Date   

Re: Switch retainers for 7000 series plug ins

 

Hi Martin,

The switch you need is going to be extremely hard to find for several reasons:
* Tek started using these switches late in the lifetime of the 7000 series. So they are not very common.
* The switch holder is riveted to the PC board so it is unlikely that this part would be saved.
* The sliding contacts on the removable part are extremely tiny and they fall out when you remove that part of the switch so those will get lost unless you are very careful to save them too.

For those reasons I think it is extremely unlikely that you will find what you need. Instead you need to consider an alternative to save that valuable plugin:
* Live with it the way it is. I rarely use the External Trigger input. Any signal requiring an external input trigger to a 7B10/7B15 is going to be able to drive 50 ohms. So the smart thing to do would be to hard wire this switch to the 50 ohm input impedance on the PC board. If you ever need 1Meg impedance use the 7B10 as your External Trigger instead.
* Clark Foley's suggestion to put a piece of wire through the rivet hole is a good one except in this case it might be difficult because of where the rivet holes are located.
* A piece of busbar or stiff wire about 0.050" in diameter might work to secure the switch holder to the PC Board if it is a tight fit in the hole and can be wedged into it.
* Careful application of some epoxy may also work.
* I have some tiny Philips head self-tapping screws (0.060" dia.) which might fit provided you had a Philips screwdriver that had a PH00 tip. It might require some patience to get them in the hole on the switch holder and then into the hole on the PC board. These self-tapping screws have the advantage that they can be inserted from the component side of the PC board without removing the PC Board and if they work you are done.
*If you can get the rivet out entirely then there are more options such as slightly larger machine screws with nuts for 0.085" holes. I have those too. You would need to get to the other side of the PC board to put the nuts on.

I can send you two of both the machine screws and nuts and the self-tapping screws.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Martin Whybrow
Sent: Thursday, February 06, 2020 10:53 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Switch retainers for 7000 series plug ins

Yes, the switches in the FG504 are not the same type unfortunately.





--
Dennis Tillman W7PF
TekScopes Moderator


Re: Switch retainers for 7000 series plug ins

Martin Whybrow
 

Yes, the switches in the FG504 are not the same type unfortunately.


Re: Switch retainers for 7000 series plug ins

Dave Trainor
 

Sorry, auto-correct must have fixed that for me. I meant FG 504. And
from what I am hearing its a different type of switch, however I have a
set of the FG 504 switches. My apologies for sending it as FG400.

Thanks,
Dave N8ZFM

On 2/5/20, 5:23 PM, "TekScopes@groups.io on behalf of Martin Whybrow"
<TekScopes@groups.io on behalf of martin@...> wrote:

Dave, I can't locate any information on the FG400; can you point me in
the right direction please?




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Re: Switch retainers for 7000 series plug ins

Martin Whybrow
 

Dave, I can't locate any information on the FG400; can you point me in the right direction please?


Re: Switch retainers for 7000 series plug ins

Martin Whybrow
 

Actually it's the single gang switch that selects 1MOhm or 50Ohm impedance on the external trigger. The switch itself is fine, it's the grey plastic latch that retains it to the PCB that's damaged.


Re: TDS3000B USB floppy emulator

Holger Lübben
 

Hi Oz!

I've checked my mails and I have to correct myself.
It was the manufacturer who answered my technical questions.
You can reach them under sales@...

They had a minimum order quantity of 10 items so at the end I bought it somewhere on aliexpress.

Holger


Re: TDS820 help

Dave Casey
 

Have you tried running Signal Path Compensation (SPC) to see if the scope
will null it out for you?

Dave Casey

On Wed, Feb 5, 2020 at 10:45 AM george gonzalez <grg2gonzalez@...>
wrote:

I bought an old TDS820 with a somewhat blown second channel.

It “works” and seems to be mighty speedy, somewhere near spec, anyway it’s
faster than my Jim Williams rise time checker, however but has a large and
intermittent negative offset of about 1 volt.

Are there any known common fault modes for this that are easily
repairable? Like hitting the input stage with a small hammer? I can
almost null the offset out with the offset adjust.


Thanks,

George





Re: 2465B - Weak Readout Intensity

Mark Litwack
 

I replaced a CRT on a 2465 and have done exactly as Chuck suggested with only adjusting the various vertical and horizontal pots. It took about 10 minutes.

The only suggestion I have is to use the cursors to do the alignment. Once for each axis, set them to show a value that is the same as the full graticule range, and then adjust the pots (gain and center) to make the cursors land on the edge graticule lines.

I also adjusted the transient response, but that isn't difficult either if you have a pulse generator with a fast edge.

-mark

On Tue, Feb 4, 2020 at 05:57 PM, Chuck Harris wrote:


Really, the answer is yes.

The new CRT will certainly have different gain for its deflection
plates, its control grid will have a different curve to match.

The geometry plates will be a little different.

Tilt, and Y axis rotation will certainly be different.

And, the transient response is going to be different, because the
vertical deflection plates are really a lumped transmission line.

The manual says full calibration if you replace a major assembly...
the CRT applies.

That stuff said, you might be able to satisfy your own needs by
doing the CRT calibration, and the rotations.

The pots for vertical gain and centering, and Hx1, Hx10, and H-center
could be done without additional test equipment.

Worth a try... most won't notice the transient response... until
they get to the high frequencies.

-Chuck Harris


Re: 2465B - Weak Readout Intensity

Lawrance A. Schneider
 

On Tue, Feb 4, 2020 at 04:58 PM, <flanneltuba@...> wrote:


SUCCESS!
Congratulations!


TDS820 help

george gonzalez <grg2gonzalez@...>
 

I bought an old TDS820 with a somewhat blown second channel.

It “works” and seems to be mighty speedy, somewhere near spec, anyway it’s faster than my Jim Williams rise time checker, however but has a large and intermittent negative offset of about 1 volt.

Are there any known common fault modes for this that are easily repairable? Like hitting the input stage with a small hammer? I can almost null the offset out with the offset adjust.


Thanks,

George


Re: TDS3000B USB floppy emulator

Oz-in-DFW
 

Holger,
Which reseller did you work with?
Oz


Re: Knob and help.

James R. Bartlett
 

Thanks Tom,.
I would like to see the files if it is not too much trouble.
Appreciate the reply and the offer.
Be good to get a good knob or fix up the other one.
Thanks again

Regards
Jim

On Wed, 5 Feb 2020 at 13:03, Tom Gardner <tggzzz@...> wrote:

When I had a 475 with missing V/div legend, I

* created my own legend
* printed it on transparent plastic
* used UHU "rubber solution glue" to stick it behind the plastic on the
knob

Send me an email if you want the files I used for the legend


On 05/02/20 11:04, James R. Bartlett wrote:
Greetings to the group,
Regular reader but seldom poster needs help.
I am working on a 475 at the moment.
I am in need of a vertical sensitivity knob as the lettering on the
Channel
2
one is very badly worn. Anyone have a spare one?
Also have a problem with the voltage indication changing on the Channel
knob.
When using a x10 probe sometimes it will not switch to the x10 lamp.
moving the probe around at the BNC connector sometimes it comes on,
Probes
are mainly Tek ones
Some switchable others are fixed x10.
any thoughts ?
Many thanks
Jim
Ei2BB




Re: Knob and help.

James R. Bartlett
 

Thanks Colin.
Ok on the knobs, yes they are pretty scarce. QService are out of stock.
THe probes do have the necessary pin, they are mainly TEK switched x1/x10
It appears to be a poor contact somewhere as they work sometimes.
Thanks for the reply.
regards
Jim


On Wed, 5 Feb 2020 at 13:17, Colin Herbert via Groups.Io <colingherbert=
blueyonder.co.uk@groups.io> wrote:

Hi,

If you are referring to the Volts/Div knobs, then it is possible to
repair the lettering on them. I did it some time ago with a knob on a 468;
those knobs are unobtainium because of the extra positions and black
background. I think I used a gel-pen.

With regard to the lamps behind the knob skirts which light up the
appropriate settings for X1 and X10 probes, to begin with, the probe must
have the sensor pin to contact the extra ring on BNC connector. It can be
checked that the switching and bulbs are OK by connecting between the extra
ring and ground with an 11 k ohm resistor. If this doesn't work, there is a
possible broken connection inside, but space is limited in there and it
isn't easy to access the input BNC connectors. I also recall that the lamps
will not be lit unless the appropriate channel is selected to be active.

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of James
R. Bartlett
Sent: 05 February 2020 11:05
To: Tekscopes@groups.io
Subject: [TekScopes] Knob and help.

Greetings to the group,
Regular reader but seldom poster needs help.
I am working on a 475 at the moment.
I am in need of a vertical sensitivity knob as the lettering on the Channel
2
one is very badly worn. Anyone have a spare one?
Also have a problem with the voltage indication changing on the Channel
knob.
When using a x10 probe sometimes it will not switch to the x10 lamp.
moving the probe around at the BNC connector sometimes it comes on, Probes
are mainly Tek ones
Some switchable others are fixed x10.
any thoughts ?
Many thanks
Jim
Ei2BB








Re: Knob and help.

Colin Herbert
 

Hi,

If you are referring to the Volts/Div knobs, then it is possible to repair the lettering on them. I did it some time ago with a knob on a 468; those knobs are unobtainium because of the extra positions and black background. I think I used a gel-pen.

With regard to the lamps behind the knob skirts which light up the appropriate settings for X1 and X10 probes, to begin with, the probe must have the sensor pin to contact the extra ring on BNC connector. It can be checked that the switching and bulbs are OK by connecting between the extra ring and ground with an 11 k ohm resistor. If this doesn't work, there is a possible broken connection inside, but space is limited in there and it isn't easy to access the input BNC connectors. I also recall that the lamps will not be lit unless the appropriate channel is selected to be active.

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of James R. Bartlett
Sent: 05 February 2020 11:05
To: Tekscopes@groups.io
Subject: [TekScopes] Knob and help.

Greetings to the group,
Regular reader but seldom poster needs help.
I am working on a 475 at the moment.
I am in need of a vertical sensitivity knob as the lettering on the Channel
2
one is very badly worn. Anyone have a spare one?
Also have a problem with the voltage indication changing on the Channel
knob.
When using a x10 probe sometimes it will not switch to the x10 lamp.
moving the probe around at the BNC connector sometimes it comes on, Probes
are mainly Tek ones
Some switchable others are fixed x10.
any thoughts ?
Many thanks
Jim
Ei2BB


Re: Knob and help.

Tom Gardner
 

When I had a 475 with missing V/div legend, I

* created my own legend
* printed it on transparent plastic
* used UHU "rubber solution glue" to stick it behind the plastic on the knob

Send me an email if you want the files I used for the legend

On 05/02/20 11:04, James R. Bartlett wrote:
Greetings to the group,
Regular reader but seldom poster needs help.
I am working on a 475 at the moment.
I am in need of a vertical sensitivity knob as the lettering on the Channel
2
one is very badly worn. Anyone have a spare one?
Also have a problem with the voltage indication changing on the Channel
knob.
When using a x10 probe sometimes it will not switch to the x10 lamp.
moving the probe around at the BNC connector sometimes it comes on, Probes
are mainly Tek ones
Some switchable others are fixed x10.
any thoughts ?
Many thanks
Jim
Ei2BB


Re: TDS3000B USB floppy emulator

Holger Lübben
 

Hi Tom!

My 420A also has a 26 pin interface.
I've talked to a reseller of the emulator and they gave me an overview about the different model numbers.

The main differences were:
- 26 pin or 32 pin interface
- 720KB or 1.44MB
- Accepting a generic USB Stick or accepting only preformatted sticks of the exact target size.

I needed the 26pin interface with a target size of 1.44MB and I wanted to use a generic USB stick - so I ended up with the SFR1M44-DU26.
The interface handshake of a floppy drive is a little bit different from vendor to vendor. And I had no information about how Tek implemented the interface in the 420A.
That's why I had to test several jumper configurations.

The selected emulator works perfectly in my 420A, so there was no need to touch the firmware.

Holger


Re: Stan Griffiths

magnustoelle
 

I am very sorry to hear about Stan's passing. My condolances to his family and friends.

I like to imagine that he has found a place in heaven, sitting close to Deane Kidd, Jim Williams and Bob Pease...

May he rest in peace.

Magnus


Knob and help.

James R. Bartlett
 

Greetings to the group,
Regular reader but seldom poster needs help.
I am working on a 475 at the moment.
I am in need of a vertical sensitivity knob as the lettering on the Channel
2
one is very badly worn. Anyone have a spare one?
Also have a problem with the voltage indication changing on the Channel
knob.
When using a x10 probe sometimes it will not switch to the x10 lamp.
moving the probe around at the BNC connector sometimes it comes on, Probes
are mainly Tek ones
Some switchable others are fixed x10.
any thoughts ?
Many thanks
Jim
Ei2BB


Re: Switch retainers for 7000 series plug ins

 

Hi Martin,
That sounds like the Source INT/LINE/EXT pushbutton switch.
If I am correct it uses three modular 2-piece switches. Those are fragile and have several different failure mechanisms.
There is a Pushbutton Switch repair guide on TekWiki. I believe it discusses how to fix them if you have the parts. That is a big IF.
http://w140.com/tekwiki/images/2/24/Repairing_tek-made_board-mounted_push-button_switches.pdf

I know from experience how to fix them because I have had many of them break.
Each time I first have to find a donor plugin which gets harder and harder.

Good luck,
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Martin Whybrow
Sent: Tuesday, February 04, 2020 2:49 PM
To: TekScopes@groups.io
Subject: [TekScopes] Switch retainers for 7000 series plug ins

I've just acquired a 7854 scope for a nice price; the 7B15 timebase module that was included has a pushed-in switch (S90) which I have found to be due to a broken plastic catch that should be holding the switch onto the PCB. Is there a source for these, other than from a scrap plug in?





--
Dennis Tillman W7PF
TekScopes Moderator


Re: Switch retainers for 7000 series plug ins

Dave Trainor
 

I have a couple of parts TM500 plugins, one a FG400 (witch was sorta
diagonally crushed in shipping) (very sad). It has pushbutton switches,
does anyone know if the pushbuttons are the same? If so I may have 3 or 4
that are not damaged. But I don¹t know not having a 7000 series plugin if
they are even close to the same.

73- Dave N8ZFM

On 2/4/20, 11:16 PM, "TekScopes@groups.io on behalf of Clark Foley"
<TekScopes@groups.io on behalf of clarkfoley@...> wrote:

I had a similar problem on an early 7k prototype mainframe Vert Mode
Select switch. I could not find loose replacement parts.

*******WARNING**********
Collectors and instrument restorers should not read further as I do not
wish to offend!
*******WARNING**********

I drilled two small holes through the PCB and strung some no.24 (AWG)
steel wire through the holes and looped the wire over the tail of the
switch where the nylon clip grabbed the body. Twist the wire together on
the back side of the PCB. Crude but effective. Of course you need to
avoid traces. I would not have the heart to do this to an otherwise
unsuspecting and pristine PCB.

I warned you!




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