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Re: 7603

Bill Perkins
 

I lately read that the 7603 was sold in -vast- numbers, maybe that's a clue.
I'm replacing a venerable R5113 dual beam, split screen storage mainframe I bought new in the late '70s with one and picking up a 7934 to drive around on a scope cart.
For me, that means 7K plug-ins throughout the lab and the 5K box on an assembly bench.

Bill

I was wondering about this the other day... many times I see people write something like: “My venerable and trusted 7603”, or some along those lines. And I‘ve come across this kind of comments quite numerous times. Why is that? Why does it seems to be more popular than a 7623? Is it because of the bigger screen? Is it because back in the day it was perhaps cheaper, and therefore more people opted for it instead of the one with “storage”? I’ve never had a 7603, but I do have a 7623 (not A), that I really like, and that is always on my bench despite the smaller screen.


7603

Stephen
 

I was wondering about this the other day... many times I see people write something like: “My venerable and trusted 7603”, or some along those lines. And I‘ve come across this kind of comments quite numerous times. Why is that? Why does it seems to be more popular than a 7623? Is it because of the bigger screen? Is it because back in the day it was perhaps cheaper, and therefore more people opted for it instead of the one with “storage”? I’ve never had a 7603, but I do have a 7623 (not A), that I really like, and that is always on my bench despite the smaller screen.


Re: Need 067-1051-00 right angle extender for 7D20

Dallas Smith
 

Thanks Egge for the heads up,

Didn't fine any on Ebay.
Maybe Le-Fong Lin could work one up if he is listening. :-)
Not sure if its possible to service without one.
Maybe solder a test point wire accessible after plugged in.

Dallas


Re: Tektronix 2230

Dave Hills
 

Varnishing accomplishes two things. It keeps moisture out and
prevents the wire in the windings from moving. If not secured
the wires will move in response to the current through them.
Maybe not problem in this small transformer, but a big one in
high current types and electric motors. Imagine the wires vibrating
against each other at the switching frequency, eventually wearing
away the insulation and creating a shorted turn.
It can't hurt and is usually done in a vacuum to assure completey
saturating the windings snd remove any moisture, followed by
a high temperature bake to harden the varnish deep inside the
windings.

Dave


Re: Need 067-1051-00 right angle extender for 7D20

Egge Siert
 

Hi Dallas,

The same RA Extender is used in the 067-1112-00 Service Kit for the 7A42.

Greetings,

Egge Siert


Need 067-1051-00 right angle extender for 7D20

Dallas Smith
 

Hi all,
Still working on my 7D20, successfully repaired the attenuator problem but now have self test errors 65432 & 654321.
Anyone design one of these, have the PCB Gerber files or a link to someones PCB project?
These seem to be unattainable on Ebay.

Dallas


Tek. 7904A and 7854 trace too bright (Z board working right and dc restoration diodes replaced)

Mark Vincent
 

I have the same problem in both scopes. The trace was normal one time and
too bright the next time it was turned on. The bias on the crt is 0V. I
have changed the diodes in the dc restoration circuits and doubler in the
crt cathode supply with MUR1100G, the 22meg carbons replaced with 1/2W 1%
types as the carbons checked about 30meg. I have replaced C82, C84, C86,
C87, C89, C91, C66, 69 and C72. The voltages were increased from 2kv to 3kv
and 4kv to 6kv types. I changed the 13meg resistor, R112, because it
checked about 20meg. That is now a 10meg and 3meg 1% type in series. I have
tried a new 741 opamp. Q129 tests fine on both units. Pulling the PDA,
plugs from the Z axis and larger one to the crt base make no difference in
the bias voltage, 0V between the cathode and G1. Keeping only the PDA
disconnected with the other two connected the trace is reduced. The crt
bias is set at max., 130V (should be cutoff) and int. on A and B at
minimum. There is no change in intensity with either reduced to a normal
bias and intensity. Turning up the intensity only makes the trace out of
focus. The vertical and horizontal is working fine. A trace can be seen if
an input is to the vertical plugin. The crt cathode voltage is correct. The
100V at the collector of Q129 is there and will vary with the high voltage
adjust. The 130V supply is correct. The two electrolytics are new Nichicon
ULD 5.6mfd 200V. I do not suspect a bad transformer since voltages are
there.

I am taking voltages from the 7904A here. The 7854 is likely the same in
voltages since the problem is exactly the same. The intensity is minimum
and bias at max. (130V). The 741 pin 2 -.02V, pin 3 .475V and pin 6 -1.63V.
The -2965 is there and the cathode and g! of the crt. The ac voltage at the
load side of R62 is 7.9v p-p. The ac voltage at the load side of R32 is
15.6V p-p. These two voltages seem too low. These voltages are in the
condition it is now with the PDA unplugged and other connectors connected.
If the PDA is connected, the trace is very bright and will fill the screen
as it should in normal operation. The power supply does not pulse when the
PDA is connected. It will if the brightness is too high in normal
operation. I have seen this when a restoration diode goes bad.The focus is
out when the PDA is connected. Likely the high brightness causing this. The
thick film resistor networks check fine. The proper operation voltages are
unknown (to me) and not on the schematic.The voltages from the Z board are
right. I adjusted them as said in the manual. Adjusting the focus does make
a difference in voltage and on the screen. The readout is working fine on
both units. That will adjust from off to full.

The 7854 was being used to test voltages between the two when it suddenly
developed the same problem(s) as the 7904A. It was on, working fine then
the problem happened. Voltages are now almost exactly the same as in the
7904A. Dust/dirt is not a problem as both are totally clean. Dust covers
are kept on them when not in use. The only difference between the boards is
the transistor is on the 7854 that goes back the power supply for beam
current detection. The 7904A board (A20) has a jumper between B and C where
the transistor could be and no other parts. This board was for both with
only some parts there or not depending upon which it was going in. Both
scopes and plugins have been overhauled, power supply voltages adjusted to
spec.. I know I have given a lot of details. I wanted to eliminate things I
know or suspected could be bad and to help anyone that knows what the
problem(s) is/are. Does anyone know what the problem(s) is/are? Thanks

Mark


S-6 troubleshooting (S/N B044657): updated schematics required

unclebanjoman
 

Hi all,
I started troubleshooting my S-6 head, using a 7S11/7T11 pair with extender for the S-6.
Symptoms are: large negative offset, exaggerated amplitude and waveform horribly distorted at any frequency.
Rotating the trims have negligible effect (just to exclude some wiper's contact problem).
I start to check the biasing circuit (U20A/B) and the series resistors between +50 and -50V but I discovered that the schematic and the pcb layout does not coincide with the documentation I have.
The A-4 preamp board is marked 670-1402-01; the strobe board is marked 670-1403-03. The S/N marked on the housing is B044657.
Anyone have an updated scheme?

Moreover, I noticed that on the schematic there are are two distinct grounds. But i don't know how the JFET may work if the gate is referenced to one ground (the one with the triangular shape) and its drain is connected to U20D that use the ground coming from the power supply interface..
Any ideas? I'm a little puzzled.

Thanks,

Max


Re: Tektronix 2230

Saroj Pradhan
 

OK let me see if I can find some at my home.
By the way do I need to dip the transformer in varnish and cure it.
Thanks Saroj

On Sun, Jul 12, 2020, 9:25 PM Dave Wise <david_wise@...> wrote:

For what it's worth, when I rewound my 453's high voltage transformer, I
insulated the layers with Scotch "Magic" tape, which is polypropylene. You
probably have some lying around, and it has worked great for years here.

Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Dave Hills
via groups.io <dadhills=mindspring.com@groups.io>
Sent: Saturday, July 11, 2020 4:57 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 2230

Kapton is a high temperature film not really needed in a transformer.
Polyester or mylar film tape is quite adequate for this application. You
will
often recognize it as yellow or white layer around modern transformer
windings.
It is also able to stretch, which is useful for keeping windings in place.
It has good
electrical characteristics, after all, it is used as the dielectric in
many capacitors.
Of course you would want a non-metalized type.

Dave









Re: Tek 465 Turns on, No Dot, No Trace

Stephen
 

On Sun, Jul 12, 2020 at 05:44 AM, Tom Miller wrote:


The HV module in the 465.

Tom
I see...

Thanks


Re: Tek 465 Turns on, No Dot, No Trace

 

The HV module in the 465.

Tom

On 7/12/2020 4:38 AM, Stephen wrote:
On Sat, Jul 11, 2020 at 03:44 PM, Tom Miller wrote:

I have done it both ways, by removing the crt plus all the other covers
and so on. It is just a long job. Take lots of pictures to aid reassembly.
Are you referring to the bridge rec in the 475A, or the HV multiplier in the 465?

Regards,

--
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Re: Tek 465 Turns on, No Dot, No Trace

Stephen
 

On Sun, Jul 12, 2020 at 04:40 AM, Laura wrote:


I heard some weird cracklings noises coming from the HV area, and a funny
smell. Nothing caught fire though. I turn everything down and .,.,.,.

If you hear crackling noises from the HV multiplier, check
for a carbon track down the side. This can be repaired by gouging
out the carbon and cleaning all outside surfaces with IPA.

Dust buildup in the HV area could also be the problem. Clean everything with a
Q-tip and
IPA.

I don’t know exactly where that came from. The area is very clean. But it definitely came from that area. Cleaning it with Q-tips and IPA was one of the first things I did so I could actually see if anything had burned or exploded.

The crackling sounds and the weird smell (not a burning smell), appeared for the the first time when I depressed the Beam Finder. Almost the same happened when I cranked the Intensity.
I didn’t exactly see a “trace”, but rather a blurry and unfocused glow. But at least, it was finally somehow alive.

Regards


Re: Tektronix 2230

Dave Wise
 

For what it's worth, when I rewound my 453's high voltage transformer, I insulated the layers with Scotch "Magic" tape, which is polypropylene. You probably have some lying around, and it has worked great for years here.

Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Dave Hills via groups.io <dadhills=mindspring.com@groups.io>
Sent: Saturday, July 11, 2020 4:57 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 2230

Kapton is a high temperature film not really needed in a transformer.
Polyester or mylar film tape is quite adequate for this application. You will
often recognize it as yellow or white layer around modern transformer windings.
It is also able to stretch, which is useful for keeping windings in place. It has good
electrical characteristics, after all, it is used as the dielectric in many capacitors.
Of course you would want a non-metalized type.

Dave


Re: Tek 465 Turns on, No Dot, No Trace

Laura
 

I heard some weird cracklings noises coming from the HV area, and a funny smell. Nothing caught fire though. I turn everything down and .,.,.,.
If you hear crackling noises from the HV multiplier, check
for a carbon track down the side. This can be repaired by gouging
out the carbon and cleaning all outside surfaces with IPA.

Dust buildup in the HV area could also be the problem. Clean everything with a Q-tip and
IPA.


Re: R7704+7A18+7B53A in Newport Beach, CA to part with

ChrisBeee
 

Hello Dave,
just to be sure: did you get my PM?
Chris


Re: Restoring 545b

Chuck Harris
 

It would help, only a little, to know which diode,

There are about 6 1N3194's (0.75A, 400PIV), which
can be replaced with a 1N4007 (1A, 1000PIV).

-Chuck Harris



Jayadamski728@... wrote:

Hi all

One of the bridge rectifier diodes in the power supply has shorted ... I was wondering what a suitable replacement would be ?




Re: Restoring 545b

Stephen
 

On Sat, Jul 11, 2020 at 11:28 PM, <Jayadamski728@...> wrote:


Hi all

One of the bridge rectifier diodes in the power supply has shorted ... I was
wondering what a suitable replacement would be ?
Look at the schematic which you could download from TekWiki, I guess.
It’ll probably tell you the characteristics of that rectifier. Replace it with a suitable modern replacement having the same voltages/power handling. That shouldn’t be too hard to find.


Re: Tektronix 2230

Saroj Pradhan
 

Hi jim;Dave and Satbeginner
Thanks for your good and valuable suggestion.
I decided to salvage some tapes from old transformer.
I think that should work.
Thanks
Saroj

On Sun, Jul 12, 2020, 5:42 AM Dave Hills <dadhills@...> wrote:

Kapton is a high temperature film not really needed in a transformer.
Polyester or mylar film tape is quite adequate for this application. You
will
often recognize it as yellow or white layer around modern transformer
windings.
It is also able to stretch, which is useful for keeping windings in place.
It has good
electrical characteristics, after all, it is used as the dielectric in
many capacitors.
Of course you would want a non-metalized type.

Dave




Re: Restoring 545b

Jayadamski728@...
 

Hi all

One of the bridge rectifier diodes in the power supply has shorted ... I was wondering what a suitable replacement would be ?


Added album 475A weird trace #photo-notice

TekScopes@groups.io Notification <TekScopes@...>
 

Stephen added album 475A weird trace: This is the trace I saw after replacing the mains fuse on my 475A. Turned it off immediately after I took the picture.