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Re: Horizontal jitter on 11801

 

Hi, Reg.Many moons ago I used an HP 54120 scope, similar to the Tek 11800 series.? Jitter crept in, and turned out to be the delay line was set for many nanoseconds.? When we finally set it back to minimum, the jitter went away.Then I went to a different companyand bought a Tek CSA803.? Never saw the problem with it.I liked the modular design of the Tek scope better, but really one wouldn't go wrong with either.? Rather like choosing between a Cadillac and a Lincoln!Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: "Reginald Beardsley via Groups.Io" <pulaskite@...> Date: 8/22/19 5:10 PM (GMT-08:00) To: [email protected], [email protected] Subject: [TekScopes] Horizontal jitter on 11801 My 11801 has developed a horizontal jitter.? Does anyone have any info about what I'm likely to? need to replace?? Or any source of component level information about the horizontal section?I've got the 11801 service manual, such as it is, but it's not a lot of help for diagnosis.? So unless someone has been there I'm probably best off just going through recapping the video section.thanks,Reg
Looking for Tek 2712 spectrum analyzer parts.

 

I know this may be a long shot but I am looking for an N connector and coax
assembly for a 2712. Also if someone has a good condition plastic end
panel for the back and the feet I'm looking for that also. Most important
thing is definitely the n connector. One side of the center pin is
missing. before I go to the trouble of a recalibration I would like to
have a good female N connector.


Thanks for your help.
Randy.
AA501 DC offset

 

The input capacitor of the AA501 is rated at 50V. I have a need to measure a 4VRMS AC signal with a +33.5V DC offset (i.e. before the coupling capacitor of an AC coupled audio amplifier). I have no wish to blow up my AA501 again ;-) so I am wondering if anybody has done this already without harm.

TIA

EJP
Re: Tektronix SC501 Calibration Instructions

 

I found a PDF of it here , without all the deliberate obfuscation practiced by the site below. PDF is available at several other sites.

EJP
Horizontal jitter on 11801

 

My 11801 has developed a horizontal jitter. Does anyone have any info about what I'm likely to need to replace? Or any source of component level information about the horizontal section?

I've got the 11801 service manual, such as it is, but it's not a lot of help for diagnosis. So unless someone has been there I'm probably best off just going through recapping the video section.

thanks,
Reg
7104 odd beam fault - whole screen illuminated

 

Tek fans,

I've just switched on for the first time a 7104 that I picked up in a
disposal auction recently. It came with the correct plugins (7A29, 7A29
with variable delay, 7B15 and 7B10) and the mainframe has its calibration
stickers intact so it probably hasn't been fiddled with.

It almost works, but not quite. I removed everything but the 7B10 timebase.
There is light on the screen, but it's not a spot. Rather, the whole screen
lights up while the timebase is sweeping. There is no movement of the beam
apparent, and there's no readout. The screen has some burn evident in the
readout areas and a horizontal burn line in the lower third, which seems to
be fairly typical.

The intensity controls work but the focus and beam finder seem to have no
effect. I didn't have a screwdriver handy to try adjusting the astigmatism.

Any clues before I start digging deeper? All ideas are welcome.

Thanks
Chtis
Re: Tektronix SC501 Calibration Instructions

 

Hi Colin,

Great suggestion - I forgot his address was at the bottom of the page. Email Sent!

Thank you and Best regards,

Jason
Re: Tektronix SC501 Calibration Instructions

 

Why not contact Kurt, the Admin of TekWiki and offer him the extra info? I'm sure he'd be glad to have it. His email address is on TekWiki at the bottom of the first page.

Colin.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Jason A. via Groups.Io
Sent: 22 August 2019 19:27
To: [email protected]
Subject: [TekScopes] Tektronix SC501 Calibration Instructions

Hello All,

I noticed that the scan of the SC501 manual on TekWiki was almost complete but was lacking a little bit of information, particularly in the maintenance/calibration section (looks like some things got overlaid during the scan). I have not validated the instructions on this link below yet, but wanted to share in case they help someone else:



Based on the description, it appears they are somewhat generalized, but hopefully they can be combined with the scan from TekWiki to fill in the missing info.

Thanks and best regards,

Jason
Tektronix SC501 Calibration Instructions

 

Hello All,

I noticed that the scan of the SC501 manual on TekWiki was almost complete but was lacking a little bit of information, particularly in the maintenance/calibration section (looks like some things got overlaid during the scan). I have not validated the instructions on this link below yet, but wanted to share in case they help someone else:



Based on the description, it appears they are somewhat generalized, but hopefully they can be combined with the scan from TekWiki to fill in the missing info.

Thanks and best regards,

Jason
Re: Tek 576 Curve Tracer HV Transformer winding

 

I agree. I used the same topology (layer winding with retrace) on my 453. Although it's no good for volume production, it's low-tech and accessible to the novice. See topic and photo album titled "453 HV Transformer Rewind". I built my winding machine from odds and ends, and I got a usable, reliable build on the first try even though I made mistakes.

But I cringe when I think of doing it again. I would, but only for love, not [reasonable] money. I wish Chuck Harris luck and skill getting his progressive process tuned again.

Dave Wise
________________________________________
From: [email protected] <[email protected]> on behalf of Mlynch001 <mlynch002@...>
Sent: Thursday, August 22, 2019 10:19 AM
To: [email protected]
Subject: Re: [TekScopes] Tek 576 Curve Tracer HV Transformer winding

Ulf,

Rewinding such a transformer is not for the faint of heart, the nervous or the impatient person. I appreciate your ability to do this successfully.


--
Michael Lynch
Dardanelle, AR

Winding some 1000 turns of 0.1mm copper wire the High-Voltage stylewas time consuming. Starting left to right ,each layer was insulated using capton tape.The copper wire was then braught back to to the startposition, hiddenunder yet some small pice of tape and the the next winding was startedfrom left to right.
This was made fully manually, just counting each layer and keepingtrack of the total number of turns.
Cheers
Ulf KylenfallSM6GXV
Re: Tek 576 Curve Tracer HV Transformer winding

 

Ulf,

Rewinding such a transformer is not for the faint of heart, the nervous or the impatient person. I appreciate your ability to do this successfully.


--
Michael Lynch
Dardanelle, AR
Re: Tek 2465B Startup Woes

 

Great information Chuck! Most of us sometimes forget that our RMS meters do
this! Thank you!

On Sun, Aug 18, 2019 at 12:58 PM Chuck Harris <cfharris@...> wrote:

Looking at your precise ripple values gives me the feeling
that you simply measured them using the AC(RMS) function of
your DVM. If that is the case, the true P-P ripple is more
like 2.8 times the values you measured.

When a -8V DC signal with a lot of ripple is measured on a
DC DVM, you tend to get a reading that is an average of the
ripple.

I would say your first task should be to recap your supply,
all of your ripple values look too high. In some cases, way
too high.. remember 2.8x RMS -> VP-P, and tek's specs for
ripple are in VP-P.

As to the voltage jumping up to 16V when you removed the load,
that is normal, as the series regulator can leak enough current
to make the incredibly light load your DVM presents, all the
way up to the unregulated supply's value.

-Chuck Harris

Stan wrote:
Thanks for the reply, Chuck!

Here are the power supply voltages and ripples, as measured at J119:

-15 measures -15.001 V with 0.99 mV of ripple
+5 measures +4.991 V with 33.86 mV of ripple
-15 UNREG measures -18.293 V with 28.1 mV of ripple
+10 REF measures +10.009 V with 1.34 mV of ripple

-5 measures -2.899 V with 8.71 mV of ripple <<
+15 measures +15.010 V with 0.58 mV of ripple
+87 measures -+86.799 V with 1.08 mV of ripple
+42 measures +42.484 V with 1.10 mV of ripple

-8 measures -4.291 V with 30.4 mV of ripple <<
+5 measures +4.978 V with 0.96 mV of ripple

So clearly there is something wrong with the -5 and -8 supplies. I
measured the unregulated output of the -8 supply at J232A Pin 5
(interconnect between the A3 and A2A1 boards), and it was -8.3. When I
removed the interconnect, the voltage jumped up to -16.5.

Is it reasonable to assume that the problem may well be with the filter
capacitors on the A2A1 board? I suspect that a shorted or leaky C1350 may
be pulling down the -8 line, and thereby pulling down the -5 line through
CR1334.

The next step is to remove the LVPS. I plan to do that later today.

Thanks,
Stan
Re: Tek 576 Curve Tracer HV Transformer winding

 

I got a .PDF of the winding specification and uploaded it to KO4BB manual sitebut I think that it may have ended up not in the \576-folder but in the rootsomewhere.
I rewinded mine successfully after having a friend print out a new bobbinon his 3D printer. I also had to design a winding machine for the purpose.
The dangerous part of rewinding was splitting the core which has to bedone using an oven or putting the core on a chemical boiler plateand heating it up.

Then, using thermal protection gloves, pulling the two halfes apartwas easy.

Winding some 1000 turns of 0.1mm copper wire the High-Voltage stylewas time consuming. Starting left to right ,each layer was insulated using capton tape.The copper wire was then braught back to to the startposition, hiddenunder yet some small pice of tape and the the next winding was startedfrom left to right.
This was made fully manually, just counting each layer and keepingtrack of the total number of turns.
Cheers
Ulf KylenfallSM6GXV
Re: Tek 2465B Startup Woes

Chuck Harris
 

Hi Stan,

In an effort to keep my stock of electrolytic capacitors reasonable,
I substitute the following in the 2465 power supply:

ORIGINAL ---> MY SUBSTITUTION
-------------------------------------------------------
180uf, 40V, and 250uf, 20V -> 330uf 50V United chemicon
100uf, 25V, -> 100uf, 25 or 35V, Nichicon
10uf, 100v, 10uf, 160V -> 10uf 160V Nichicon
3.3uf, 350V -> 3.3uf, 350V Nichicon
47uf, 25V, 47uf, 35V -> 47uf, 35V Nichicon
4.7uf, 35V -> 4.7uf 35V Nichicon
290uf, 200V (axial) -> 330uf, 200V (radial)
1uf NPE, 35V -> 1uf ceramic, 50V

And, don't forget the one or two caps in the HV supply.
(if they are bad, EHT ripple gets all over -15V)

100uf, 25V/35V -> 100uf, 35V Nichicon.



Stan wrote:

All seems to be well now. I found a high ESR 100uF cap on the A3 board in the -8v circuit (C1102). I ordered a bunch of 100uF/25V 105C caps and replaced all of them on both the A3 and the A2A1 boards. I also replaced the four radial electrolytics on the A5 board.

Now the scope powers up without errors and seems to be working properly.

I plan to replace all of the potential problem caps in the scope, but in some cases I'm having trouble finding the exact value replacements. For example, would there be a problem replacing the 250uF/20V caps with 330uF/25V caps? I know the tolerance given in parts list suggests that this would be acceptable, but I wanted to ask the opinion of those who have more experience with this than I. (Thanks, Chuck!)

Stan
Re: Tek 576 Curve Tracer HV Transformer winding

 

Tektronix 567 EHT rewinding pictures from Craig






Tektronix 567 EHT rewinding pictures from Craig


-----Mensaje original-----
De: [email protected] [mailto:[email protected]] En nombre de Bob Koller via Groups.Io
Enviado el: jueves, 22 de agosto de 2019 16:07
Para: [email protected]
Asunto: Re: [TekScopes] Tek 576 Curve Tracer HV Transformer winding

Peter,

Yes, the Tek drawing is on the KO4bb.com site under in the Tek 576 section.
I don't know know if anyone has rewound these, but a few years ago someone had a few new transformers made, albeit with a different mechanical construction. I tested one for him and it worked fine. Mounting was tight, but usable.
Unfortunately I don't recall his name..
Re: Tek 576 Curve Tracer HV Transformer winding

peter bunge
 

OK I found many references to making new ones long ago. It does not sound
practical.
Does anyone have a black one for sale?

On Thu, Aug 22, 2019 at 9:46 AM peter bunge via Groups.Io <bunge.pjp=
[email protected]> wrote:

Has anyone re-wound the HV transformer in the Tek 576 Curve Tracer?
Is there a link to show the number of turns on the windings?
Re: Tek 576 Curve Tracer HV Transformer winding

 

I knew someone here could remember where that drawing was.

Thanks Bob!

--
Michael Lynch
Dardanelle, AR
Re: Tek 576 Curve Tracer HV Transformer winding

Bob Koller
 

Peter,

Yes, the Tek drawing is on the KO4bb.com site under in the Tek 576 section.
I don't know know if anyone has rewound these, but a few years ago someone had a few new transformers made, albeit with a different mechanical construction. I tested one for him and it worked fine. Mounting was tight, but usable.
Unfortunately I don't recall his name..
Re: Tek 2465B Startup Woes

Bob Koller
 

Stan,
270uF caps work fine, I have installed literally hundreds of them in these scopes. Are you going to replace all the electrolytic caps, including the small non-polar parts? They have past it as well. Don't forget the Rifa firecrackers in the mains input.
Re: Tek 2465B Startup Woes

 

All seems to be well now. I found a high ESR 100uF cap on the A3 board in the -8v circuit (C1102). I ordered a bunch of 100uF/25V 105C caps and replaced all of them on both the A3 and the A2A1 boards. I also replaced the four radial electrolytics on the A5 board.

Now the scope powers up without errors and seems to be working properly.

I plan to replace all of the potential problem caps in the scope, but in some cases I'm having trouble finding the exact value replacements. For example, would there be a problem replacing the 250uF/20V caps with 330uF/25V caps? I know the tolerance given in parts list suggests that this would be acceptable, but I wanted to ask the opinion of those who have more experience with this than I. (Thanks, Chuck!)

Stan
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