Date   

Re: 485 super weak brightness control

Carl Hallberg
 

When I wrote my reply, I didn't have the 485 book in front of me. If you look at foldout <10> you will see there are timing resistors for "A"  and timing resistors for "B". I don't think it is cap either.  Been many years since I looked at diagram.  Still think it is resistor, maybe not.  There is also interaction of 5,2,1  because of some paralleling values. Look at switch diagram at bottom of page.
Carl

On Thursday, April 22, 2021, 12:26:41 PM CDT, Ondrej Pavelka <info@vintageaudiorepairs.eu> wrote:





Hi, thanks for The suggestion but based on my understanding the B sweep
generator is used for both The A sweep as well as B sweep. So that cannot
be the cap. That would also impact B sweep



On Thu, 22 Apr 2021, 18:18 Carl Hallberg via groups.io, <n9ess=
yahoo.com@groups.io> wrote:

Check timing resistor, capacitor for faster B sweep. Might be the problem.
Mine was for slower sweeps.  See my email of Sept 21, 2017.
Carl W9CJH




On Thursday, April 22, 2021, 10:09:58 AM CDT, Ondrej Pavelka <
info@vintageaudiorepairs.eu> wrote:





Guys,

New Relays arrived and nearly all is healed. When B is selected all works
flawlessly, when A is selected everything works up till the 521 range. In
521 it's not displaying properly. More in the video

I'm so happy it's nearly there now!

https://youtu.be/xCO4kJbXaMw






On Fri, 26 Mar 2021, 01:21 Raymond Domp Frank, <hewpatek@gmail.com> wrote:

On Fri, Mar 26, 2021 at 12:48 AM, Ozan wrote:


I agree sometimes stepping back and looking with fresh eyes helps. Let
us know
when you want to bounce off ideas again.
Ozan
I fully concur, Ozan.

Raymond















Tek 050-2562-03 upgrade kit for 2430A

 

I found one of these, complete with 7 EPROMS 160-6491-01 to 160-6497-01, and a SONY Low power
SRAM, CXK58257AP-12L. these are some upgrade for the 2430A scope (marked right on them). I don't have
any details on the kit, there is no paperwork with it, so as-is.

These are all 1991 date codes, so EPROM contents can be iffy at that age, however, they can be read out and re-programmed to refresh the image, or used as is. If you can use them, they have to ship in a small box, so can't go for free, but $20 plus shipping would do it. I am not brave enough to try a padded bag.

There's also lots of free Tek stuff up on the stuff page, and general goodies at the bottom in the free section. never know, something might catch your eye. https://www.sphere.bc.ca/test/stuffday.html

does anybody have an RPR for the 050 kits or 160 parts? I did not see anything on the tekwiki site.

all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.


Re: 485 super weak brightness control

Tom Lee
 

Gratulujeme, Ondrej! You're almost all the way there.

-- Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 4/22/2021 08:09, Ondrej Pavelka wrote:
Guys,

New Relays arrived and nearly all is healed. When B is selected all works
flawlessly, when A is selected everything works up till the 521 range. In
521 it's not displaying properly. More in the video

I'm so happy it's nearly there now!

https://youtu.be/xCO4kJbXaMw






On Fri, 26 Mar 2021, 01:21 Raymond Domp Frank, <hewpatek@gmail.com> wrote:

On Fri, Mar 26, 2021 at 12:48 AM, Ozan wrote:

I agree sometimes stepping back and looking with fresh eyes helps. Let
us know
when you want to bounce off ideas again.
Ozan
I fully concur, Ozan.

Raymond







Re: Tek 7844 Alphanumeric Display Issues

 

Readout position should be controlled by a pot (r2700) on the Beam 2 vertical boards.

Sounds most likely you have a problem with the auxiliary input amplifier on the Beam 2 vertical board. Maybe that pot is OC?

See Pages 3-24 and on, 5-35 and on and schematic <10>

David.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Liam Perkins
Sent: 22 April 2021 19:00
To: tekscopes@groups.io
Subject: [TekScopes] Tek 7844 Alphanumeric Display Issues

I have a 7844, ser. no. B173417, that works fine but for the readout
display which is shifted upwards 5 divisions, puting the top half of
the display off the screen.

According to the 7K-series Readout System on the TekWiki here:

https://w140.com/tekwiki/wiki/7000_series_readout_system

there were three versions of the readout display hardware; a) the
initial all-analogue, ROM-based version, b)the late-80s 2732
EPROM-based version and, c) a third generation readout designed around
an 80C31 micro-controller.

Mine is the EPROM version and despite buying a hard copy manual off
eBay and downloading everything from the TekWiki I cannot find a
manual describing my unit so I don't know where to find the pots
that'll put the display where it belongs; assuming that's the problem.
I've fiddled the pots on the EPROM board and found only one that
effects the readout, by changing the character size.

Does anyone have any experience with this, or access to the correct
manual or the version number of same ?

TIA
Liam @ PEARL, Inc.


Re: Tek 7844 Alphanumeric Display Issues

Mark Vincent
 

Liam,

Look on the vertical board mounted to the center support facing the right side of the scope. It will be on the same side as the readout board. There is a ro cent. control in the center of the three pots at the top of the board. That is likely the cause for the readout problem.

Mark


Tek 7844 Alphanumeric Display Issues

Liam Perkins
 

I have a 7844, ser. no. B173417, that works fine but for the readout
display which is shifted upwards 5 divisions, puting the top half of
the display off the screen.

According to the 7K-series Readout System on the TekWiki here:

https://w140.com/tekwiki/wiki/7000_series_readout_system

there were three versions of the readout display hardware; a) the
initial all-analogue, ROM-based version, b)the late-80s 2732
EPROM-based version and, c) a third generation readout designed around
an 80C31 micro-controller.

Mine is the EPROM version and despite buying a hard copy manual off
eBay and downloading everything from the TekWiki I cannot find a
manual describing my unit so I don't know where to find the pots
that'll put the display where it belongs; assuming that's the problem.
I've fiddled the pots on the EPROM board and found only one that
effects the readout, by changing the character size.

Does anyone have any experience with this, or access to the correct
manual or the version number of same ?

TIA
Liam @ PEARL, Inc.


Re: 560 Series Plugin Dimensional Drawings

snapdiode <snapdiode@...>
 

I have never seen a full mechanical drawing with dimensions for any plugin, really. Would be nice, must exist somewhere.


Re: 485 super weak brightness control

Ondrej Pavelka
 

Hi, thanks for The suggestion but based on my understanding the B sweep
generator is used for both The A sweep as well as B sweep. So that cannot
be the cap. That would also impact B sweep



On Thu, 22 Apr 2021, 18:18 Carl Hallberg via groups.io, <n9ess=
yahoo.com@groups.io> wrote:

Check timing resistor, capacitor for faster B sweep. Might be the problem.
Mine was for slower sweeps. See my email of Sept 21, 2017.
Carl W9CJH




On Thursday, April 22, 2021, 10:09:58 AM CDT, Ondrej Pavelka <
info@vintageaudiorepairs.eu> wrote:





Guys,

New Relays arrived and nearly all is healed. When B is selected all works
flawlessly, when A is selected everything works up till the 521 range. In
521 it's not displaying properly. More in the video

I'm so happy it's nearly there now!

https://youtu.be/xCO4kJbXaMw






On Fri, 26 Mar 2021, 01:21 Raymond Domp Frank, <hewpatek@gmail.com> wrote:

On Fri, Mar 26, 2021 at 12:48 AM, Ozan wrote:


I agree sometimes stepping back and looking with fresh eyes helps. Let
us know
when you want to bounce off ideas again.
Ozan
I fully concur, Ozan.

Raymond















Re: 485 super weak brightness control

Carl Hallberg
 

Check timing resistor, capacitor for faster B sweep. Might be the problem. Mine was for slower sweeps.  See my email of Sept 21, 2017.
Carl W9CJH

On Thursday, April 22, 2021, 10:09:58 AM CDT, Ondrej Pavelka <info@vintageaudiorepairs.eu> wrote:





Guys,

New Relays arrived and nearly all is healed. When B is selected all works
flawlessly, when A is selected everything works up till the 521 range. In
521 it's not displaying properly. More in the video

I'm so happy it's nearly there now!

https://youtu.be/xCO4kJbXaMw






On Fri, 26 Mar 2021, 01:21 Raymond Domp Frank, <hewpatek@gmail.com> wrote:

On Fri, Mar 26, 2021 at 12:48 AM, Ozan wrote:


I agree sometimes stepping back and looking with fresh eyes helps. Let
us know
when you want to bounce off ideas again.
Ozan
I fully concur, Ozan.

Raymond






Re: 560 Series Plugin Dimensional Drawings

David Holland
 

Thanks, there were a few in there..... At least enough to confirm that my
seldom used (and cheap) calipers weren't completely whacked....

Additionally, I learned what the little plastic tab in back, on the bottom,
is really for. 560 power supply compatibility, and not just they stand up
on their backs better in one position than the other. :-)

Cheers,

David


On Wed, Apr 21, 2021 at 10:57 PM snapdiode via groups.io <snapdiode=
yahoo.com@groups.io> wrote:

There might be some dimensions here

https://w140.com/tekwiki/wiki/040-0245-00






Re: 485 super weak brightness control

Ondrej Pavelka
 

Guys,

New Relays arrived and nearly all is healed. When B is selected all works
flawlessly, when A is selected everything works up till the 521 range. In
521 it's not displaying properly. More in the video

I'm so happy it's nearly there now!

https://youtu.be/xCO4kJbXaMw

On Fri, 26 Mar 2021, 01:21 Raymond Domp Frank, <hewpatek@gmail.com> wrote:

On Fri, Mar 26, 2021 at 12:48 AM, Ozan wrote:


I agree sometimes stepping back and looking with fresh eyes helps. Let
us know
when you want to bounce off ideas again.
Ozan
I fully concur, Ozan.

Raymond






Re: Alert for 519 owners - The significance of the Gold GR Connectors

Egge Siert
 

Hi to All,

With SN 1020 and higher the Outer Connectors are Gold Plated. Just readed it in the Manual (Mechanical Parts List).

Greetings,

Egg Siert


Re: 560 Series Plugin Dimensional Drawings

snapdiode <snapdiode@...>
 

There might be some dimensions here

https://w140.com/tekwiki/wiki/040-0245-00


Re: Free new Tek 152-0383-00 SMTD-898 Tunnel Diode

snapdiode <snapdiode@...>
 

The diode is missing. I would like a real Tek part.


Re: PG506 Repair - I had a Great Day today/

tek_547
 

That is really a very detailed explanation Michael, very much thanx for that! In the weekend or next week I have the time to work on the PG506 because the coming days I´m busy with other things.
Working and measuring on the PG506 need all your attention (floating ground) so I must have time for it.
You gave me more than enough things to sort out that I can check, so when I know more I give a reply.

Furthermore thanks for your effort and next week hopefully I know more, René


Re: 468 Digital Storage scope

Michael W. Lynch
 

Dr. Zeller,

Do you have the Service manuals for this unit? If not, I would strongly advise you to cease working until you get the correct service manuals (at least get a digital copy). I have the paper manuals, which I prefer. I also have 3 of these scopes that I have repaired and the manual is essential to the process. These scopes are extremely complex and diagnosis or repair will be next to impossible without the manuals.

That being said, The analog section is almost identical to the 465B, so that helps. You can test for signals at or just prior to the deflection plates. The test points and wave forms are all shown in service manuals.

There is not any HV present on the deflection plates, as there is with the Cathode heater.

Good luck with your repairs.

--
Michael Lynch
Dardanelle, AR


Re: PG506 Repair - I had a Great Day today/

Michael W. Lynch
 

On Wed, Apr 21, 2021 at 03:51 AM, tek_547 wrote:

René,

Good day!

You have done a lot of work, way more that I have done. Thanks for the details, this eliminates some of the thing that could have effected your unit.

Balance of reply is INTERLEAVED below

When "I push the variable in" I see the "88" with the decimal point in the middle.
This is Good and Normal. Indicates that the LED are capable of function once the proper signals are restored.

I said before that only the HIGH led is continue working but that is not
correct. It is the LOW led that is all ways on so sorry about that.
ANSWER: Not a problem, that will likely be cured along with the display function.

But the 5V1 at the collector from Q70
is a bit low; about 4,75V The 5V from the power supply schematic 1 (lower left
corner) is 5,03V so this looks normal.
Is on yours PG506 the 5V also a bit low after Q70 ? Maybe this is important.
This Should not be a problem, I will check mine to confirm voltages at this point. I believe that they are using Q70 as a on/off switch for the display when in "Std. Amplitude Variable mode".

The parts that I changed is a long list so here we go:
U665, 666, 667 and 668 changed (no difference)
U670 and U671 changed (no difference)
U673 and U675 changed (no difference)
U615 changed (no difference)
U430 and U460 changed (no difference)
U470 changed (no difference)
U400 changed (no difference)
Furthermore are most of the transistors checked so that there are no shorts.
ANSWER: WOW! This is a HUGE list. Specifically on U400, have you checked for wave forms at the various pins of your "New" U400. If you have pins stuck High or Low (missing wave forms), then your problem is obviously before or after that IC. Check to see that you have wave forms at pins 1~6 and pins 8~13. Probe carefully to avoid shorting between pins. Pin #7 is Ground and Pin#14 is 5V Supply. All other pins will have some sort of pulse train if the instrument is working correctly (sans the display).

Did you confirm that the other remaining 156-0067-00 (741CN) op amps are all good? These would be U50, U200, U240,U330, U375 in addition to the two that you already changed. Most of these are in sockets, so they are not a major problem to change. I also added sockets for U200,U240,U255 and U480 at the time these were replaced. I cannot say for sure that U255 and U480 (opto-couplers) were bad, however I had the board out and the desoldering pump hot, so it was a simple task to remove them, add sockets and install new 4N27's.

Regarding transistors, I found two 151-0223-00 NPN (Q435 and Q535) that were bad on my unit and they were the final two pieces that restored the unit to operation. I have the luxury of a Type 576 Curve tracer for testing, but you can test these and see if they are bad or not by other methods. I replaced these with 2N3904 parts and they worked just fine. Confirm the 4V 1kHz square wave pulse signal at Pin #8 U400 then look for that same signal at R532, then on the base of Q535. Remove and check Q535. I suspect that you will find Q535 to be defective.

You made no mention of diodes, you would be wise to check all the diodes and confirm they are good. I found a couple of bad ones early on. Those were all 152-0141-02 (1N4152R) which had failed.

And also maybe interesting is the fact that T130 in the power supply is about
70°C when the STD AMP switch is activated. So not possible to you put your
finger on it.
When it is on FAST RISE or HIGH AMPL. the temperature is more normal (about
45°C).
Has your PG506 the same behaviour about the temp from T130?
ANSWER: I will need to check this out.and report back. I do not remember mine being hot.

So the few things I did not changed are;
The display board A4 (a bit clumsy to remove) and the two opto couplers U480
and U255 (do you have a substitute number for that type?)
ANSWER: 156-0399-00 Opto Couplers are 4N27. You can find these and many more useful cross references in the TEKTRONIX SEMICONDUCTOR Common Design Parts Catalog, Available at TEKWIKI
link: http://w140.com/Tektronix_Xref_sm.pdf

I think the problem is in the display section (board A4) or in the digital
voltmeter circuit (schematic 3) but maybe you have other suggestions.
ANSWER: I am thinking a bad diode or transistor.

I´m glad to hear what you think about and maybe I get it work normal after a
while, René
Anything that is not clear, please ask me to elaborate. Sometimes I am lacking in my explanations.

Sincerely,

--
Michael Lynch
Dardanelle, AR


Re: 492P signal amplitude error and error 58

Attilio
 

Thanks Bob,
I cannot locate the NEC mm765 RF amp or the uPC1764A in the 492P.
As soon as I get the spare, I try to replace the 1st LO YIG.

--Cheers
Attilio


560 Series Plugin Dimensional Drawings

David Holland
 

Hi,

Anyone happen to know if there are dimensional drawings for the 560 series
plugins floating about?

I'm thinking about taking a stab at modelling a 3D printed plugin
protector/container.

Yeah, obviously, I can pull out the ol' micrometer and measure one, but
being lazy, I thought I might ask if someone was aware of something and
save myself some effort.

Thanks & Cheers,

David


Re: 468 Digital Storage scope

Dr. Manfred K. Zeller
 

Can I measure the horizontal an the vertical signal direct on the tube
connection?
Direct on the two wires on each side.
The digital part is disconnected.
With a second Oszilloskop.
Or is a voltage in addition there - like on the heater filament?
Or there are other testpoints to see the horizontal and vertical signals?
Thanks a lot!

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