective circuits.
If yours is a later model scope, then, according to the schematics. it will not have R471 or R675.
If these two resistors are present in the scope, then it was originally produced with NUVISTOR's or has an older model board installed (if this is even possible).
I am far from an expert on these scopes, but I seem to remember that there was a way to convert older models from NUVISTORS to FET's
You definitely need to make sure that your instrument and your service manual are for the correct serial number range. .
I have a 453, but it us a "High" serial numbered unit.
--
Michael Lynch
Dardanelle, AR
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I dont know if it helps but this scope was built in 1965,well the pcb's were.
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This has fets not nuvistors,it does have valve/tube doides in the hv supply if that helps,the scope doesent have made in gurnsey on it like some ive seen,incidentaly R467 measures 309 ohm and R776 315 ohm,so r776 is just on the edge of the 5% tolerance. i missread the serial,its 1009919.
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On Fri, Nov 19, 2021 at 08:56 AM, <quadzillatech@...> wrote:
also r471 and r675 are missing on my parts list/schematics also not on the
board pics either ref 4.19 /4.20 / 4.21 of the manual,are there different
revisions for this scope?,the manuaual doesent tally 100% with what i have in
front of me,mines serial number :100917,cheers Paul m3vuv.
It occurs to me that you may be looking at an early model instrument and a late model manual. Comparing the manuals that I have, the schematics indicate that R471 and R675 are only used on "low" serial numbered Units (B020000 and below). These scopes are the one originally equipped with NUVISTOR Tubes. If R471 and R675 are present in your scope, then you have an "Early" instrument. It is important to get the manual that matches the scope. Does your s/n Begin with a "B" or is it all numeric? A serial number that begins with a "1" would be a scope assembled at Guernsey, Channel Islands. . . -- Michael Lynch Dardanelle, AR
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Re: tek 2215 trace position issues
well,the replacement transistors are fitted,no difference ,does anyone know how to remove the knobs that have no allen grub screws?,i cant see how to remove them,i guess i need to get to the boards behind the front panel to make measurements,it looks imposible with the front on the scope.TIA
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also r471 and r675 are missing on my parts list/schematics also not on the board pics either ref 4.19 /4.20 / 4.21 of the manual,are there different revisions for this scope?,the manuaual doesent tally 100% with what i have in front of me,mines serial number :100917,cheers Paul m3vuv.
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i cant find r471 or r675 on the parts list or schematic,any idea what value they should be?,cheers Paul.
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Hi Barry, A month ago this was the "complaint" in your starting message of this topic: If a any of my time bases are set to display a highlighted trace, the trace is
very much too bright. If I'm understanding this function correctly, the
plugins are setting a voltage on the AUX Z AXIS line. If this were one or two
plugins, I'd suspect the signal being set on AUX Z-AXIS being incorrect, but
since this is occurring on all of them, I suspect something is misadjusted in
the CRT circuit of the 7704A. I suppose you used a dual time base like 7B53A in the A slot, though my same remarks hold just as well for the 8B55/7B80 combo. In both 7704As I tested with 7B53A the brightness contrast is *extremely* influenced by the A INTEN setting. With A INTEN at maximum there is hardly a visible contrast. But with just a slight amount below maximum the unintensified portion vanishes. It's difficult to find a compromise. With 7B85/7B80 this goes somewhat better. In the fully CW position the wiper of the INTEN pot should make contact with -15V. The pot is very well accessible if you remove the upper-right cabinet panel. Maybe you have to exercise the pot a few times. In my 7B53A the active intensifying voltage at TP620 is about -0.95 V. [BTW Here is the simplified reason why A INTEN is so important for the contrast, in stead of INTENSITY. In the Z-axis logic IC U2587<3> the effects of A INTEN and Aux Z-axis are summed. The result (sink current) goes as Z-axis Signal to the Z-axis board<14>. There the INTENSITY setting determines which fraction of the Z-axis Signal passes via Q4175 (and really sets the CRT intensity) and which remaining fraction passes via Q4163 (and gets lost). So INTENSITY effect is not additive there to the A INTEN component but multiplicative to both components].
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would these work in my 453?,if not can anyone recomend a russian type/part number?,cheers in advance.
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Re: Tek 575 Mod Lit Redone
Hi Bill,
Thanks for the info.
I'd like to add that anyone still using Acrobat 9 today will have to be mindful of the numerous security problems in that product.
It should not be used to open documents of unknown provenance.
To my knowledge, it is still possible to install a current version of the Reader in parallel and set that as the default program to open PDFs (or a third party PDF reader if you prefer).
I was also never happy with its OCR component for technical documents. I'm now using FineReader configured to additionally recognize Ohms, mu and similar symbols.
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You never know where Tek stuff will show up
Last weekend I saw an estate sale listing on CL that had a short, but interesting description and no photos.? It turned out that the owner's father had been a man of many interests and talents, and she just wanted to get rid of everything.? So, lots of woodworking things, a large, old Southbend lathe and other metal working tools, fishing, hunting, a half-finished sailboat hanging from the rafters.? An Eico 75Khz scope up high, just in reach. (It worked, but the last thing I need is one of them). Also found and Bell and Howell prototyping kit, but it used metal pins on a .5" spacing.? Then, digging through a box I found a bag of Tek ceramic terminal strips, half of which were unused.? In talking with the owner, she said that they had filled three dumpsters with "mostly junk", but that a lot of electronic parts and "large blue boxes with dials and switches" had also been tossed.? When I mentioned the Eico, she basically confirmed that they were oscilloscopes, but most "didn't look like they would work".
I wonder what had been thrown out?? On the drive home I had visions of NOS tunnel diodes and partial 570's.? I spent $30 and filled the minivan to the brim, so I won't complain, but thins one will haunt me for a while...
-Dave
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Photo 01 TEK 475 Shorted Tantalum C961 and Intermittend GND at HEX pillar_1.jpg updated
#photo-notice
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Thanx for your very detailed (and I think time consuming ;-) report.
¸é±ð²Ô¨¦
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Michael W. Lynch