Re: You never know where Tek stuff will show up
This one isn¡¯t too bad. I had a friend that was ex - Motorola technician and had very good contacts in the company¡¯s technical end for a lot of years. I could not contact him for several months. I finally got in contact with a mutual friend that lived nearby. He told me that our friend had died. He found out about it a week after the event and his family was cleaning out the house so they could sell it. They filled 3 ea. 20 cu. yd. dumpsters with the ¡°useless¡± electronic test equipment, before he found out and stopped them. Our friend had a house filled with HP test equipment to the point that he had narrow walkways though the house except in the kitchen and his bedroom (the large house had 4 bedrooms and a full basement). There were multiple HP 141T SA systems, HP 8340 systems, a complete 8510C NA system with all possible interfaces and all possible Cal Kits, and all possible Ver Kits., plus any other generator you could think of from that era (30 yrs. ago) - I would guesstimate they tossed $200,000 worth of ETE in the dumpsters. Luckily they had not discovered the warehouse he was renting - floor to ceiling racks 30 ft. high, 3 ft. aisles, filling a 60 ft. x 120 ft. area. The mutual friend volunteered to sell off the warehouse contents for the family. I suspect that that sale resulted in an additional $150,000 to my late friend¡¯s estate.
The pity was I had found a buyer for the used 8510C for about $30,000 (original purchase price from HP $250,000+).
Don Bitters
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its odd,i had to view the mil manual in my browser,it wouldnt download,so i chose to select open with acrobat,did that then saved the file as and it worked,never had that before!
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No, they do not always have such a label. I have a 465 that has a 1xxxxxx serial # and no other evidence of its Guernsey origin. This is the purpose of TEK using their system of serial number prefixes to designate the plant that produced the instrument. Sometimes there is a label, sometimes not. As far as the military manual not downloading, I am having no such problem at the moment. Perhaps a local network issue?
--
Michael Lynch
Dardanelle, AR
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Re: AA5001 Mid-Repair Readings
To wrap up this subject, I do have my AA5001 back together and it does seem to be working very well. One or two of the reed relays might have started off a little scratchy, but when I tested them out of circuit, they were just fine. The primary problem appeared to be the one blown lamp in the low-level signal path (DS3050 or DS3060 on A14). Although they are supposed to come into use only on the lowest four voltage ranges, the open lamp must have also affected the auto-ranging and hunting process of the THD function. The only other issue was a missing decimal point on the display, which was cured by exercising / cleaning the J1050 board to board connection between the GPIB board and the logic board.
I thought I would share my findings for the incandescent lamps. Although I could not find a direct replacement, I did find a comparable lamp that has a base on it. It was relatively easy to remove the lamp base, freeing up the loose leads, so they could be installed just like the originals.
If anyone needs to perform a similar replacement, the Mouser part number is 560-120PSB. by heating each side of the lamp base with a soldering iron, the solder, the rubber tip, and adhesive give way, and you are left with the bare leads. The flying leads are not long enough to solder through the board, so short small-gauge wire works as a suitable extension. It is a little work to get the new bulb under the little rubber hold-downs, but it does work.
The new lamps are the same 120V 0.025A rating as the originals. My one working lamp measured 538 ohms, cold. The six replacements I received ranged from 548 ohms to 598 ohms. I am not terribly concerned about this difference, since I assume that any affect could be calibrated out (also, the remaining original might even be partially damaged from whatever signal blew the other one). I ended up replacing both lamps with two new ones that were more closely matched. At this point, low level measurements are within 0.5% of my primary RMS meter, so I am not going to tweak anything.
Thanks for your responses. Also, I appreciated the video links- I enjoyed them (of course!).
Brian
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i mean the military manual.
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well the manual wont download,keeps saying network error! dont all the gurnsey scope have that writen on them?,this doesent.
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Paul,
R471 is 4700 ohms and R675 is 4300 ohms. These are connected to the cathodes of the tunnel diodes. The schematic I used shows the Nuvistors. I do have one that has the FETs instead of the Nuvistors. See if yours has these resistors. Each resistor goes through a 47 ohm to the base of the transistors. The schematic for higher numbers was helpful from Michael. I will keep a copy of that for mine. Since your resistors you mentioned, 300 ohms, are close to the limit of tolerance, you can change them if you want. My post was not intended to confuse anyone. Apologies to anyone I confused.
Conversion to FET from Nuvistor I had a post about a couple of months ago. I did this in a 454. The same thing can be done in a 453.
The 5642 rectifiers can be replaced with a 2CL2H or 2CL2J.
Mark
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On Fri, Nov 19, 2021 at 09:58 PM, Albert Otten wrote:
The honor is for you Raymond!
I hope that's at least a bit tongue-in-cheek, Albert! Still, I do enjoy a bit of "told you so!" at times, just as much as I dislike missing something. I have to admit that my message was a bit terse but guess where my idea came from... Raymond
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The manual I downloaded shows "672" in the lower-right-hand corner of the first page. I presume that's the first edition and dated June, 1972.
Thanks for that update. It does clarify things a lot.
Thanks,
Barry - N4BUQ
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----- Original Message ----- From: "Albert Otten" <aodiversen@...>
To: "tekscopes" <[email protected]>
Sent: Friday, November 19, 2021 3:41:29 PM
Subject: Re: [TekScopes] 7704A - Grid Bias Hi Barry,
I saw now that the NOTE I mentioned is present in my Op. manual page 1-9 (Rev.
B, MAY, 1977) but not yet in the pdf I downloaded.
The Note says
".... The higher (further cw) the A INTEN control, the smaller the contrast
between the intensified and non-intensified portions of the trace. ..."
Albert
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Hi Barry,
I saw now that the NOTE I mentioned is present in my Op. manual page 1-9 (Rev. B, MAY, 1977) but not yet in the pdf I downloaded.
The Note says
".... The higher (further cw) the A INTEN control, the smaller the contrast between the intensified and non-intensified portions of the trace. ..."
Albert
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Hi Raymond,
When you asked that question in that post, I was thinking you were wanting to make sure that I knew that those control affect the brightness. I was unaware, though, that those should be set quite the way they should be. I have been relying on the Service Manual for documentation but I see now that the Operator's Manual is very important as well and have downloaded that. Hopefully that will reduce the number of "operator error" questions I have going forward.
I'm still not seeing, though, in the Operator's Manual (Manual #070-1402-00) where it states how to properly set the individual intensity controls to properly display a highlighted trace. The section titled "Intensity Controls" on path 1-9 discusses those controls but in a somewhat generic fashion. Perhaps I'm overlooking something.
Thanks,
Barry - N4BUQ
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----- Original Message ----- From: "Raymond Domp Frank" <hewpatek@...>
To: "tekscopes" <[email protected]>
Sent: Friday, November 19, 2021 2:48:39 PM
Subject: Re: [TekScopes] 7704A - Grid Bias On Fri, Nov 19, 2021 at 09:19 PM, n4buq wrote:
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?
If this is confirmed, it does look like operator error, doesn't it, as I
suggested in my message #188002 on November 14th? It's not two completely
independent controls, so perhaps a bit counterintuitive.
Raymond
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The honor is for you Raymond!
Albert
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On Fri, Nov 19, 2021 at 09:19 PM, n4buq wrote:
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?
If this is confirmed, it does look like operator error, doesn't it, as I suggested in my message #188002 on November 14th? It's not two completely independent controls, so perhaps a bit counterintuitive. Raymond
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Hi Barry,
I read the separate Operators manual now (too late of course) and found the special NOTE at page 1-9, discussing exactly this usage of A INTEN. There are other examples in that manual as well but those are more obvious.
Albert
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Re: You never know where Tek stuff will show up
On Fri, Nov 19, 2021 at 01:24 AM, Dave Seiter wrote: Last weekend I saw an estate sale listing... she said that they had filled three dumpsters with "mostly junk..."
Hauled to the tip... or curb-grabbed by 'recyclers' (a.k.a. garbage pickers) and sold ad scrap to pay for tonight's case of beer. That's what happens, more often than we know about. So I always tell technical hoarders ... your 'gold' is just so much garbage... after your gone. But, they never heed it. Roy Thistle
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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
toggle quoted message
Show quoted text
----- 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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Mlynch001
Brian Nordlund, AC7QE
Raymond Domp Frank
Michael W. Lynch