Re: Tek 7904 HV transformer T1310 part 120-0742-00 insulation burning
On Fri, Oct 18, 2024 at 11:05 PM, Froggie the Gremlin wrote:
Dolph electrical varnish, heat cure
Do you mean Dolph's ... a vonRoll trademark?
They do produce impregnation 'resins' for transformer manufacture, and repair.
That doesn't seem... to me... to be something you can get at your local hardware store.
?
MG Chemicals sells
4228A ¨C Red Insulating Varnish
I think that is available, (Amazon etc.)
Contains a list of chemicals that may induce fear, and panic.... but otherwise okay by me.
?
But how are you going to impregnate the winding(s)?
Usually, you do that under a vacuum, where the air gets displaced by the 'varnish'
not the best idea if using high VOC resins.
?
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Re: Tektronix TDS754D - failing acquisition module tests
I have a 754D and a 784D.? I really like these scopes except for the display size. I occasionally will hook up a 13" to 15" color display and set on the edge of the bench while I am working.
?
If I remember right there are a bunch of mods that can be done with jumpers, caps and recalibration. You can turn a 754D into a 784D.? May try this one day but I have a good working 784D already.? You may want to look into the upgrades once you have gotten all the fixes done to your current scope.
--
T. Gerbic
Central California
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Re: Tek 7904 HV transformer T1310 part 120-0742-00 insulation burning
Thanks - I think you may be right - would be much easier to wind thus too! I think I found your description of layer with retrace Alan On Tue, 18 Feb 2025 at 17:47, Dave Wise via groups.io <d44617665@...> wrote:
To me that doesn't look like sections - the ridge is pitched. I think it's a foil shield with a spiral drain wire.
I only know older transformers, but every one of those was wound progressive-universal.
That doesn't mean that a rewind has to be the same, I did my 453 by hand using layer winding with retrace. It's documented in the TekScopes group.
Dave Wise
________________________________
From: [email protected] <[email protected]> on behalf of Alan Bain via groups.io <alan.bain@...>
Sent: Tuesday, February 18, 2025 7:33 AM
To: [email protected] <[email protected]>
Subject: Re: [TekScopes2] Tek 7904 HV transformer T1310 part 120-0742-00 insulation burning
Here's a photo of the innermost (high voltage winding). The drawing
just specified 544 turns of #38 AWG wire, but looking at the photo it
appears as if it might be sectionally wound with 11 sections. I've
only ever wound these on divided formers which this one clearly is
not.
Does anyone know any more?
Alan
On Sat, 19 Oct 2024 at 07:05, Froggie the Gremlin via groups.io
<jonpaul@...> wrote:
We used Dolph electrical varnish, heat cure.
The silocones are not reccomended for transformer impregnation as air voids can form.
The wdg lay is optimized if perfect lay, L>R rather then cris cross.
Jon
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Re: Tek 7904 HV transformer T1310 part 120-0742-00 insulation burning
To me that doesn't look like sections - the ridge is pitched.? I think it's a foil shield with a spiral drain wire.
I only know older transformers, but every one of those was wound progressive-universal.
That doesn't mean that a rewind has to be the same, I did my 453 by hand using layer winding with retrace.? It's documented in the TekScopes group.
Dave Wise
toggle quoted message
Show quoted text
Here's a photo of the innermost (high voltage winding).? The drawing
just specified 544 turns of #38 AWG wire, but looking at the photo it
appears as if it might be sectionally wound with 11 sections. I've
only ever wound these on divided formers which this one clearly is
not.
Does anyone know any more?
Alan
On Sat, 19 Oct 2024 at 07:05, Froggie the Gremlin via groups.io
<jonpaul@...> wrote:
>
> We used Dolph electrical varnish, heat cure.
>
> The silocones are not reccomended for transformer impregnation as air voids can form.
>
> The wdg lay is optimized if perfect lay, L>R rather then cris cross.
>
> Jon
>
>
>
>
>
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Re: Tek 7904 HV transformer T1310 part 120-0742-00 insulation burning
Here's a photo of the innermost (high voltage winding). The drawing just specified 544 turns of #38 AWG wire, but looking at the photo it appears as if it might be sectionally wound with 11 sections. I've only ever wound these on divided formers which this one clearly is not. Does anyone know any more? Alan On Sat, 19 Oct 2024 at 07:05, Froggie the Gremlin via groups.io <jonpaul@...> wrote:
We used Dolph electrical varnish, heat cure.
The silocones are not reccomended for transformer impregnation as air voids can form.
The wdg lay is optimized if perfect lay, L>R rather then cris cross.
Jon
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Re: Tektronix TDS754D - failing acquisition module tests
Hi,
I was having the memory error on my 754D, U206 and U208 were specified in the log in different test runs. I did initially replace U206 and U208 without success. All the 308pins on the QFP controller had good solder joints. While probing for solder bridges after installing the new chips, I managed to catch two consecutive pins shorted.
?
Turns out this short was NOT a solder bridge, it was a bad SRAM chip with the pins (25-26) internally shorted! Not any one already replaced. I had to remove 7 chips from the gang before finding the bad one.
?
-> Note that the 8 gang is split 4 on top side and 4 on bottom side.
?
It is logical that if two address or data bits are shorted (I did not check de spec), the diagnostic will fail on the first chip tested.
?
No more error! Yay. Now, I have to find a more affordable LCD solution than the one on ebay....
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Cheers.
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Re: JB Weld "Plastic Bonder" 24XX case repair
That is a very common problem with these scopes. The cause is assembling the case incorrectly. How do you do it incorrectly? Typically, by not making sure that the blue aluminum case body is settled into the RF gasket grove all the way around the front panel. When the case is correctly assembled, the back panel will be under very little force when the four screws are tight against the metal studs that pass thru the plastic to protect the back cover from the screw's pressure. The way I fix cracked backs is to fit all the pieces back together and use a drop of acrylic solvent weld applied in the closed cracks with a needle applicator. The repair is invisible for the most part. -Chuck Harris On Thu, 06 Feb 2025 15:42:22 -0800 "Don Brown, N3DEB" <dbawatsonville@...> wrote: Posted this in other Tek scope group, did not want to leave y'all out!
Note to group, my 2465B scope had cracked rear tan plastic cover. JB
Weld "Plastic Bonder" tan color is a 2 part polyurethane adhesive
with a great color match and adhesion. Should work other models I
would think.
I uploaded photo to Photos folder here:
/g/TekScopes/album?id=300551
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Re: JB Weld "Plastic Bonder" 24XX case repair
I have had very good results with "Plastic Bonder" also but must caution that I had the opposite experience with "Plastic Welder" by the same company.? Be careful not to confuse the two.
?
Chuck
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JB Weld "Plastic Bonder" 24XX case repair
Posted this in other Tek scope group, did not want to leave y'all out!
?
Note to group, my 2465B scope had cracked rear tan plastic cover. JB Weld "Plastic Bonder" tan color is a 2 part polyurethane adhesive with a great color match and adhesion. Should work other models I would think. I uploaded photo to Photos folder here: /g/TekScopes/album?id=300551
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Re: FS: Tektronix probes, calibration fixtures, gadgets
This stuff is sold or pending:
?
price for group: shipping
(1) HP 8495H attenuator (sma, programmable)
?
price for group: shipping
(1) Agilent 16752A logic probe cable set (4 pods)
?
price for group: ?200
(1) 013-0098-01 transistor curve tracer fixture
(3) 013-0124-00 integrated circuit curve tracer fixture
(2) 013-0101-00 TO-66 curve tracer fixture
?
price for group: shipping
(5) 015-0580-00 pocket signal generator
?
price for group: ?50
(1) 012-1372-00 tekprobe interface cable
?
thanks,
bill
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Re: 2467B Sweep test waveforms
Hm, let me try again with the attachments, now using the groups.io web interface. A sweep gate first - here I get a low level of +190 mV and a high level of 3.1V:
At waveform 35, half of the "low" time it seems to go below 0V? Again I see levels about 500mV above the expectation:
Here from the B sweep gate waveforms - I get something like 0V to 2.4V on both:
Now some schematics snippets:
(skipping the section with U975 inbetween)
?
- Michael
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2467B Sweep test waveforms
Hi all, I'm one more of those people who can't pass by when they see the shape and colors of something Tektronix. Now I'm working on a 2467B and while it seems to be working well, there was one thing I wanted to resolve before finishing my calibration efforts. It's a late model I think; some date codes are from 1995, the serial is B053790. I started measuring the test waveforms from the service manual (070- 6863-01) in the trigger, sweep, horizontal amp and Z-amp sections (reson below). What I am confused about is that several sweep gate and sweep waveforms initially look okay on my scope but I don't see the same levels. And looking at the schematics, the test waveforms don't make sense to me. Waveform 31, for example, is supposed to reach -0.2V. But I assume U700 outputs 0V or 3V on the SG# pin, and Q745 cannot pull it lower than GND. What does? CTO by charging the "** part of ECB" capacitor?! I normally work in the digital domain and I always struggle with these analog things. For the B trigger, waveform 38 is easy, it's just 0V or 3V on SG#. But then waveform 39 follows and quite unexpectedly drops down to - 0.5V. Again, the PNP transistor doesn't seem to explain that. These A and B "sweep gate not" signals are interconnected and also enter U985 and U975 (the "measurement PAL"). The latter seems to get pretty warm, but I see no obvious malfunction. I read the circuit description on page 3a-21 of the manual but it did not give me an answer. So any help making sense of these waveforms is greatly appreciated! As for the reason for looking into this, I had some difficulties doing the "high drive focus" and "writing rate threshold" adjustments on page 5-6 of the manual. Triggering seemed unstable, although this might be normal (the manual talks about a "flashing sinewave"). Later I noticed that at fast sweep times, something like 2 DIV of the trace seemed to be missing between the triggering edge and the start of the trace on the display. An explaination was given on the other list [1] about how this is expected behavior due to propagation delay in digital logic and I can actually see the triggering edge, thanks to the delay line. I'm attaching some screenshots/pages from the manual for the reader's convenience (or at least I'm trying). - Michael [1] /g/TekScopes/topic/11350057
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FS: Tektronix probes, calibration fixtures, gadgets
These are equipment accessories for which I no longer have the original test equipment, mostly from Tektronix, with a few from HP or Aglient.? Some notes:?
?
1. accessories with the notation "NOS" are unused, still in their original packages, including their probe leads and so on.
2. accessories with the notation "working" have been tested for basic functionality on a 350MHz oscilloscope.
3. accessories without the notation "working" are sold as-is because I don't have a way to currently test them.
4. oscilloscope probes do not come with grounds, probe clips, or other add-ons unless explicitly noted.
5. accessories are all in good mechanical condition. the older stuff has the usual knicks and scratches.
6. prices do not include shipping costs, which I will add to the purchasse price when I have your address.
7. accessories are grouped, with a price for the lot given. Sorry but I am not interested in breaking the lots up.?
8. acceptable payment methods are Zelle, check, USPS money order, and (reluctantly) Paypal family and friends. Checks and money orders must clear before shipping.
9. buy two groups and take a ten percent discount
10. buy it all and take a twenty percent discount
?
Shipping will be from Portland, Oregon and limited to domestic buyers. Given the current turmoil in the United States, customs and overseas shipping is a non-starter for now.
?
My contact information is on QRZ.com under my amateur radio call sign, K7WXW: ?https://www.qrz.com/db/k7wxw ?
?
Thanks,
Bill
?
TEKTRONIX ACCESSORIES
?
price for group: ?80
(4) 012-0747-00 and 020-720-00 logic analyzer probe test lead set (NOS) - in original bags with probe adapters, grounds, probe clip
(1) 012-0747-00 logic analyzer probe test lead set
(1) 020-720-00 probe adapters (NOS) - in original bags
?
price for group: shipping
(6) 015-0580-00 pocket signal generator
?
price for group: ?50
(1) 012-1372-00 tekprobe interface cable
?
price for group: ?50
(1) S-3A sampling head (SN B041187)
(2) 012-0130-00 sampling head interface cable
?
price for group: ?200
(1) 013-0098-01 transistor curve tracer fixture
(3) 013-0124-00 integrated circuit curve tracer fixture
(2) 013-0101-00 TO-66 curve tracer fixture
?
price for group: 100
(1) 067-0608-00 overdrive recovery calibration fixture
(1) 067-1341-00 risetime limiter
(1) 067-0554-00 tunnel diode pulser
(1) 067-0562-00 P6046 input adapter
(1) 067-0538-00 input RC normalizer
(2) 011-0081-00 termination/feedthrough
(1) 067-0569-00 ? ?sweep attenuator
(1) 015-0168-00 displacement transducer
(1) 067-0969-00 tape head alignment module
?
price for group: ?200
(5) P6122 100MHz probe (working)?
(2) P6105A 100Mhz probe (working)
(2) P6062B 100MHz probe (working)
(1) P6109B 100HMz probe, NOS (working)
?
price for group: ?180
(4) P6109 150MHz probe, one NOS (working)
(2) P6053B 200MHz probe (working)
(3) P6106 250MHz probe (working)
?
price for group: 225
(2) P6135A 150MHz differential probe (working, black tip, with ground cable)
?
price for group: 160
(2) P6134 300MHz probe (working)
(2) P6134 300MHz probe (working, no probe tip)
?
price for group: 60
(3) 119-1164-00 bias return
?
HP AND AGILENT ACCESSORIES
?
price for group: shipping
(1) HP 8495H attenuator (sma, programmable)
?
price for group: shipping
(1) Agilent 16752A logic probe cable set (4 pods)
?
price for group: shipping
54003A(2) HP 54003A probe pods
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Re: Tek 492 SA PSU removaal
Tom, many thanks for the info.
This analyzer is like a Chinese puzzle, 53 assemblies, huge 2 volume service manual.
Have read KE5FX, fine site.
Analyzer PS voltages , ripple are well in spec, working fine.
On 120V line, VDE caps unlikely to fail.
I will pass on the PS rework for now...
"If it ain't broke, don't fix it".
Jon
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Re: Tek 492 SA PSU removaal
I've replaced the RIFAs and the cooling fan in my 492AP.
You are right; the manual is not good in this respect. That reflects the, um, "ingenuity" the designers used to fit all the connectors and parts into the available space.
Basically it is a right royal pain in the backside, but I managed it. Having a front cover enables the 492 to be positioned vertically on the bench, which is a major advantage.
The passage of time has mercifully erased many of the details from my mind, but there's weirdly positioned small multipole connector on the side that is "just" pushed back a short distance (?into the carcase?) to release it. When you get a bit further in and are trying to split several subassemblies apart (?a30 from a30a57?), it is easy to remove irrelevant screws.
So my best advice is rather thin: use the manual as a guide, proceed slowly and carefully looking at the problem from all sides (literally!) several times. Then jiggle things. Rinse and repeat. Not for the fainthearted!
ke5fx has created a pdf containing his "Tektronix 49x/275x/279x-Series Spectrum Analyzer Service Notes"
On Sat, 25 Jan 2025 at 23:27, Froggie the Gremlin via <jonpaul= [email protected]> wrote: Hello again
?Have a working Tek SA 492, SN?B05? 1984 ,? ?2500 hrs.
to check power supply for RIFA caps,? lytic and tants, the.? PSU? remove procedure in manual is vague on the location of connectors before you pull it.
Any tips or diagrams ?? caps to replace or change ?
Your thoughts and advice appreciated?
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Hello again
Have a working Tek SA 492, SN?B05 1984 , 2500 hrs.
to check power supply for RIFA caps, lytic and tants, the. PSU remove procedure in manual is vague on the location of connectors before you pull it.
Any tips or diagrams ? caps to replace or change ?
Your thoughts and advice appreciated?
Many thanks
Jon
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Re: Help Needed- Distortion display using HP334 or equiv.
I remember the Sequerra 1. A tour de force. II¡¯m still using a Dynaco FM-5 SS tuner from the late 70¡¯s. Plus, I have a couple of the higher end Yamaha tuners that get more airtime these days.
Here¡¯s a video you may enjoy on the topic:
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Re: Help Needed- Distortion display using HP334 or equiv.
Here¡¯s a video you may enjoy on the topic:
https://youtu.be/EjV-sAW8Ylg?si=OS5NuiZatemu2AGM
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Re: Help Needed- Distortion display using HP334 or equiv.
My work with Dick and Sid the ex Marantz tube HiFi designers,
Enjoy
Jon
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Re: Help Needed- Distortion display using HP334 or equiv.
There's the HPWiki here: Be sure to the HP pix here: beautiful work Thanks again for the info - I¡¯ll go dredge for Tek & HP App notes -
another old favorite. Am familiar with w140 for Tek stuff. Need to
brush up on source for HP app notes. Agilent used to host them, but
not sure anymore.
Randy
Randy, Bill @ PEARL in BC
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bill K7WXW
Froggie the Gremlin
Bill Perkins