Re: My TDR Evaluation of the SG503 012-0482-00 Cable has been uploaded
Very timely: this weekend I picked up a Tek 1502B, and it came with a 012-0482-00 cable and a 011-0123-00 BNC 50ohm terminator. Apart from that I only have "generic" connectors and terminators, of variable quality.
Caveat: I don't understand the expected performance of the 1502B, and haven't calibrated it at all.
Having said that, the only significant difference from your report is the velocity factor. In order for the 1502B to show the cable's length as 3ft, I have to set the velocity factor to 0.67.
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On 29/04/19 01:19, Dennis Tillman W7PF wrote: I uploaded the results of my testing the SG503 012-0482-00 cable. In
addition I compared it to two other similar cables: a Tektronix 012-0057-00
50惟 cable, and a Pomona Electronics 50惟 cable.
It is located at:
/g/TekScopes/files/Evaluation%20of%20the%20Tektronix%20012-
0482-00%20cable%20for%20the%20SG503.pdf
Dennis Tillman W7PF
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Re: My TDR Evaluation of the SG503 012-0482-00 Cable has been uploaded
I麓m going to solder a 1m RG223 cable for my SG503 so this is interesting stuff for me.
Nice detailed piece of work Dennis, thanx!!
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Re: 475A with High +110 rail
Michael-
I also would check the eb voltages聽 of Q1496 and Q1497 make sure nothing strange and xstrs are operating in their proper regions.
I would then take a hard look at CR1489 ( protection ec junction for pass xstr), almost seems like it might be leaking badly or possibly shorted bypassing the regulation. ( I had one go bad in a different supply....took a 5kv hit). It appears you have eliminated most everything else.
those are my guesses with the info provided. Someone else may have more insight.
搁别苍茅别
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On 2019-04-28 10:00 p.m., Mlynch001 wrote: I have searched for a previous thread that was referred to in a post about a "high" 110 voltage rail on a 475 from back in 2012. I failed to find that post or any other applicable answer, perhaps I am not searching for the correct words? So I will ask for some help. I have a 475A with DM44 s/n B012228. After a thorough cleaning, I turned it on and find that for the most part it works great, no triggering issues, bright trace, all controls respond as expected, just dirty pots and switches. I supply various signals to the A and B channels and the scope displays a good trace with with amplitude matching the output of my signal generator, so calibration seems to be close enough for hobby work. The scope simply does not act as if there is anything wrong. For safety sake, I pulled the case and tested the various system voltages on the A9 interface voltage test points. I found everything to be spot on, except the +110 volt rail, Voltages as follows:
-15V = -14.998
-8V = -8.005
5V = 5.005
15V = 15.002
50V = 50.035
Unregulated 50V = 63.35
110V = 134.66
Line Voltage is 120V and the voltage calibrator on the transformer is set to the proper voltage. I pulled and tested Q1490, Q1494, Q1496 and Q1497. These all tested "good" with a transistor tester. I also replaced Q1490 and Q1494 with "Known Good" components, with no change noted in the +110V rail. I did not have exact replacements for Q1497 or Q1496, but they did both test good. I did go through to check and seat all the transistors that I could reach on all the boards. I checked the various resistors in LV +110 Supply regulator circuit (the ones I could reach) and found then to be very close to correct. I do not want to start un-soldering components without some idea of what to check next. I do not know if CR1489 has anything to do with the voltage regulation or not, but that component appears to be part of the +110 regulation system. Other than the "too high" +110 rail, the scope demonstrates no other issues, nothing smells "Hot" and no "magic smoke", The boards inside the scope are perfect, no signs of repairs, heat or damage. I just want to sort this out before I use the scope very much. Collector voltage on Q1497 is 134.5 and Q1496 at about 133.8. Almost everything agrees with the schematic EXCEPT that pesky +110V rail. Any ideas where to check next?
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Re: My TDR Evaluation of the SG503 012-0482-00 Cable has been uploaded
Those are interesting measurements Dennis. And particularly interesting that although the
Pomona/Belden the impedance is not 50 ohms, although the variation seems to be very low. And it will
be more than an order of magnitude cheaper than the double shield Tek cable
Craig
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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Dennis Tillman W7PF
Sent: 29 April 2019 01:19
To: [email protected]
Subject: [TekScopes] My TDR Evaluation of the SG503 012-0482-00 Cable has been uploaded
I uploaded the results of my testing the SG503 012-0482-00 cable. In addition I compared it to two
other similar cables: a Tektronix 012-0057-00 50� cable, and a Pomona Electronics 50� cable.
It is located at:
/g/TekScopes/files/Evaluation%20of%20the%20Tektronix%20012-
0482-00%20cable%20for%20the%20SG503.pdf
Dennis Tillman W7PF
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I have searched for a previous thread that was referred to in a post about a "high" 110 voltage rail on a 475 from back in 2012. I failed to find that post or any other applicable answer, perhaps I am not searching for the correct words? So I will ask for some help. I have a 475A with DM44 s/n B012228. After a thorough cleaning, I turned it on and find that for the most part it works great, no triggering issues, bright trace, all controls respond as expected, just dirty pots and switches. I supply various signals to the A and B channels and the scope displays a good trace with with amplitude matching the output of my signal generator, so calibration seems to be close enough for hobby work. The scope simply does not act as if there is anything wrong. For safety sake, I pulled the case and tested the various system voltages on the A9 interface voltage test points. I found everything to be spot on, except the +110 volt rail, Voltages as follows:
-15V = -14.998
-8V = -8.005
5V = 5.005
15V = 15.002
50V = 50.035
Unregulated 50V = 63.35
110V = 134.66
Line Voltage is 120V and the voltage calibrator on the transformer is set to the proper voltage. I pulled and tested Q1490, Q1494, Q1496 and Q1497. These all tested "good" with a transistor tester. I also replaced Q1490 and Q1494 with "Known Good" components, with no change noted in the +110V rail. I did not have exact replacements for Q1497 or Q1496, but they did both test good. I did go through to check and seat all the transistors that I could reach on all the boards. I checked the various resistors in LV +110 Supply regulator circuit (the ones I could reach) and found then to be very close to correct. I do not want to start un-soldering components without some idea of what to check next. I do not know if CR1489 has anything to do with the voltage regulation or not, but that component appears to be part of the +110 regulation system. Other than the "too high" +110 rail, the scope demonstrates no other issues, nothing smells "Hot" and no "magic smoke", The boards inside the scope are perfect, no signs of repairs, heat or damage. I just want to sort this out before I use the scope very much. Collector voltage on Q1497 is 134.5 and Q1496 at about 133.8. Almost everything agrees with the schematic EXCEPT that pesky +110V rail. Any ideas where to check next?
--
Michael Lynch
Dardanelle, AR
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Re: 2465B Parametric Freq Measurement Error
Is my Tektronix 2465 DMS using the same part number or do I need a
different one?
Where would I find more information how to perform the replacement?
Thanks.
Tony
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On Sun, Apr 28, 2019 at 8:43 PM Chuck Harris <cfharris@...> wrote: The parametric measurements use the trigger hybrid extensively,
and their performance is directly related to how well that hybrid
performs. Some are better than others.
-Chuck Harris
joe@... wrote:
After successfully calibrating my 2465B, it reports "All tests passed" on start up. The question marks are all gone! My issue is with the
parametric measurement of frequency. When I attempt to measure the
frequency of a sine wave at frequencies higher than 10 MHz, the scope
reports the frequency as 35.62 kHz. Any test frequency above 10 MHz gets
the exact same report, 35.62 kHz. Below 10 MHz, it reports various
incorrect values (i.e. a 4.89 MHz signal is reported as 6.35 MHz). At
about 500 kHz and lower frequencies, the scope reports the correct
frequency. I have replaced the PAL at U975 - no change. Any suggestions?
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Re: 2465B Parametric Freq Measurement Error
If I replace the trigger hybrid, do I have to do the whole calibration again? Joseph Suste
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Re: 2465B Parametric Freq Measurement Error
The parametric measurements use the trigger hybrid extensively,
and their performance is directly related to how well that hybrid
performs. Some are better than others.
-Chuck Harris
joe@... wrote:
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After successfully calibrating my 2465B, it reports "All tests passed" on start up. The question marks are all gone! My issue is with the parametric measurement of frequency. When I attempt to measure the frequency of a sine wave at frequencies higher than 10 MHz, the scope reports the frequency as 35.62 kHz. Any test frequency above 10 MHz gets the exact same report, 35.62 kHz. Below 10 MHz, it reports various incorrect values (i.e. a 4.89 MHz signal is reported as 6.35 MHz). At about 500 kHz and lower frequencies, the scope reports the correct frequency. I have replaced the PAL at U975 - no change. Any suggestions?
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Re: 2246 no display/odd behavior
Take note of where the grid bias R2719 is currently set by following the setup in the manual. You will do this in XY mode. See if you can get a dot displayed.
I agree that all the power supply rails look good.
The battery can be any 3.6 volt lithium cell with leads just for a test.
Good luck and regards
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2465B Parametric Freq Measurement Error
After successfully calibrating my 2465B, it reports "All tests passed" on start up. The question marks are all gone! My issue is with the parametric measurement of frequency. When I attempt to measure the frequency of a sine wave at frequencies higher than 10 MHz, the scope reports the frequency as 35.62 kHz. Any test frequency above 10 MHz gets the exact same report, 35.62 kHz. Below 10 MHz, it reports various incorrect values (i.e. a 4.89 MHz signal is reported as 6.35 MHz). At about 500 kHz and lower frequencies, the scope reports the correct frequency. I have replaced the PAL at U975 - no change. Any suggestions?
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My TDR Evaluation of the SG503 012-0482-00 Cable has been uploaded
I uploaded the results of my testing the SG503 012-0482-00 cable. In addition I compared it to two other similar cables: a Tektronix 012-0057-00 50惟 cable, and a Pomona Electronics 50惟 cable. It is located at: /g/TekScopes/files/Evaluation%20of%20the%20Tektronix%20012-0482-00%20cable%20for%20the%20SG503.pdf Dennis Tillman W7PF
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2246 no display/odd behavior
Ok. I've removed the battery - have a new one on order. When reassembling I found that J2208 was installed backwards initially. Corrected but no change in behavior. All further testing is done with the battery removed:
Exact voltages:
+131.34
+58.201
+15.052
+7.4913
+5.2186
-5.2245
-7.5541
-16.005
These all seem to be in spec.
I have a 6kV probe on order - should be here in a few days. I will probe the HV line at that point.
Beam finder does nothing. There is no display at all - no text, no beam. No change whether the front panel is powered up or not.
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Ok, compared the RG-58 Tektronix cable to an RG-400 I built of similar length.
At 200Mhz and 4Vpp (x1 amplitude) we have ....
The OEM Tektronix cable clocked in at 0.20 dBm low.
DIY RG-400 cable was only 0.01 dBm low!!
Now B4 you guys roast me over the Boonton 4210 microwattmeter with the 4210-4B sensor....
I make no claims, infer from the results what you will (expect 1.5% accuracy from the Boonton).
But...I feel pleased that the SG 503 combined with a RG-400 cable and the Boonton show what could be a nearly perfect output.
I must mention that I recently serviced the SG 503 using liquid de-oxit on the rotary frequency selector contacts and polished the brass nut and seat contact point on the variable tuning capacitor.
~A
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Re: 2246 no display/odd behavior
How can you edit a post on this system?
Anyway-
Have you replaced the battery yet? Should do that first and reboot the scope several times to get the ram initialized.
Pay attention to the adjustments section, especially the power supply and beam (grid bias) adjustments.
What are the _exact_ low voltage measurements?
The ripples shown on your pictures all look good.
Can you measure the -2.7 kV line safely? That can be accessed by looking at the cathode or filaments on the CRT.
Does the Beam finder button do anything?
Regards
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2246 no display/odd behavior
Ok so some updates:
I haven't found any previous posts that address my issues.
All voltages on the low side are in spec. Looking back at the ripple measurements in my first post I think they are all OK but a second set of eyes would be helpful. The p-p measurements seem high but there are very few points. The bulk of the points seem within the specs but there's some pronounced waveforms there that I don't know about being allowable.
I checked the ESR for all the electros on the power supply board - everything looks good (I used the Blue meter and tested in-situ).
Under the board I found a broken (lifted?) trace between C2244 and R2231. See here: I ran a jumper and re-assembled and no change in behavior. Still not display apart from a brief flash at power off and still the off behavior from the front LEDs where they don't power on unless I fiddle with the buttons.
There is a RIFA cap C2217 that looks a bit rough but not blown. I'm open to further suggestions or testing approaches. Still not sure if the two problems may be related or which I should focus on first. FWIW I can now get that PSU in and out in about 10 minutes flat... practice :D
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Re: Powering up a 577 for the first time
The 577 used one of the Tek custom potted SMPS transformers if my memory is correct. Next to a tube failure, that is your biggest worry.
I agree with others.
Clean, repair power cord, fuse, power, debug any failure.
There are quite a few threads here on fixing a577.
Keep us up to date.
Sent from kjo iPhone
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Re: Powering up a 577 for the first time
I think a good visual inspection followed by the use of an ohm meter would be my first plan. Then repair the cord and install the correct fuse. If you have an ESR meter, check the bulk capacitors and replace as necessary.
Power it up directly and measure the power rails next. I usually follow the performance section of the service manual as it will show you what works.
Calibration would be your next step and lead you to any troubleshooting that might still be needed.
Good luck and nice find with the cover still there.
Regards
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On 4/27/2019 6:35 PM, groups@... wrote: All,
While I was searching eBay for a transistor adaptor for my 576, I came across a parts 577 in good condition with both the adaptor and an original safety cover for a low price... and ended up snagging it, too.
It was advertised as not powering up - and on closer inspection, the power cable's strain relief is loose, and there's no fuse present. I can obviously fix both, but I'm wary of powering it up given that perhaps there's a reason the fuse is absent (although I'm comfortable checking rail voltages with suitable precautions once it's up). Any advice? Would a variac help?
Thanks,
Neil
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Re: Powering up a 577 for the first time
If you use the correct fuse then the fuse will protect the equipment. If the fuse blows then you need to go into troubleshooting mode.
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On April 27, 2019 4:35:59 PM MDT, groups@... wrote: All,
While I was searching eBay for a transistor adaptor for my 576, I came
across a parts 577 in good condition with both the adaptor and an
original safety cover for a low price... and ended up snagging it, too.
It was advertised as not powering up - and on closer inspection, the
power cable's strain relief is loose, and there's no fuse present. I
can obviously fix both, but I'm wary of powering it up given that
perhaps there's a reason the fuse is absent (although I'm comfortable
checking rail voltages with suitable precautions once it's up). Any
advice? Would a variac help?
Thanks,
Neil
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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Re: Wanted: Earth leads with croc-clip for P6139A
I'm still wanting these if anyone can help.
Thanks
David
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of David C. Partridge Sent: 04 April 2019 18:55 To: [email protected]Subject: Re: [TekScopes] Wanted: Earth leads with croc-clip for P6139A Yes I'm in the UK. You may be able to send them quite cheaply (about ten dollars for up to 8oz) if you use a pre-paid padded envelope 1st class international mailer. Anyone closer? David -----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Stephen Hanselman Sent: 04 April 2019 17:34 To: [email protected]Subject: Re: [TekScopes] Wanted: Earth leads with croc-clip for P6139A OK, I do have a bag of 6 inch long "ring" mount style and have verified them on my P6139. They have an alligator clip on the end. Are you in the UK? Shipping will be more than the cost of the clips I'm afraid steve -----Original Message----- From: [email protected] < [email protected]> On Behalf Of Stephen Hanselman Sent: Thursday, April 4, 2019 8:35 AM To: [email protected]Subject: Re: [TekScopes] Wanted: Earth leads with croc-clip for P6139A I鈥檓 pretty sure I have a bundle of those I鈥檒l check when I get to the office Regards, Stephen Hanselman Datagate Systems, LLC 3107 North Deer Run Road #24 Carson City, Nevada, 89701 (775) 882-5117 office (775) 720-6020 mobile s.hanselman@... www.datagatesystems.com a Service Disabled, Veteran Owned Small Business DISCLAIMER: This e-mail and any attachments are intended only for use by the addressee(s) named herein and may contain legally privileged and/or proprietary information. If you are not the intended recipient, any dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this e-mail in error, please immediately notify me and permanently delete the original and all copies and printouts of this e-mail and any attachments. On Apr 4, 2019, at 06:22, David C. Partridge <david.partridge@...> wrote:
No, those are the older ones the ones I'm looking for look like this:
<>
Dave
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Colin Herbert via Groups.Io
Sent: 04 April 2019 13:13
To: [email protected]
Subject: Re: [TekScopes] Wanted: Earth leads with croc-clip for P6139A
Would these do?
eads-w
ith-Alligator-Clip-Tektronix-HP/222659358233?ssPageName=STRK%3AMEBIDX%
3AIT&_
trksid=p2060353.m1438.l2649
They have a length of 7 inches (17.5 cm). I bought some a while ago
and they are fine, if possibly not genuine Tek. He also has the "witches hat"
grabbers for P6139, etc. probes. Be careful, though, as while he will
offer combined postage, eBay doesn't seem to go along with that. It
took me some time to get combined postage when I bought three items
from him. Of course, this might have improved, now.
Colin.
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of David C.
Partridge
Sent: 04 April 2019 12:03
To: TekScopes
Subject: [TekScopes] Wanted: Earth leads with croc-clip for P6139A
I'm looking for the earth leads with crocodile clip to fit the P6139A
and similar probes.
I have the ones that connect to mini-grabbers, but lack the croc-clip
versions.
Does anyone have these available?
Cheers, David
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Mlynch001
Ancel
David C. Partridge