Date   
Re: 7904 - Very Dim Trace

Jim McIntyre
 

OK - reading p 3-65 (Control Grid DC restorer) from the 7904 manual...

Starting to make sense...

Re: 7904 - Very Dim Trace

Ed Breya
 

There are typically two ways to get DC-coupled Z-axis control on scope CRTs. One is to generate a high voltage, similar to that used for the cathode supply, and stack it onto the ground-referenced Z-axis signal. This is what's applied to the control grid. The other way is to use a DC-restorer circuit, which is basically an AC-coupled charge pump, with the AC swing proportional to the ground-referenced Z-axis signal. It's coupled capacitively and rectified, and stacked onto the cathode supply, then applied to the control grid.

Either way, the control grid is indeed usually negative with respect to the cathode, by maybe up to 100V or so, and it controls the beam current. There are pluses and minuses to each approach.

Ed

Re: OT: Win 8.1 and 10?

n4mf_sc
 

VS6 ? and VS11 are basically 2 different animals. Code written in 6 ? will have to be reworked for 11 or 13 or 15 or Community which I am running now. The coding models and commands have changed greatly over the years, as has so much more. I had to revamp code 2 times for a Fire Flow (water needed) calculations program I wrote that started in QuickBasic and I ported to VS 95 in VB. It's no longer being reworked but I do have some other items I have been playing around with...

Yes I know how my PC runs "under the hood"....

The installer is getting a out of range response from the OS query and going to the unknown OS error out.

Mitch
N4MF

VS Community is free. The EULA lays out what you can do with it which is a bit relaxed from Express. If It's gonna be commercial you will still need pro or better, The EULA is different.

Re: Tek TM500 setups

 

Hi David,
<snip> The DD501 phase lock loops the FG504.
Are you sure about that? The DD501 is a digital delay plugin. The FG504 is an analog signal generator with built in sweep capability already in it. AFAIK these two plugins don't have anything in common. Of course I would be happy to learn of yet another way to interconnect Tek plugins.

According to the DD501 manual it can be used for counted burst operation when used with a PG508 pulse generator. I didn't see any other mention of it being used with any other plugin in the DD501 manual.

The FG504 is an extremely versatile instrument. It is capable of generating many complex waveforms (within limits) when swept by external signal sources. You can feed a signal from a ramp generator, or any of the function generator plugins into the VCF input of the FG504. But the output variation of the FG504 is limited to two decades of range at a time by default unless you modify it. You can also feed a phase lock signal to the FG504's Trigger Input BNC connector. But I am not sure you can simultaneously feed a sweep signal in AND phase lock to it.

I suggest you give it a try with a simple setup using an FG501 / FG502 (or any other plugin that has both a function output and a trigger output) to drive the FG504 to see if you can get the FG504 to phase lock on the external sweep signal. Let us know what happens.

Dennis Tillman W7PF

-----Original Message-----
Sent: Tuesday, February 09, 2016 6:26 PM
Subject: [TekScopes] Tek TM500 setups

Hi Everyone, I was wondering if anyone has experimented with pairing a RG501 sweep generator with Any of the FG Function Generators particularly the FG504 40mhz function generator also the combination of RG 501 ,DD 501, FG501, would give you a swept 40mhz function generator that is phase locked?

The DD 501 phase lock loops the FG504.

Wonder if anyone has used such a setups, if so please elaborate.

Thanks kindly.
Dave N9OOQ

------------------------------------
Posted by: David J Nushardt <daven9ooq@...>
------------------------------------

Re: TDS4020A Power Supply Issues

Ed Breya
 

If the PS is anything like that in the TDS754A or TDS544A, search the past messages here going back up to about three or four months, and you can see what I went through in fixing the small standby supply. There are two versions in the older scopes - a transistor blocking oscillator/flyback type, and a newer one with an SMPS IC that looks like a TO-220 transistor. The 544A uses the transistor version, and the one in the 754A is the IC type - a TOP200, which was shot. The data sheet is available online.

Ed

Re: 7904 - Very Dim Trace

Jim McIntyre
 

It's P31. Sweep mag is off. (I may not be the brightest bulb in the string, but I'm not overlooking something like this...)

I'll have a HV probe tomorrow to check the cathode and PDA voltages and will report back. Let's just assume, for the moment that these are OK.



There's something fundamental here I'm missing...



Assume we have a static display (no blanking because all chop modes are off, and we're in XY mode)


The cathode is at -3 kV. Doesn't the control grid (Pin 3 of the CRT) need to be slightly more negative? ie -3.050 kV or something of that order? How does this happen?

Re: External TO-3 Cover for Tek equipment on Ebay right now

n4buq
 

Hi Dennis,

I suspected as much. I was just making sure it was indeed form over function in this case as the other way's cheaper! :)

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "'Dennis Tillman' @Dennis_Tillman_W7pF [TekScopes]" <TekScopes@...>
To: TekScopes@...
Sent: Tuesday, February 9, 2016 7:16:19 PM
Subject: RE: [TekScopes] External TO-3 Cover for Tek equipment on Ebay right now

Hi Barry,
Yes, this would work as well although it does not LOOK like the Tek part.
Some collectors prefer to replace missing parts with New Old Stock (NOS)
parts from Tek.
Dennis Tillman W7PF

-----Original Message-----
Sent: Tuesday, February 09, 2016 5:07 PM
Subject: Re: [TekScopes] External TO-3 Cover for Tek equipment on Ebay right
now

While it's not the TEK part, wouldn't one of these work?

http://www.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkey4634

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "'Dennis Tillman' @Dennis_Tillman_W7pF [TekScopes]"
Sent: Tuesday, February 9, 2016 6:57:28 PM
Subject: [TekScopes] External TO-3 Cover for Tek equipment on Ebay
right now

If I recall correctly, a few months ago somebody was looking for the
plastic / rubber cover for a TO-3 transistor that was mounted on the
outside of a rear panel of a piece of Tek equipment.

There is one of these on Ebay at the moment for a Buy It Now price of
$4.75.
There are 3 available at

http://www.ebay.com/itm/Tektronix-200-0692-00-Transistor-Cover-/361316
897529 ?hash=item54202a52f9:g:xjYAAOSwpdpVdyUo

I have no connection with the seller, etc.
Dennis Tillman W7PF
------------------------------------
Posted by: Barry <n4buq@...>
------------------------------------


Tek TM500 setups

David J Nushardt <daven9ooq@...>
 

Hi Everyone, I was wondering if anyone has experimented with pairing a RG501 sweep generator with Any of the FG Function Generators particularly the FG504 40mhz function generator also the combination of RG 501 ,DD 501, FG501, would give you a swept 40mhz function generator that is phase locked?

The DD 501 phase lock loops the FG504.

Wonder if anyone has used such a setups, if so please elaborate.

Thanks kindly.
Dave N9OOQ

TDS4020A Power Supply Issues

Biff Wheeler
 

I have a new to me TDS420A, built in 1995, very clean on the inside except for all the dust (couldn't find any sign of capacitor leaking or corrosion, with no power out. I've got power to the main power supply board, looks to be about 300-320v sine wave coming in and the rectifier seems to be doing it job since I have a 1/2 positive and 1/2 negative clipped signals going into the transformer. I have nothing coming out. I don't see a high frequency signal being generated like I have on other SMPS, I pulled one out of a printer to have for a reference, so I'm stumped. Is there a control circuit that is essentially shutting off the secondaries? Since I've taken the EMI filter and power supply out of the scope, do I need to give the PS a "turn on" signal?
I've read quite a bit about the TDS line and the capacitor issue so before I even turned the thing on I did an inspection and the boards look great so I'm hoping with a bit of troubleshooting I can get this thing up and running again.

Re: OT: Win 8.1 and 10?

Richard R. Pope
 

Mark and et al,
I want to thank everyone for their inputs and their discussions on
this subject. I have done a lot of reading and I have considered all
that has been said here. I knew that this was the right place to come. I
believe that it is time to stop this thread.
I am going to stay with 8.1 for right now. There is a lot to learn
here. I have also done some playing around with Linux going back more
that a decade. My other machine is triple boot with XP, Server 2003, and
Linux. Something that keeps holding me back on Linux is the learning curve.
There is something else that I would like to cover. I tried to
install VB6 on this machine and it won't work. Is Visual Studio 11
compatible with Visual Studio 6?
Again thanks for everything,
rich!

On 2/9/2016 7:01 AM, Mark wendt.mark@... [TekScopes] wrote:

Or better yet, upgrade to Linux. ;-)

Mark

On 02/08/2016 06:51 PM, Artek Manuals manuals@...
[TekScopes] wrote:
Rich
AMEN
Dave


On 2/8/2016 6:39 PM, 'Richard R. Pope' mechanic_2@...
[TekScopes] wrote:
Hank,
Download the full version of Win10 and then you can do a fresh
install. This would allow you to get rid of the hidden restore
partition
on the hard drive. This is another reason I don't buy pre-built
computers. I want the OS disk and not a restore partition.
Thanks,
rich!

Re: External TO-3 Cover for Tek equipment on Ebay right now

 

Hi Barry,
Yes, this would work as well although it does not LOOK like the Tek part. Some collectors prefer to replace missing parts with New Old Stock (NOS) parts from Tek.
Dennis Tillman W7PF

-----Original Message-----
Sent: Tuesday, February 09, 2016 5:07 PM
Subject: Re: [TekScopes] External TO-3 Cover for Tek equipment on Ebay right now

While it's not the TEK part, wouldn't one of these work?

http://www.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkey4634

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "'Dennis Tillman' @Dennis_Tillman_W7pF [TekScopes]"
Sent: Tuesday, February 9, 2016 6:57:28 PM
Subject: [TekScopes] External TO-3 Cover for Tek equipment on Ebay
right now

If I recall correctly, a few months ago somebody was looking for the
plastic / rubber cover for a TO-3 transistor that was mounted on the
outside of a rear panel of a piece of Tek equipment.

There is one of these on Ebay at the moment for a Buy It Now price of $4.75.
There are 3 available at

http://www.ebay.com/itm/Tektronix-200-0692-00-Transistor-Cover-/361316
897529 ?hash=item54202a52f9:g:xjYAAOSwpdpVdyUo

I have no connection with the seller, etc.
Dennis Tillman W7PF
------------------------------------
Posted by: Barry <n4buq@...>
------------------------------------

Re: External TO-3 Cover for Tek equipment on Ebay right now

n4buq
 

While it's not the TEK part, wouldn't one of these work?

http://www.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkey4634

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "'Dennis Tillman' @Dennis_Tillman_W7pF [TekScopes]" <TekScopes@...>
To: TekScopes@...
Sent: Tuesday, February 9, 2016 6:57:28 PM
Subject: [TekScopes] External TO-3 Cover for Tek equipment on Ebay right now

If I recall correctly, a few months ago somebody was looking for the plastic
/ rubber cover for a TO-3 transistor that was mounted on the outside of a
rear panel of a piece of Tek equipment.



There is one of these on Ebay at the moment for a Buy It Now price of $4.75.
There are 3 available at

http://www.ebay.com/itm/Tektronix-200-0692-00-Transistor-Cover-/361316897529
?hash=item54202a52f9:g:xjYAAOSwpdpVdyUo



I have no connection with the seller, etc.

Dennis Tillman W7PF







External TO-3 Cover for Tek equipment on Ebay right now

 

If I recall correctly, a few months ago somebody was looking for the plastic
/ rubber cover for a TO-3 transistor that was mounted on the outside of a
rear panel of a piece of Tek equipment.



There is one of these on Ebay at the moment for a Buy It Now price of $4.75.
There are 3 available at

http://www.ebay.com/itm/Tektronix-200-0692-00-Transistor-Cover-/361316897529
?hash=item54202a52f9:g:xjYAAOSwpdpVdyUo



I have no connection with the seller, etc.

Dennis Tillman W7PF

Re: TDS 380 calibration and vertical scale problem

David DiGiacomo
 

On Tue, Feb 9, 2016 at 4:49 PM, <david.wilson92@...> wrote:
I wish I knew as getting that schematic is proving very difficult to find. I did come up with Microck as the manufacturer though, their website can be found here http://microckt.com/. I dug around in the manual and that is what I found below, make sure you have enough horizontal space to view this properly

Comp Number tektronix number Name / Description Mfr Code Mfr Part Number
A13AT205 165–2565–00 MICROCKT,HYBRID:1MEG OHM ATTEN/PREAMP TK2601 165–2565–00
A13AT206 165–2565–00 MICROCKT,HYBRID:1MEG OHM ATTEN/PREAMP TK2601 165–2565–00
You are misinterpreting that... the description is "Microcircuit,
Hybrid". They were made by Tektronix.

Re: 7904 - Very Dim Trace

 

Do you know what kind of phosphor the CRT has ?Some phosphors are optimized for photographic applications instead of the human eye.Make sure the 10X horiz mag is not turned on; it can dim the trace significantly if the trigger rep rate is low.If the timebase has variable holdoff, that can affect it too. HankC, Boston WA1HOS

[Non-text portions of this message have been removed]

Re: 2465 scopes with poor vertical linearity

 

Make sure that you don't have a vertical deflection plate lead disconnected.Does the symptom affect all channels ?Is the beam finder switch stuck ?
 HankC, Boston WA1HOS

[Non-text portions of this message have been removed]

Re: TDS 380 calibration and vertical scale problem

David Wilson
 

I wish I knew as getting that schematic is proving very difficult to find. I did come up with Microck as the manufacturer though, their website can be found here http://microckt.com/. I dug around in the manual and that is what I found below, make sure you have enough horizontal space to view this properly

Comp Number tektronix number Name / Description Mfr Code Mfr Part Number
A13AT205 165–2565–00 MICROCKT,HYBRID:1MEG OHM ATTEN/PREAMP TK2601 165–2565–00
A13AT206 165–2565–00 MICROCKT,HYBRID:1MEG OHM ATTEN/PREAMP TK2601 165–2565–00

Re: looking forward to ebay shipment for about 5 weeks now

 

Hi Christoph,

This is why it is so problematic for Ebay transactions that cross national
boundaries.

Maybe Customs is waiting on you to pay the VAT.

Contact the seller. Explain the situation (nicely) to him and ask him to
contact his local postmaster if he sent it by Canada post. Indicate to the
seller that you will notify PayPal as a formality to protect your interests
if it has not arrived (again, do it nicely). That should help coax the
seller to contact his postmaster to track the shipment. The postmaster will
sometimes be able to tell that it arrived into Customs in your country and
if Customs has been sitting on it.

You should also ask the seller for a copy of all the shipping receipts so
you can verify he sent it to the right address. The receipts will indicate
how much he paid for the shipping and that will give you an idea of the
weight and size of what he shipped to you. It should correspond to what you
would expect for a large box weighing 20 to 30 kilos.

Dennis Tillman W7PF

-----Original Message-----
Sent: Tuesday, February 09, 2016 1:48 AM
Subject: [TekScopes] looking forward to ebay shipment for about 5 weeks now

I bought some Tek Modules on Ebay recently (a TM5006A W/ DM505, PG502,
PS502-1, DM501A, PS503A, PG506), to be precise, on Dec. 18th, 2015 and the
items have not yet arrived here (in Germany). I'm getting a bit nervous. The
seller had one negative feedback in his history (saying "scam") but the
other items he sold seemed okay and he is still selling a lot of items
related to Tek equipment. He also sent me a CanadaPost tracking number that
existed and seemed to match the shipping date. But that's all I could find
out.
I don't want to cite his full name here but his name has got to do with
avionics and region :). Maybe he is reading here anyway :)

I know that items often take a couple of weeks and one cannot track them
once they had left the originating country. But when I miss the Paypal
deadline to put up a claim, it would be odd either.

Christoph
------------------------------------
Posted by: christophkukulies@...
------------------------------------

Re: TDS 380 calibration and vertical scale problem

Ed Breya
 

OK there's the relay, now how about the circuitry around it? Ed

Re: 7904 - Very Dim Trace

 

On Tue, 09 Feb 2016 18:03:45 +0000, you wrote:

On Tue, 9 Feb 2016 at 12:00 jimmcintyre22@... [TekScopes] <
TekScopes@...> wrote:

At this point, I'm pretty sure I made a big mistake using carbon resistors
in my homebrew HV probe. I had no idea how bad their voltage coefficient
was.
I wonder if you can't use the existing HV divider in the scope to get a
better reading. If you measure the resistance of the resistors in the
divider with the scope off, and then measure the voltage over the low
element of the divider, wouldn't that give you the voltage (assuming the
scope's divider is sane)?
That could work but measuring the actual divider resistance will not
be trivial and we do not know its voltage coefficient of resistance
without testing it with a calibrated high voltage source. All we can
really determine is if the cathode voltage is in regulation by
measuring the output of U1635. If we assume the voltage divider is
exactly as marked, then that makes the cathode voltage -50V * 29.65M /
500k = -2965V. The error from the input bias current is cancelled by
R1637 but the input offset voltage and offset bias from the
operational amplifier add about another +/-10 volts to that. There
are some direct substitutions for U1635 which would lower that error
by an order of magnitude but what is important is that the cathode
voltage remain stable over time and temperature; its absoluate value
is not critical.

You could make a simple high voltage probe with the appropriate
resistor(s) for less than $10 with a total error within 1.5%. To do
better than that would cost as much as buying a used high voltage
probe like a Fluke 80k-6 off of Ebay and they are only good to 1%.