Date   

RAMS opening

Dave Brown
 

RAMS asked me to post this message.

RAMS store will be reopening on Thursday, October 21st, 2021. The days and hours will be as they were before, first and third Thursday each month, 2-4pm for the public.

We've gotten a lot of inquires at the museum about RAMS. We are not associated, just good neighbors.

Dave


2445B vertical non-linearity other issues.

Robin Szemeti
 

I have a 2445B that has gone a bit odd recently.

Ch2 and to a lesser extent CH1 have developed vertical non-linearity. Put a sine wave through it and it is obvious, a sort ot cross-over distortion around the centre of the tube .. Moving the trace around with the vertical position control it appears the distortion stays stationary and the trace moves through it. I also noticed the text had moved vertically off the bottom of the display ... and if I move CH1 or CH2 beams into the upper part of the display, the text starts to jitter and shake .. this does not happen with CH3 or 4

This non linearity does not affect CH3 or 4 so I think the vertical amp U600 is fine, and swapping with a good spare I have did not improve it. I'm beginning to suspect the channel switcher IC, U400 ... do the symtoms sound typical?


Re: 492 fan replacement - speed control?

Tom Gardner
 

On 04/10/21 03:14, Edward Prest wrote:
I might just run the new fan continously at a reduced speed to keep it quiet . It's not going to run outside in the sun.
What would be a sufficient speed?

Not knowing the thermal characteristics of a running 492, nor the requirements, I chose to use:

* a fan with the highest flow I could find in that size
* fiddled with the circuit to ensure it always ran, even if slowly
* ran at full speed at what I considered to be a relatively low "maximum"
temperature

Perfect? Certainly not!

I hope that will be adequate, especially considering the undemanding max temperatures in this part of the world :)

The fan I used was a Sunon, 24 V dc, DC Axial Fan, 60 x 60 x 25mm, 53.5m³/h, 3.1W
https://uk.rs-online.com/web/p/axial-fans/0126284

Better would be to make a tiny board using a LM35 temp sensor and a LM358 comparitor driving a FET or darlington to switch the fan on and off. The temperature should stabilize nicely.
What would be the single preset temperature?

I would guess that having a, say, 3 degree hysteresis at the fan would lead to a larger hysteresis in a distant component.
At least having a constant flow would reduce that effect.

The original fan board has the 5v crowbar - not to be removed!
Just so! I re-used those components, and tested it :)


Re: 492 fan replacement - speed control?

Edward Prest
 

I might just run the new fan continously at a reduced speed to keep it quiet . It's not going to run outside in the sun.

Better would be to make a tiny board using a LM35 temp sensor and a LM358 comparitor driving a FET or darlington to switch the fan on and off. The temperature should stabilize nicely.

The original fan board has the 5v crowbar - not to be removed!


Re: 7D14 Plugin

n4buq
 

The plugin has several faults. It doesn't count by 1's and I think that's due to the LSB being stuck high. RESET causes it to display a 0001 instead of 0000 for, I presume, the same reason. GATE functions also don't work. I was in the process of looking at waveforms from the input to the output when I found the lack of Q' on that flipflop. I'm not 100% sure it's the flipflop but I can't find anything else that would be taking that output low with no input signal present.

I think I'm going to give it a good cleaning before doing much else. I'm getting tired of working on dirty plugins (and the D/U for that matter). I keep wanting to disassemble everything and give it all a good bath.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Harvey White" <madyn@dragonworks.info>
To: "tekscopes" <TekScopes@groups.io>
Sent: Sunday, October 3, 2021 8:09:09 PM
Subject: Re: [TekScopes] 7D14 Plugin
Or find the data on the 7D14 upgrade, and get another 7D14, then use the
"bad" one for a source of parts.  Now you know what to look for, and I
have to go see if I have any.....

Harvey


On 10/3/2021 9:03 PM, n4buq wrote:
Thanks for that info, Håkan. Looks like I have yet another doorstop. :( I'm
going to need more doors...

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "zenith5106 via groups.io" <hahi=telia.com@groups.io>
To: "tekscopes" <TekScopes@groups.io>
Sent: Sunday, October 3, 2021 4:43:55 PM
Subject: Re: [TekScopes] 7D14 Plugin
On Sun, Oct 3, 2021 at 03:20 PM, n4buq wrote:

the pictures on the TekWiki page shows a different circuit board
In the early 7D14's U329 was a Tek made IC, 155-0046-00. That became obsolete
and from B050000 156-0377-00, MC12090P,
was used instead on a redesigned circuit board. The new IC was not a direct
replacement so for replacement a Parts
Replacement kit, 050-0638-00, which contained only the redesigned complete
circuit board, 670-0993-01 had to be used.
The original 155-0046-00 was not used in any other instruments.

/Håkan







Re: 7D14 Plugin

n4buq
 

BTW, does anyone know why a specially-designed IC was needed? I presume it was to meet the frequency specification but I don't know.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "zenith5106 via groups.io" <hahi=telia.com@groups.io>
To: "tekscopes" <TekScopes@groups.io>
Sent: Sunday, October 3, 2021 4:43:55 PM
Subject: Re: [TekScopes] 7D14 Plugin
On Sun, Oct 3, 2021 at 03:20 PM, n4buq wrote:


the pictures on the TekWiki page shows a different circuit board
In the early 7D14's U329 was a Tek made IC, 155-0046-00. That became obsolete
and from B050000 156-0377-00, MC12090P,
was used instead on a redesigned circuit board. The new IC was not a direct
replacement so for replacement a Parts
Replacement kit, 050-0638-00, which contained only the redesigned complete
circuit board, 670-0993-01 had to be used.
The original 155-0046-00 was not used in any other instruments.

/Håkan



Re: 7D14 Plugin

Harvey White
 

Or find the data on the 7D14 upgrade, and get another 7D14, then use the "bad" one for a source of parts.  Now you know what to look for, and I have to go see if I have any.....

Harvey

On 10/3/2021 9:03 PM, n4buq wrote:
Thanks for that info, Håkan. Looks like I have yet another doorstop. :( I'm going to need more doors...

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "zenith5106 via groups.io" <hahi=telia.com@groups.io>
To: "tekscopes" <TekScopes@groups.io>
Sent: Sunday, October 3, 2021 4:43:55 PM
Subject: Re: [TekScopes] 7D14 Plugin
On Sun, Oct 3, 2021 at 03:20 PM, n4buq wrote:

the pictures on the TekWiki page shows a different circuit board
In the early 7D14's U329 was a Tek made IC, 155-0046-00. That became obsolete
and from B050000 156-0377-00, MC12090P,
was used instead on a redesigned circuit board. The new IC was not a direct
replacement so for replacement a Parts
Replacement kit, 050-0638-00, which contained only the redesigned complete
circuit board, 670-0993-01 had to be used.
The original 155-0046-00 was not used in any other instruments.

/Håkan





Re: 7D14 Plugin

n4buq
 

Thanks for that info, Håkan. Looks like I have yet another doorstop. :( I'm going to need more doors...

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "zenith5106 via groups.io" <hahi=telia.com@groups.io>
To: "tekscopes" <TekScopes@groups.io>
Sent: Sunday, October 3, 2021 4:43:55 PM
Subject: Re: [TekScopes] 7D14 Plugin
On Sun, Oct 3, 2021 at 03:20 PM, n4buq wrote:


the pictures on the TekWiki page shows a different circuit board
In the early 7D14's U329 was a Tek made IC, 155-0046-00. That became obsolete
and from B050000 156-0377-00, MC12090P,
was used instead on a redesigned circuit board. The new IC was not a direct
replacement so for replacement a Parts
Replacement kit, 050-0638-00, which contained only the redesigned complete
circuit board, 670-0993-01 had to be used.
The original 155-0046-00 was not used in any other instruments.

/Håkan



Re: 465B Horizontal Sweep help

Robert Simpson
 

Update,
I ordered a new 2.5k trimmer cap and temporarily soldered it to the top of the remnants of the original trimmer R4275. With a jumper in place of Q4475, I now have horizontal trace. Next need to figure out the problem with the blanking circuit that controls Q4475.


Re: 492 fan replacement - speed control?

Tom Gardner
 

On 04/10/21 00:37, Edward Prest wrote:
I was reading the 49x notes doc as I have a dying fan. I have found a good 30cfm fan , 24v, but no temperature speed control. How hard would it be to take the existing 3 phase fan output and filter it with some sort of simple rc filter to throttle a new fan? Whzt about rf noise. New dc fans seem to be brushless - can they even be throttled? Is this approach wrong headed.
I used a small DC fan that fitted into the same foam rubber mounts as the original fan, thus minimising vibrations.

I created a crude circuit that used a thermistor to sense the temperature, and an LM317 voltage regulator to vary the voltage across the fan, and hence its speed.

The board was the same size and shape as the original board, and had the same external connections, so it didn't require any physical external changes.

It works in that it varies the speed according to temperature, but I don't know whether the temp-airflow curve is the same.

No, I'm not proud of it, and it is manhattan construction rather than a pukka PCB :)


492 fan replacement - speed control?

Edward Prest
 

I was reading the 49x notes doc as I have a dying fan. I have found a good 30cfm fan , 24v, but no temperature speed control. How hard would it be to take the existing 3 phase fan output and filter it with some sort of simple rc filter to throttle a new fan? Whzt about rf noise. New dc fans seem to be brushless - can they even be throttled? Is this approach wrong headed.


Re: Tek 577 Curve Tracer for Sale

Bob Albert
 

I don't see how to PM you.  I am at bob91343@yahoo.com.
Bob K6DDX

On Sunday, October 3, 2021, 02:52:14 PM PDT, k28collier via groups.io <kevin.collier=warnerbros.com@groups.io> wrote:

Hi Group - I have a Tek 577 D1 for sale in the Los Angeles Area......91602 to be more exact.  I got this at auction and repaired the +12V/5v power supply section.  I was going to make it into a vacuum tube curve tracer but now realize it is too big for my small shop.
Here's a link to a small video showing basic functionality.  https://youtu.be/XLGyza0lfLk

It still needs additional cleaning up of the basic instrument and switches but seems to function and has no HV transformer problems.  I am not keen on shipping this beautiful piece of gear so looking for someone local.  Please PM me if you'd like to make an offer.  Thanks! - Kevin


Tek 577 Curve Tracer for Sale

k28collier
 

Hi Group - I have a Tek 577 D1 for sale in the Los Angeles Area......91602 to be more exact. I got this at auction and repaired the +12V/5v power supply section. I was going to make it into a vacuum tube curve tracer but now realize it is too big for my small shop.
Here's a link to a small video showing basic functionality. https://youtu.be/XLGyza0lfLk

It still needs additional cleaning up of the basic instrument and switches but seems to function and has no HV transformer problems. I am not keen on shipping this beautiful piece of gear so looking for someone local. Please PM me if you'd like to make an offer. Thanks! - Kevin


Re: 7D14 Plugin

 

On Sun, Oct 3, 2021 at 03:20 PM, n4buq wrote:


the pictures on the TekWiki page shows a different circuit board
In the early 7D14's U329 was a Tek made IC, 155-0046-00. That became obsolete and from B050000 156-0377-00, MC12090P,
was used instead on a redesigned circuit board. The new IC was not a direct replacement so for replacement a Parts
Replacement kit, 050-0638-00, which contained only the redesigned complete circuit board, 670-0993-01 had to be used.
The original 155-0046-00 was not used in any other instruments.

/Håkan


Re: Looking for WaveStar WSTR31 Version 1.3

Andrew
 

Sorry, I was referring to Archive.org. Wasn’t sure if it was ok to post software links here, but here we go: https://archive.org/details/TEK_WSTR31U_V1.2.2

Enjoy =D


Re: Looking for WaveStar WSTR31 Version 1.3

Bruce Lane
 

Which archive? KO4BB's site?

    A link would have been helpful...

On 03-Oct-21 02:27, Andrew wrote:
For anyone that is interested--I did happen to find version 1.2.2 and it's up on the Internet Archive now.



--
Bruce Lane, ARS KC7GR
kyrrin@bluefeathertech.com
"Quando Omni Flunkus Moritati" (Red Green)


7D14 Plugin

n4buq
 

I'm in the process of troubleshooting my 7D14. As I received it, it will only count in free-run mode and gate operations do not work.

While troubleshooting, I found that U329 doesn't appear to be working properly. It appears the "1" output is working but the "0" output is stuck high. Functionally, this appears to be an SR flip-flop but the package is very odd (e.g. a large, round IC with a circular heatsink that appears to be held in place with a nylon ring that might be removeable with a spanner wrench, etc.).

Web search for that P/N hasn't revealed anything but the interesting part is that the pictures on the TekWiki page shows a different circuit board and different part for U329 than what I have (shows a DIP-packaged IC instead of the large round one in mine). Furthermore, picture of that board on the TekWiki page shows a P/N of 670-0993-00 but the pictures in the manual shows a P/N of 388-1825-00. Did Tek change the design or are the pictures on the TekWiki page for a different version of this counter?

Anyone know about this?

Thanks,
Barry - N4BUQ


Re: Looking for WaveStar WSTR31 Version 1.3

Andrew
 

For anyone that is interested--I did happen to find version 1.2.2 and it's up on the Internet Archive now.


Looking for a few mechanical parts for a 317

Scott Johnson
 

Hello All,
I am in the process of spiffing up my 317 and need a couple of the fastener assemblies that hold the side covers on.
The are the same on most older instruments, and consist of the slotted screw, the washer , and the nylon wing nut.
I need two of these assemblies.
By the way I have several boxes of parts for 500 series instruments if anyone is looking.

regards,
Scott W7SVJ


Re: Right Angle Power Cords For 2465 Oscilloscopes

Mark Vincent
 

Jeff,

Shielded cables have a type of metal shield over the wires like a microphone cable. The shield is foil type or a braid. On the outside it will have "shielded" on it. The shield is also called a drain wire. It is connected to the ground wire. This keeps out interference. Switching supplies are where they are best used to reduce radiation from the cord to other things. It also keeps out external noise. Using a shielded cord on things with a power transformer can be done. I like shielded cords on things that are three wire. The additional capacitance of the cord reduces the noise level. The shield makes the cable a bit larger, stiffer and more expensive. Computer repair places may have these shielded cords around.

I had to do heavy shielding and filtering in things when the older Verizon box that is at the house was here. That was the worst white noise generator made! The ground wire it had went to a screw that was in the plastic case connected to nothing inside. The circuit had no shield. It would interfere with anything, TV circuits, am, fm, sw, VHF, etc.. Anyone with a mobile telephone was jammed within several meters of that box. Unplugging it would allow someone to have a signal. The shielded cables usually attenuated the noise enough to make things work right. At times I had to put in filtering in things to further reduce the noise that box generated. R-F filtering had to be added to things you normally would not need it in to keep that noise out, e.g. audio. Even the electrolytics made a difference. The lowest ESR types made a difference enough that they had to be used. I tested things to determine how to get that noise out or low enough. A couple of turn L pickup 1/4 meter away from the box to a scope would make the screen look like TV raster (agc control too far either way or video output removed to crt). The 7104 at the fastest sweeps was almost raster looking. The vertical was in the tenths of volt per division with the pickup I used and near full height of the screen. That scope has a shielded mains cord. That box finally was changed out earlier this year. They admitted to the noise that box made and how it was not FCC approved when they were changing it out with the new one that is far better. It is nice now that I do not have to turn the telephone line off when r-f noise must be eliminated when working on something.

Mark

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