Date   

7J20

 

Hi Kurt,
If you do decide to sell it please keep me in mind. I have one 7J20 with the J20. My 7J20 plugin acts up on a regular basis so I would love to have a spare since these are so rare.

I discovered atomic physics in college when I took a course on it and as a result I became fascinated by spectra. I used to go in the physics lab after hours to study the spectra of the various gas filled spectral tubes in a dark room using an optical spectrometer. I loved the purity of each spectral line and I tried to figure out a way to calculate their brightness.

When I discovered the 7J20/J20 could do this I was hooked. It took me years before I found one and it was missing the interconnecting cable so I was able to get it at a reduced price. After about 2 years of studying the schematics I managed to make myself a cable for it.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Kurt Swanson
Sent: Saturday, July 11, 2020 8:27 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Looking for

I have a 7J20. Unfortunately, I don't have the sampling head. I've had it for a long time, and when I got it, I knew it was uncommon, but I figured a sampling head would eventually turn up. No such luck - at least so far.
I got it wanting to do some optical spectroscopy work, and still would like to get it working for that purpose.

If anyone has a sampling head, let me know, otherwise I might reluctantly let this one go for sale or trade (and I do mean reluctantly).

Regards - Kurt





--
Dennis Tillman W7pF
TekScopes Moderator


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

unclebanjoman
 

Hi Albert,

thank you for your efforts.
I've just created a new photo album:

https://groups.io/g/TekScopes/album?id=250556

where you can see the component location mismatched with the schematic.
I think I can get the pattern by hand, at that point...

Max


Added album Tek S-6 latest version #photo-notice

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

unclebanjoman added the album Tek S-6 latest version: Views of the A4 preamp board component and solder side. The components do not coincide with the schematic


Re: Message from Dave Carpenter

DaveC <davec2468@...>
 

Thanks Dave for the quote from the manual.

What does the “CYCLE ERROR CLEAR routine (Exerciser 03)” involve?

Thanks, Dave C.

2465DVS for sale

-=-=-=-

On 12 Jul 2020, at 17:45, DaveH52 wrote:

According to my service manual page 6-12: "0D,ABCC> is the cycle mode failure indicator. When the CYCLE mode is activated (see CYCLE ERROR CLEAR Description), data will be written to the EAPROM about the first test failure that occurs. This information will be displayed until the operator performs the CYCLE ERROR CLEAR routine (Exerciser 03).


Re: Another 7D20 attenuator question

Dallas Smith
 

Hello again,

Thanks too all for your suggestions. Finally got it to work, no errors, after polishing the substrate pads. Got no answer for my question if the substrate pads are supposed to be gold plated? I think the relay problem has always been the substrate. What goes wrong with the relays? They have anti corrosion gold contacts after all, coil?

Changed the CCD & Ram board for the remaining problems.. Now for the full calibration. Any cautions when I re-calibrate this unit? I have no experience on this unit.

Dallas


Re: Tektronix 2230

Saroj Pradhan
 

Hi Harvey
Thank for reminding.
I will check.
Thanks
Saroj

On Thu, Jul 16, 2020, 8:39 PM Harvey White <madyn@...> wrote:

Please be careful to determine whether or not the transformer is an
autotransformer or is really an isolation transformer. Some voltage
converters are autotransformers, one tapped winding and a common
ground. They may not tell you.

Harvey


On 7/16/2020 10:40 AM, Saroj Pradhan wrote:
Hi Satbeginner
I have one transformer 220v/110v.
And 2230 also accepts 110v.
Transformer can supply up to 300w.
I think I can proceed with that one.
Thanks
Saroj


On Thu, Jul 16, 2020, 5:22 PM satbeginner <@satbeginner>
wrote:

No!

Be careful here!

Your scope under test must be:

Disconnected from ground, AND

be connected to a fully insulated line voltage, hence the isolation
transformer.

You will connect your working scope to the various testpoints as
indicated
by the service manual, and the primary switcher is connected to the line
voltage.

That's why you must isolate the scope under test when testing the
primary
switcher.

Take care,

Leo







Re: Tektronix 2230

Harvey White
 

Please be careful to determine whether or not the transformer is an autotransformer or is really an isolation transformer.  Some voltage converters are autotransformers, one tapped winding and a common ground.  They may not tell you.

Harvey

On 7/16/2020 10:40 AM, Saroj Pradhan wrote:
Hi Satbeginner
I have one transformer 220v/110v.
And 2230 also accepts 110v.
Transformer can supply up to 300w.
I think I can proceed with that one.
Thanks
Saroj


On Thu, Jul 16, 2020, 5:22 PM satbeginner <@satbeginner> wrote:

No!

Be careful here!

Your scope under test must be:

Disconnected from ground, AND

be connected to a fully insulated line voltage, hence the isolation
transformer.

You will connect your working scope to the various testpoints as indicated
by the service manual, and the primary switcher is connected to the line
voltage.

That's why you must isolate the scope under test when testing the primary
switcher.

Take care,

Leo




Re: 7A12 push button, relay switched, dual vert plug-in ?

Bill Perkins
 

The 7A12s I'm considering go for about $US35.00 and I have several known good 7A26s so I'm good. Thx>

Regards,
Roger


Re: Tektronix 2230

satbeginner
 

Hi Saroj,

300W should be enough, but please make sure it is an insulating transformer, and not a autotransformer.

Good luck,

Leo


Re: Tektronix 2230

Saroj Pradhan
 

Hi Satbeginner
I have one transformer 220v/110v.
And 2230 also accepts 110v.
Transformer can supply up to 300w.
I think I can proceed with that one.
Thanks
Saroj

On Thu, Jul 16, 2020, 5:22 PM satbeginner <@satbeginner> wrote:

No!

Be careful here!

Your scope under test must be:

Disconnected from ground, AND

be connected to a fully insulated line voltage, hence the isolation
transformer.

You will connect your working scope to the various testpoints as indicated
by the service manual, and the primary switcher is connected to the line
voltage.

That's why you must isolate the scope under test when testing the primary
switcher.

Take care,

Leo




Re: Tektronix 2246 flickering screen, ch2 not working.

grusus@...
 

After swapping tlc271 all channels are working fine. So this issue can be called fixed.


Re: P6042 Hall sensor

snapdiode
 

"I even bought a new (old stock) hall sensor (kit) from Sphere but it turned out to be completely useless
(much worse than the original)"

Did it come with the resistors?


Re: Tektronix 2230

satbeginner
 

No!

Be careful here!

Your scope under test must be:

Disconnected from ground, AND

be connected to a fully insulated line voltage, hence the isolation transformer.

You will connect your working scope to the various testpoints as indicated by the service manual, and the primary switcher is connected to the line voltage.

That's why you must isolate the scope under test when testing the primary switcher.

Take care,

Leo


Re: Tektronix 2230

Saroj Pradhan
 

Hi Satbeginner

Understood. If my under test oscilloscope is isolated from AC ground is it
safe to probe without isolation transformer?
Both oscilloscopes have two pin ac plugs.
Thanks
Saroj

On Thu, Jul 16, 2020, 2:18 PM satbeginner <@satbeginner> wrote:

Hi Saroj,

You must float the defective scope by means of a 1:1 isolation
transformer, and not the scope you use to measure the signals.

In my copy of the 2215A service manual this is mentioned in the page titled

POWER SUPPLY WAVEFORMS

Leo





Re: 7A12 push button, relay switched, dual vert plug-in ?

Roger Evans
 

Just looking at the pictures of the attenuator board in the manual, the relays appear to be from the same series that have been problematic in other 7k plugins. I don't know if some contact arrangements or coil voltages are more prone to failure than others. If the 7A12 offered for sale is 100% working and you have another vertical plugin that works reliably to trouble shoot any problems then only you can decide if you want to take the chance of future reliability issues. If it were me, I would be heavily biassed by the asking price!

Regards,

Roger


Re: Tektronix 2230

satbeginner
 

Hi Saroj,

You must float the defective scope by means of a 1:1 isolation transformer, and not the scope you use to measure the signals.

In my copy of the 2215A service manual this is mentioned in the page titled

POWER SUPPLY WAVEFORMS

Leo


Re: Tektronix 2230

Saroj Pradhan
 

Hello Satbeginner
Thanks
I will try to measure.
Both the oscilloscopes have to be connected through isolation transformer
or just either one is enough? Right now the 2230 chassis is isolated from
AC ground.
I had replaced C906 by 100uF 450v new capacitor.
Thanks saroj

On Thu, Jul 16, 2020, 1:23 PM satbeginner <@satbeginner> wrote:

Hello Saroj,

Imho the current of 1.4 - 1.44 Amp and the fact it runs like that for an
hour seems like good news to me.

Yes, the current is (somewhat) lower than Håkan mentioned in his document,
but also your voltage is a bit lower.

We have to start somewhere, so let's assume the transformer is ok.

I would like to do two things:

1. Check all components from the line input to the first switcher.

Also the bridge rectifier diodes CR901-904 and the DC voltage across C906.

If, for whatever reason, there is some serial resistance or a too low DC
input voltage, that could cause the first switcher going all the way in an
effort to still come up with the desired 43VDC.

2. Measure the gate voltage on the FET at power on.
If the FET is not properly switching on and off, the dissipation in the
FET would be too high, so it could die because of that.

But: you need a scope AND an isolation transformer to do that!

Will think more,

Leo




Re: Tektronix 2230

satbeginner
 

Hello Saroj,

Imho the current of 1.4 - 1.44 Amp and the fact it runs like that for an hour seems like good news to me.

Yes, the current is (somewhat) lower than Håkan mentioned in his document, but also your voltage is a bit lower.

We have to start somewhere, so let's assume the transformer is ok.

I would like to do two things:

1. Check all components from the line input to the first switcher.

Also the bridge rectifier diodes CR901-904 and the DC voltage across C906.

If, for whatever reason, there is some serial resistance or a too low DC input voltage, that could cause the first switcher going all the way in an effort to still come up with the desired 43VDC.

2. Measure the gate voltage on the FET at power on.
If the FET is not properly switching on and off, the dissipation in the FET would be too high, so it could die because of that.

But: you need a scope AND an isolation transformer to do that!

Will think more,

Leo


Re: P6042 Hall sensor

George Livanes
 

Hi,
Worked on several P6042's with Hall sensor problems.
I suggest you should not wast your time (or money) trying to repair.
I even bought a new (old stock) hall sensor (kit) from Sphere but it turned out to be completely useless
(much worse than the original)
I think the sensors just deteriorate with time if you use them or not.
Unfortunately it is very expensive technology to make such sensitive (and wide bandwidth) probes.
Regards
George


Re: Tektronix 2230

Saroj Pradhan
 

Hi Satbeginner
Did you go through my measurement.
Sorry to disturb you.
Thanks saroj



On Wed, Jul 15, 2020, 8:39 AM Saroj Pradhan via groups.io <sarojman.Pradhan=
gmail.com@groups.io> wrote:

Hello Satbeginner
Today I measured the current at inverter input, it draws 1.446A(with my own
built power supply)
I left the measuring setup as it is for 1 hour and there is no significant
change in current the last reading was 1.403A.
At this current level the beam gets shorter and the voltage drops to 35.6v.
Actually this happens frequently. When I get beam across the screen the
current is 1.44A and when the beam is shorter the current is 1.40A. That
should be the cause of external power supply.
I measured the current by fluke175 multimeter.
Thanks
Saroj


On Tue, Jul 14, 2020, 11:17 PM Saroj Pradhan via groups.io
<sarojman.Pradhan=gmail.com@groups.io> wrote:

Hello Satbeginner
Actually I forgot to mention that even u930 got faulty, r908open and
cr907
shorted.
To measure the current at that point with external power supply I have
the
same Powe supply that I built, which gives around 38v. Shall I proceed
with
this power supply to measure the current?
Now I have replaced all the component but for cr907 I do not have MUR460
so
replaced it by the one I had before MUR460.
I did power on the scope and I saw the trace. Input voltage to the
inverter is 41v this time. And I put the scope off.

One thing more, During first power on after correct (dot point) rewinding
of T906 I had r934, in the crowbar circuit, was disconnected. For Q935 I
have use tyn812. Now r934 is connected.
Thanks
Saroj



On Tue, Jul 14, 2020, 9:30 PM satbeginner <@satbeginner>
wrote:

Hello Saroj,

how disturbing it must be for you to repair this one.... :-(

One thing I can think of is the following:

Would it be possible to run the scope again from your external 43VDC,
while measure the current at that point?
The document Hakan wrote says the expected current into the secondary
power supply should be around 1,5 - 2 Amp.

If in your case the current is (much) higher, you might start looking
in
the secondary part first, before trying the primary power supply again
:-(

I will try to think of other approaches towards a real solution.

Hang in there,

Leo