Date   

Re: 465B Horizontal Trace Issues - Help requested

Jean-Paul
 

Hello again:

The TEK trimpots seldom fail entirely.

They are almost always corroded on contact or element, internally,

Spray high quality contact cleaner and exercising the trimpot end to end several times, fixes the pot 98% of the time.

Afterwards just recalibrate.

Much easier then replacing the pot!

Jon


Re: Ot 345kv substation walkthrough

John Williams
 

Greg recall in 2014 at KOMO in Seattle when their news helicopter lifted off the roof and crashed. Same story I suspect.

https://komonews.com/news/local/2-killed-as-komo-news-helicopter-crashes-near-space-needle-11-20-2015


Re: C1001/2 vid' cams for the 11301/2

Bill Perkins
 

Thx for all that, it was in any case a project well down my already too long list.

The pix I want will come from a benched R7603 and a little tripod between the benchtop and my Canon EOS 30D ought to pretty much get me where I want to go.

That said though, I -was- curious.


Re: C1001/2 vid' cams for the 11301/2

Charlie Conger
 

That exactly what it is a video camera and frame grabber card. It has the ability to monitor the waveform for changes and then capture those. It was a way to get the performance of a high speed digitizer on the cheap( as long as you have good high speed analog scope). it was a follow on to earlier high speed digitizers that had internal scan converts that did much the same thing. However, it is difficult to set up and requires fiddling. I do not recommend you messing with it unless you are just curious.


Re: 465B Horizontal Trace Issues - Help requested

Tom Lee
 

Terrific hanging in there, Gary. There’s no problem leaving a fixed resistor in there until you get a replacement pot.

Now go celebrate!

—Cheers,
Tom

Sent from my iThing, so please forgive typos and brevity.

On Oct 1, 2020, at 6:23 PM, gary@pincus4.com wrote:

Eureka!

I just executed the idea of bypassing the 1X pot (1k ohm) - first with a jumper I had handy that I use to discharge capacitors (a 5W 1K resistor in a wire between two minigrabber probes). That brought the resistance in line with what it should be reading through the pot. Then I replaced the resistor with my Heathkit IN-3117 Decade resistance box. Even set to zero ohms, when i turned on the scope the trace was stable and only slightly compressed. Changing the resistance on the box allowed me to set the trace to any level of compression including no compression at all. I have it exactly where it should be - right to the edges of the grid (390 ohms is just about perfect). When I unplug one of the leads from the decade box, the trace immediately collapses, plug it back in and trace is perfect. Shailendra you suggested that the problem may be the pot - good call.

I do believe this confirms the 1X pot is the culprit. Shailendra you suggested that the problem may be the pot - good call. Since i have a 390 ohm 1/2W resistor and not the the pot, I think i will put in the resistor and run it for a while to see if everything else is working properly. Then when I have collected all necessary parts (pots, tants, electrolytics), and increased my skill level, take it apart, clean it and preemptively replace the usual suspects. Since a pot is just a variable resistor I can't think of any reason not to leave a fixed resistor soldered in place for a month or two. Other than this being a "kluge" repair to a precision instrument any reason not to? But if anyone can think of an electronic reason, please let me know.

I feel like the lawnmower mechanic that just "fixed" the Ferrari with a hair pin.

I will put together a BOM for pots, tants, and lytics and run it by this group.

Thanks for all the help and encouragement.

Gary





Re: 465B Horizontal Trace Issues - Help requested

 

Nice work Gary. Thanks for sharing your repair.

On 10/1/2020 9:23 PM, gary@pincus4.com wrote:
Eureka!

I just executed the idea of bypassing the 1X pot (1k ohm) - first with a jumper I had handy that I use to discharge capacitors (a 5W 1K resistor in a wire between two minigrabber probes). That brought the resistance in line with what it should be reading through the pot. Then I replaced the resistor with my Heathkit IN-3117 Decade resistance box. Even set to zero ohms, when i turned on the scope the trace was stable and only slightly compressed. Changing the resistance on the box allowed me to set the trace to any level of compression including no compression at all. I have it exactly where it should be - right to the edges of the grid (390 ohms is just about perfect). When I unplug one of the leads from the decade box, the trace immediately collapses, plug it back in and trace is perfect. Shailendra you suggested that the problem may be the pot - good call.

I do believe this confirms the 1X pot is the culprit. Shailendra you suggested that the problem may be the pot - good call. Since i have a 390 ohm 1/2W resistor and not the the pot, I think i will put in the resistor and run it for a while to see if everything else is working properly. Then when I have collected all necessary parts (pots, tants, electrolytics), and increased my skill level, take it apart, clean it and preemptively replace the usual suspects. Since a pot is just a variable resistor I can't think of any reason not to leave a fixed resistor soldered in place for a month or two. Other than this being a "kluge" repair to a precision instrument any reason not to? But if anyone can think of an electronic reason, please let me know.

I feel like the lawnmower mechanic that just "fixed" the Ferrari with a hair pin.

I will put together a BOM for pots, tants, and lytics and run it by this group.

Thanks for all the help and encouragement.

Gary



--
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https://www.avast.com/antivirus


Re: 2235 Repair having no power

satbeginner
 

Hi,

Since it (the transformer) was broken anyway, I opened it up to see if a rewind of (most likely) the HV winding would be possible.
First of all, it was completely potted, so already quite difficult to open up.

And, on top of that, the HV winding in this version of the transformer turned out to be physically in between the pins 12,13,14,15,16 and pins 17,18,19 winding.

So no "easy" access to the HV winding without destroying another winding first.

Here are some pictures I took: https://groups.io/g/TekScopes/album?id=254000

So, still looking for a TekTronix 22xx T948 transformer... :-)

Saludos from Spain,

Leo


Re: T912 F782

Mitchel Rought <mitchelrought@...>
 

I believe it is a pico fuse, it's approx. the size of a 1/4 resistor with four bands, red,green,red,red and the last band is twice the width of the other bands
I'm not used to pico fuses being rated this way, used to them listed by amp rating
the bands equal 1500 which might mean 1500Ma. or 1.5A?
I put a picture in the photo album if you want to look at it
thanks


Re: T912 F782

Michael W. Lynch
 

Mitchel,

I did not think about this when I spoke earlier. I have a T922 (non-storage) so it is likely very different inside. I will take a look and see if there are any such fuses inside the T922.

--
Michael Lynch
Dardanelle, AR


Re: T912 F782

tekscopegroup@...
 

Not sure if I might be wrong, and I am not at all familiar with the T912, but did you mean that you see a small (like 1/4W) resistor and a spring inside a regular glass fuse? (like in a 3AG, etc). If so I have seen these before, and the resistor I assume is part of the fuse to help it open quicker by generating heat that helps to melt the bond so the spring will retract the fuse link and open the circuit. If so, I would just replace the fuse with regular fast blow of the same specs that you indicated earlier (125V 1.5A). Not sure these fuses with the resistor and spring inside are still being manufactured. Anyway just an idea.


Re: C1001/2 vid' cams for the 11301/2

Brian
 

Hi Bill , Imagenation are the guys that produced the cards I have , CX100 is the ISA card I have used and PXC200 is the PCI card , now replaced by the PXC200A . The software drivers etc are all still there on the website , I just checked  . They go all the way to providing code examples if you want to write your own s/w .I got my cards from Ebay so they cost nowhere near the prices shown on the site .
I'm not sure where I got the connection details for the C1001/2 from , I suspect that I went inside and did some circuit tracing , I had the distinct impression that the camera's were made by Mitsubishi at the time but I may have been wrong .
Brian

On Thursday, 1 October 2020, 23:50:28 BST, Bill Perkins <sales@pearl-hifi.com> wrote:

    Brian wrote:
  Hi Bill , I have several of these video camera's but not the Tek frame grabber or software . I have a Cortex frame grabber which works very well and some Cortex s/w available on their website some years ago - not sure about now though . The card I am using is an ISA card so it needs an old PC, there is a PCI version of the card which might be easily found and the s/w for that was also on the website. The cards have a 9pin 'D' type connector on the bracket which allows video input and also a trigger for grabbing a frame plus a 12v output which can power the C1001/2
I have also used the cameras with a cheap USB stick used for surveillance systems and also similar ones used in video to DVD applications without much trouble. I had a great time showing my 7104 screen on a 15 inch laptop screen . There is a downside using the cameras though, whatever you do it's not much good capturing any single shot waveforms
I hope this helps a little
Brian
    Yes, it does. Thx.
    Any chance for a few links, save me digging high and low ?
I'd want the PCI version of any card. ISA is just -so-last century  :-)

    Not one to be lazy, I did some digging and found this halfway likely
looking site:

    http://www.imagenation.com/imagena/default.html

but I don't know what I'm after.

    I'm planning to pick up a Tek 79364, a 500MHz storage unit*  so fast
one-shots won't be a problem and I work in audio so all that's sort of a
'who-cares' anyway.

    Thx,
    Bill
   
    * Yeah Walt, I'm still in; just delayed. My daughter bought the house
she wanted so I'll be out to see you real soon.


Re: T912 F782

Mitchel Rought <mitchelrought@...>
 

Michael
these fuses are not on my prints or parts list either
F782 is in the circuit for the flood gun heaters using U784 and is in front of CR783 located on the low voltage power supply board
thanks


Re: 465B Horizontal Trace Issues - Help requested

Jean-Paul
 

Hello BRAVO for your effort, the 465/475/B were my main scopes in 1970s, are a great advance over the 453/454/485. (At my first job, 1968 used 454)
Brings back memories!

Tants were used everywhere at that epoch, if the current is not limited and used near rated V they do fail shorted or blow open.

The 2" service manual is a classic and highly recommend to DL the PDF version for your serial number range.

This electronic dinosaur much prefers the original bound TEK to the PDF. Look on fleabay.

Qservice in Greece, has for sale very fine reproductions.

Finally, consider to recap the PSU, the lytics dry out and seals fail, also check the fan bearings.

Many threads on recapping the 465/475/B.

Bon chance!

Jon


Re: 465B Horizontal Trace Issues - Help requested

@Sabrefencer
 

Eureka!

I just executed the idea of bypassing the 1X pot (1k ohm) - first with a jumper I had handy that I use to discharge capacitors (a 5W 1K resistor in a wire between two minigrabber probes). That brought the resistance in line with what it should be reading through the pot. Then I replaced the resistor with my Heathkit IN-3117 Decade resistance box. Even set to zero ohms, when i turned on the scope the trace was stable and only slightly compressed. Changing the resistance on the box allowed me to set the trace to any level of compression including no compression at all. I have it exactly where it should be - right to the edges of the grid (390 ohms is just about perfect). When I unplug one of the leads from the decade box, the trace immediately collapses, plug it back in and trace is perfect. Shailendra you suggested that the problem may be the pot - good call.

I do believe this confirms the 1X pot is the culprit. Shailendra you suggested that the problem may be the pot - good call. Since i have a 390 ohm 1/2W resistor and not the the pot, I think i will put in the resistor and run it for a while to see if everything else is working properly. Then when I have collected all necessary parts (pots, tants, electrolytics), and increased my skill level, take it apart, clean it and preemptively replace the usual suspects. Since a pot is just a variable resistor I can't think of any reason not to leave a fixed resistor soldered in place for a month or two. Other than this being a "kluge" repair to a precision instrument any reason not to? But if anyone can think of an electronic reason, please let me know.

I feel like the lawnmower mechanic that just "fixed" the Ferrari with a hair pin.

I will put together a BOM for pots, tants, and lytics and run it by this group.

Thanks for all the help and encouragement.

Gary


Re: 465B Horizontal Trace Issues - Help requested

Harvey White
 

That seems to indicate that the horizontal amplifier, in the x10 position, can swing enough to give you proper deflection.

This suggests that the X1 pot and the components (and perhaps switches) are faulty.

IIRC, the X1 is the default, and the X10 is switched in (and less resistance), IIRC, this is an emitter coupled difrerential amplifier, and the resistor coupling the two emitters together determines stage gain.  Switching in an X10 pot (and adjusting it properly) gives you the additional gain.

Harvey

On 10/1/2020 7:53 PM, gary@pincus4.com wrote:
Yes, in the x10 position the trace does indeed seem uncompressed. I can find the "whole" trace by moving horizontal position, i even counted # of square waves to verify.





Re: 465B Horizontal Trace Issues - Help requested

@Sabrefencer
 

Yes, in the x10 position the trace does indeed seem uncompressed. I can find the "whole" trace by moving horizontal position, i even counted # of square waves to verify.


Re: 465B Horizontal Trace Issues - Help requested

@Sabrefencer
 

Tom,

Before my last post, I photographed (as a method of marking) the x1, and x10 pots and sprayed a small amount of Deoxit under the "dial" - the pot looks like it may be sealed, so I have no idea if it penetrated, but what the heck. I worked these pots back and forth many times with the power off, and even with scope operating, but no impact on collapsed trace. I have returned them to their original position. I tried to measure the resistance across the pot and nearby resistors, but this section of the circuit has parallel paths, with other resistors, so that may be difficult. I do not see a way to remove the pot without accessing the dark side of the A4 board, which requires disassembly. Is there a way to bypass or "jump out" the pot, either with a wire or a resistor (or even by resistor decade box - which is giant discrete pot)? In the meantime I am searching Mouser for a replacement pot.

You mention bias voltages in the stage, I do not know where to check that.

Thanks Gary


Re: C1001/2 vid' cams for the 11301/2

Bill Perkins
 

Brian wrote:
Hi Bill , I have several of these video camera's but not the Tek frame grabber or software . I have a Cortex frame grabber which works very well and some Cortex s/w available on their website some years ago - not sure about now though . The card I am using is an ISA card so it needs an old PC, there is a PCI version of the card which might be easily found and the s/w for that was also on the website. The cards have a 9pin 'D' type connector on the bracket which allows video input and also a trigger for grabbing a frame plus a 12v output which can power the C1001/2
I have also used the cameras with a cheap USB stick used for surveillance systems and also similar ones used in video to DVD applications without much trouble. I had a great time showing my 7104 screen on a 15 inch laptop screen . There is a downside using the cameras though, whatever you do it's not much good capturing any single shot waveforms
I hope this helps a little
Brian
Yes, it does. Thx.
Any chance for a few links, save me digging high and low ?
I'd want the PCI version of any card. ISA is just -so-last century :-)

Not one to be lazy, I did some digging and found this halfway likely looking site:

http://www.imagenation.com/imagena/default.html

but I don't know what I'm after.

I'm planning to pick up a Tek 79364, a 500MHz storage unit* so fast one-shots won't be a problem and I work in audio so all that's sort of a 'who-cares' anyway.

Thx,
Bill

* Yeah Walt, I'm still in; just delayed. My daughter bought the house she wanted so I'll be out to see you real soon.


Re: Ot 345kv substation walkthrough

Greg Muir
 

It only takes a little wind gust to throw things out of whack. And nicking your tail rotor is not good either.

When working on a contract with Denver Police many years ago had a chopper take off from a helipad next to the police building in the center of town. He was just barely gaining altitude when a little wind gust came around the corner of the nearby building spinning him around and catching the tail rotor on a nearby structure. He set down rather fast and awkward missing everything else. The good side was that he walked away from it.

Greg


Re: C1001/2 vid' cams for the 11301/2

Brian
 

Hi Bill , I have several of these video camera's but not the Tek frame grabber or software . I have a Cortex frame grabber which works very well and some Cortex s/w available on their website some years ago - not sure about now though . The card I am using is an ISA card so it needs an old Pc, there is a PCI version of the card which might be easily found and the s/w for that was also on the website .The cards have a 9pin 'D' type connector on the bracket which allows video input and also a trigger for grabbing a frame plus a 12v output which can power the C1001/2
I have also used the camera's with a cheap USB stick used for surveilance systems and also similar ones used in video to DVD applications with out much trouble . I had a great time showing my 7104 screen on a 15 inch laptop screen .There is a downside using the camera's though , whatever you do its not much good capturing any single shot waveforms
I hope this helps a little 
Brian

On Thursday, 1 October 2020, 22:37:28 BST, Bill Perkins <sales@pearl-hifi.com> wrote:

    Anyone have any experience with these; the frame grabber board and the
software are a complete mystery to me.

    TIA for any help/admonition.

    Bill

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