Date   

Re: Type 106

Eric
 

I kept the gr connectors on the fast rise but good quality bnc is good to 4
Ghz so I changed the high output one for ease of hookup. Just needed a
quick adaptor plate.

Eric

On Thu, Mar 18, 2021, 10:02 AM Stephen <stephen.nabet@gmail.com> wrote:

Yesterday I picked up from eBay a Type 106 High Amplitude (120v into
50ohm), Fast Rise Square Wave Generator.
I haven’t received it from Germany yet.
I’m wondering whether I should keep the original low reflection GR-874,
and get a GR-874 to BNC adaptor for it, or convert it to BNC’s. I know the
Fast Rise outputs are mounted on the board, probably to further minimize
the reflection, and are harder to convert.
But wouldn’t a BNC adapter, like a conversion to BNC, defeat the purpose,
and add reflection??

Also, it comes in a rather unusual (to me) case, which does appear to be
stock.

https://groups.io/g/TekScopes/album?id=261997






Type 106

Stephen
 

Yesterday I picked up from eBay a Type 106 High Amplitude (120v into 50ohm), Fast Rise Square Wave Generator.
I haven’t received it from Germany yet.
I’m wondering whether I should keep the original low reflection GR-874, and get a GR-874 to BNC adaptor for it, or convert it to BNC’s. I know the Fast Rise outputs are mounted on the board, probably to further minimize the reflection, and are harder to convert.
But wouldn’t a BNC adapter, like a conversion to BNC, defeat the purpose, and add reflection??

Also, it comes in a rather unusual (to me) case, which does appear to be stock.

https://groups.io/g/TekScopes/album?id=261997


Re: SMB Adaptor (again)

Stephen
 

Thanks Jeff,

I haven’t ordered anything yet. I’m waiting for my list of needed stuff to get a bit bigger and order everything at the same time. I’ll keep that in mind though. Thank you.


Re: SMB Adaptor (again)

Stephen
 

The SMA are much larger then the SMB, aren’t they??


Re: SMB Adaptor (again)

 

The SMB-BNC cables I ordered from Amazon arrived and they do fit my DC505, but they are very tight, almost impossible to disconnect using just my fingers. Where/are the outputs on the DC505 infrequently used?

The specific cables that I bought (KNARCO) seem to be out of stock now, but I see another (even less expensive) listing from LIVISN. The odd company names (and the price) make me suspect that these are Chinese sellers, but I have no proof of that. The cables I ordered came somewhat inexplicably triple bagged: first a small bubble wrap bag, enclosed in a sealed anti-static bag, and finally in a blue and white ziplock bag.

-- Jeff Dutky


Re: TDS544A with strange display #photo-notice

durechenew@...
 

Thanks Siggi; your conclusion is matching mine. I'll go the board and make some real measurements (till now, mostly in my mind - with some few exceptions).
TT


Re: TM500 Board Set- 3D printed plastic face plate

 

Did anyone in Europe (or better UK) get the inner front panel 3D printed? If so did you have to get more than one printed? If so I'd be interested to buy one of them? If no-one has spares what material is recommended for 3d printing and what units should I use for the STL file?

Thanks
David----

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Jared Cabot via groups.io
Sent: 17 February 2021 15:31
To: TekScopes@groups.io
Subject: Re: [TekScopes] TM500 Board Set- 3D printed plastic face plate

Ok, I've corrected the dimensions in the manual now.
The PCB's were made from the latest revision, but I pulled the dimensions from the 3D files just before that final tweak.
The manual has been updated with the correct dimension, so f you download v1.5, it should all match up now.


Re: 485 super weak brightness control

Ondrej Pavelka
 

So..... I changed following diodes for BAV21 and there was no change to the
behaviour.
CR1651
CR1646
CR1664
CR1666
CR1660
CR1656
CR1652

No intensity control and no grid bias control. I was desperate but then I
noticed there's another one hiding covered by a cap CR1663 and that was the
one!! Now I have nice sharp trace and working intensity control!

I need to calibrate it, I can get good image but as soon as I change either
of the intensity controls it gets blurry.


Now with the HV supply sorted I can progress further with the list of
problems

Vertical amp Channel 1 is in top condition all LEDs working lightbulb
working
Vertical amp channel 2 has the 1x LED gone and lightbulb gone. Otherwise
cleaning brought it back to 100% working order.

Horizontal A sweep

Works flawlessly from 5second to about 10uS. From 5uS the image starts ever
so slightly moving to the right but I still get enough to fill the full
screen when I use the horizontal position control because there is a
reserve, at 10nS I pretty much run out of the reserve. I can still center
it to have full 10 divisions but there is no reserve at all.
The 5 2 and 1nS settings are not working at all.



Horizontal B sweep.

I don't get any B sweep from 5s to 20ms then I get good B sweep for 10mS to
0.2uS
0.1uS to 10nS is showing only first 4 divisions from the left
5 2 and 1 ns is working correctly.

The delay time position potenciometer is not in best shape, it gets stuck
quite often and needs to be wiggled about to move it further. The latching
is somehow damaged.


Power supply fan.

Is quite picky, it sometimes runs and sometimes it does not.

On Wed, 17 Mar 2021, 19:17 Ozan, <ozan_g@erdogan.us> wrote:


Trust me it's the phones auto correct turning opamp into obama :)
I know I was just kidding. I also had my share of funny auto correct
stories.

I think I had the timebase measurements AC coupled and there was no
change
in level. I haven't checked the DC. I will do that tomorrow when I'm back
at the workshop.
The goal is to find if sweep trigger is not coming (no gate) or sweep
trigger comes but sweep doesn't happen. DC levels are important to
understand the state of the sweep circuit.

At the end most likely it will be a dirty switch. You can make a good
guess which one by looking sheet <10> and see which switches only change in
the last three settings. However, we can also pinpoint which one by
electrical debug.

BAV21 looks OK as a replacement, it has better specs in some areas. The
swing at the restorer input is ~ 100Vpp max, so the diodes in the grid bias
area will not see more than 200V. Close to max spec but could be a good
initial debug step. If others see a problem please chime in.

Ozan







Re: Tek 2230 psu story (work in progress)

Pitpat
 

Update, the new t948 has arrived but not before i managed to burst another componet, a zener diode this time (1N475A) 6.2 voltage reference in the inverter section seems to be the only fault this time but since im at it ill replace all the electrolitic caps with some new good low esr ones. BTW the fail (open not shorted) of the said diode seems to result in a similar cycle of the one induced by the crowbar circuit (witch it was removed on my scope) but with the neon spark-gaps that do not operate.


Re: PS 5010 troubleshooting (no negative, erratical display)

 

Hi Steve,

thanks for your insights. I did understand what you said about the front/rear switch, but I could not altogether follow what you said about the voltage and current ramps. In particular, the error-condition (i.e. erratical blinking of pos and neg supply), when present, was permanent. It only disappeared once I got a certain amount of current flowing. And finally it turned out it was related somehow to the hi/lo switch.

Realigning the supplies was straightforward and easy to do... well designed, as I said. Currently I have two PS5004 precision supplies in the frame. Both turned out OK, so I started the alignment. But theres a weird thing, something I've never seen before: a corse and fine alignment pot that is realigned several times on later steps! Usually a pot is aligned and you don't touch it anymore. Do you know anything about that module, too?

cheers
Martin


Re: Message from your fearless (foolish?) leader

goodappl
 

Hi Dennis,

Please add my best wishes to Marian for her speedy and complete recovery. Was happy to hear that she finally got the much needed and delayed hip replacement. I'm sure the outcome will eventually be very good, but sorry for the pain she has to endure in the meantime, and the extra duties you have to take on. I know how busy you were already. You have both been such gracious hosts every time I've been to your place over the years. (Guess George and I won't be returning any more to tune at Westminster Chapel, as he's finally totally retired.) Hopefully things will be getting back to normal soon!

All the best,
Tom G.


Re: Type 111 Pretrigger Pulse Generator

Tim Phillips
 

From Tim P (UK)
Hi; This is the mod to supply double pulse output. See Hakan's page

http://hakanh.com/dl/kits.htm

I think it was used to set up the loop gain on samplers.

Tim

On Thu, 18 Mar 2021 at 03:16, Sean Turner <sdturne@q.com> wrote:

Hey all,

I was wondering if anyone knows of any factory mods that were done on the
Type 111? I have an example that has a significant divergence from the
schematic in the manual, namely around the fixed increment control. It's a
little circuit mounted on an aluminum tab with a small ceramic strip on the
inside and three socketed transistors on the outside, and there is a pot
installed instead of the switch. I can't discern that this control has any
effect on anything, and it is definitely not present in any scan of the
manual or any pictures of the internals of other Type 111s.

Furthermore, it is factory quality assembly work, so I'm assuming it's
either factory or someone who was really careful.

I put three photos of the circuit here (
https://groups.io/g/TekScopes/album?id=261991). I annoted one of them to
show the four places where the mystery circuit is wired into the main PCB.

Thanks!

Sean

Sean






Re: PS 5010 troubleshooting (no negative, erratical display)

ditter2
 

Hello Martin,

I designed the analog circuitry in the PS5010, although that was nearly 45 years ago…

The front/rear switch not only selects the output terminals, but the remote sense inputs for voltage regulation as well. So if the switch is intermittent, you many have one of the sense inputs open, which would explain the lack of regulation.

The power supply goes through voltage and current ramps when the output is cycled to protect the relay from damage in fault conditions. The loop balance monitors are not monitored during this ramp cycle.

I have found those switches commonly used in TM500/5000 and 5100 series remain reliable if operated in a very clean environment, but have problems when there is dust in the air. They are not sealed, and lubricated with grease. Dust will get into the grease and make its way into the contact surface, which causes them to become intermittent. Also, the grease cakes up when it gets dirty, making the switch spring return not operational.
Steve


Type 111 Pretrigger Pulse Generator

Sean Turner
 

Hey all,

I was wondering if anyone knows of any factory mods that were done on the Type 111? I have an example that has a significant divergence from the schematic in the manual, namely around the fixed increment control. It's a little circuit mounted on an aluminum tab with a small ceramic strip on the inside and three socketed transistors on the outside, and there is a pot installed instead of the switch. I can't discern that this control has any effect on anything, and it is definitely not present in any scan of the manual or any pictures of the internals of other Type 111s.

Furthermore, it is factory quality assembly work, so I'm assuming it's either factory or someone who was really careful.

I put three photos of the circuit here (https://groups.io/g/TekScopes/album?id=261991). I annoted one of them to show the four places where the mystery circuit is wired into the main PCB.

Thanks!

Sean

Sean


Re: Free 547 and plug ins (pick up in Boston area)

Christopher Galbraith
 

Hi again all--the 547 and plug ins have found a new home. Thanks! --Chris

On Wed, Mar 17, 2021 at 8:38 AM Christopher Galbraith <
christopher.galbraith@gmail.com> wrote:

Hi folks,

I'm getting ready to move and need to find a good home for a 547 with 1A1
and B plug ins. Dusty, but stored in a low humidity storage area. It worked
the last time I powered it on a few years ago, but suspect it will need
some TLC. Complete, with power cord but no probes or cart. It originally
came from the EE dept. at MIT (stenciled on the side and property tag on
front). I need to have it picked up by 3/28, currently in Belmont, MA.

Please email me directly with any interest/questions.

Thanks!

--Chris (christopher.galbraith@gmail.com)


Restore CD for TLA714

Sandra Carroll
 

Hi,
I just finished repairing a TLA714 LA which had a Bad HD. Installed Windows 2000 and got TLA software from XDEV. LA was perfectly fine otherwise.
I am looking for anyone who has a copy of the TLA714 Restore CD with the OS and TLA software whos either willing to provide a ISO of the CD or I'll purchase from you if you prefer?

I've got an original Doc CD coming but just don't have the restore CD

TIA to anyone who can help

Sandra


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

 

Sorry guys. They sold for $46.66 with shipping included!
Listing number was: 362763553704


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

 

I don't have a 519, but I figured some of the members would :)
There are several listings for 125 ohm GR (search for "GR874" but most sellers don't know the difference between 125 and 50 ohm connectors).
174325617026
363163812256
222979950687
223426804340
161839191197
333654464808

Unfortunately, I think someone got the adapters Dennis is referring to (don't see them listed).
Better luck next time!


Re: TDS544A with strange display #photo-notice

Siggi
 

Hey TT,

I groused through the block diagram and the schematics a bit more, and
here's my hypothesis for how the VGA and the LCS interfaces relate. This is
pure speculation, but I think everything below fits the facts that you've
observed, the TLC34075 datasheet and the schematic.

U2011 (on diagram <24>) gets the VGA timing and 5 bits per pixel data from
U2101. It buffers up a batch of 4 VGA pixels, and then writes them to the
VRAM (U400 et al on diagram <23>). The TLC34075 reads pixel data from the
VRAM 4 pixels at a time, where each pixel is padded out to 8 bits by a zero
bit and the two LCS_CSEL0/1 lines.
The line scan frequency of the TLC34075 is exactly three times the line
scan frequency of the VGA interface, and it displays each VGA line three
times in rapid succession, once for each color in RGB (in some order).
Padding the pixel data with the LCS_CSEL1/0 lines allows the TLC34075 to
pick out the appropriate part of the palette for the current primary color
of the pixel displayed, against the LCD shutter selected for the current
replay of the VGA line.

Now a good question might be why 5 bits per pixel, and I don't know the
answer to that. One way to cut it might be 3 bits of color, one bit of
intensity, and 1 bit of (text?) overlay. This could again be shoehorned
into providing the display we observe through the right palette data.

This might help narrowing down why your intensity modulation seems to be
pixel clocked. If you look at the ordering of the data lines into and out
of the VRAM, you'll see that they get interleaved into the pixel inputs on
the TLC4075. I don't know why this is, but maybe you need to be focusing on
the address and data lines for the VRAM. It might be as simple as a
high-resistance or floating VRAM data line, possibly an "intensity" bit.

Happy hunting,
Siggi

On Wed, Mar 17, 2021 at 5:20 PM durechenew via groups.io <durechenew=
yahoo.com@groups.io> wrote:

Last few days I just read everything in manual from start to end,
sometimes backwards, to try to understand as good as possible how this
scope works (CPU and display board).
Siggi was right about signal on Ch4 having some issues.
Three new clips in Dropbox (name starts with 3., then 4. and 5.; all after
CLEAR MENU pressed):
https://www.dropbox.com/sh/8oo1j0060in4l8v/AAB-FuSaEN7gnGhagvCjWwjta?dl=0
The first one shows scope screen; Ch1 and Ch4 on display, no input signal
on any channel; on Vertical, button Ch1 pressed and Ch1 light ON; nothing
unusual (disregard fuzziness, it's angle of camera)
The second one shows scope screen; Ch1 and Ch4 on display, no input signal
on any channel; on Vertical, button Ch4 pressed and Ch4 light ON; some
vectors on Ch4 show in red; if I switch to dots (in Display), some dots
will show red.
The third one shows VGA monitor screen; Ch1 and Ch4 on display, no input
signal on any channel; on Vertical, button Ch4 pressed and Ch4 light ON;
same information as above but on VGA monitor - no red vectors (not obvious,
but to naked eye Ch4 is blue on VGA too).
Previous idea stays (that everything is correct, up to the point where
information is split between VGA path and Video path). Not ready to make
assumptions, I'll wait a little, so the stuff settles in my mind; it seems
everyday is clearer, but still some way to go...
TT






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

Sean Turner
 

Dennis,

Is there a link to this listing? I am certainly interested.

I actually have two of the boxes (actually, mine are walnut, according to the label on the bottom) and am only missing one or two of the impedance matching adapters. The second one I found local to me, and while the box is unfortunately in poor shape, it contains a total of TEN brand new reeds for the calibration step generator!

Sean

On Wed, Mar 17, 2021 at 10:19 AM, Dennis Tillman W7pF wrote:


Hi Charles and Dave and Sean,
The RATIO of the diameter of the INSIDE of the OUTER conductor to the OUTER
diameter of the INSIDE conductor and the dielectric constant of the medium in
between the conductors determines the impedance of a coaxial cable (or
adapter). This is why, if you look inside the gold plated end, you will see
the center conductor is a completely different size than the 50 ohm center
conductor.

Tek gold plated the 125 ohm ends of these GR connectors to distinguish them
from the 50 ohm end. ANY gold plated GR connector is a 125 ohm impedance and
guaranteed to be part of the original set of 50 ohm to 125 ohm adapters and
tools which came with every 519 in a beautiful mahogany box. I had one of
those boxes many years ago. My friend Barrie Gilbert bought it from my friend
who had most of the adapters that went with it when Barrie came to my house to
pick up his 519.

A picture of the outside of the mahogany box is at
https://w140.com/tekwiki/wiki/519#/media/File:519_adaptkit2.jpg
Unfortunately I no longer have a picture of the inside of the box with the
adapters.

By the way, the price he is asking for these adapters ($12 each) is
ridiculously cheap. DO NOT HESITATE to use his BUY IT NOW option. There are
many, many others who will take the extra ones from you for twice what you pay
for these four.

Dennis Tillman W7pF

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