Topics

A Drop-In Replacement for the U800 (2400 scopes)


Ram
 

Dear 24xx enthusiasts,
I have built a prototype of a drop-in replacement for the U800 chip found in the 2400 series scopes. You already know the story of the U800s so I don't need to say much. A video showing how it works in all modes (X1, X10, B-Sweep etc) is now up on YouTube. I plan to offer it as a product by the end of Q3 2020. Please do view it and let me have your questions and suggestions. Thanks!
https://www.youtube.com/watch?v=2FZGAFm1ESg
Cheers - Ram


Szabolcs Szigeti
 

Hi Ram,

Wow! This is a very exciting project and shows really cool results.
Unfortunately this means that I will need look around and buy a 2465 so now
I can be sure that u800 problem wont hit me :-)

Szabolcs


Ram <ramkumar.ramaswamy@...> ezt írta (időpont: 2020. jún. 12., P,
8:09):

Dear 24xx enthusiasts,
I have built a prototype of a drop-in replacement for the U800 chip found
in the 2400 series scopes. You already know the story of the U800s so I
don't need to say much. A video showing how it works in all modes (X1, X10,
B-Sweep etc) is now up on YouTube. I plan to offer it as a product by the
end of Q3 2020. Please do view it and let me have your questions and
suggestions. Thanks!
https://www.youtube.com/watch?v=2FZGAFm1ESg
Cheers - Ram




Ondrej Pavelka
 

Don't worry Shabolcs, another hybrid like U400 could die on you.

On Fri, 12 Jun 2020, 10:14 Szabolcs Szigeti, <szigiszabolcs@...>
wrote:

Hi Ram,

Wow! This is a very exciting project and shows really cool results.
Unfortunately this means that I will need look around and buy a 2465 so now
I can be sure that u800 problem wont hit me :-)

Szabolcs


Ram <ramkumar.ramaswamy@...> ezt írta (időpont: 2020. jún. 12., P,
8:09):

Dear 24xx enthusiasts,
I have built a prototype of a drop-in replacement for the U800 chip found
in the 2400 series scopes. You already know the story of the U800s so I
don't need to say much. A video showing how it works in all modes (X1,
X10,
B-Sweep etc) is now up on YouTube. I plan to offer it as a product by the
end of Q3 2020. Please do view it and let me have your questions and
suggestions. Thanks!
https://www.youtube.com/watch?v=2FZGAFm1ESg
Cheers - Ram






Shirley Dulcey KE1L
 

It looks promising, Ram. These should help us repair some currently dead
scopes.

On Fri, Jun 12, 2020 at 6:38 AM Ondrej Pavelka <info@...>
wrote:

Don't worry Shabolcs, another hybrid like U400 could die on you.

On Fri, 12 Jun 2020, 10:14 Szabolcs Szigeti, <szigiszabolcs@...>
wrote:

Hi Ram,

Wow! This is a very exciting project and shows really cool results.
Unfortunately this means that I will need look around and buy a 2465 so
now
I can be sure that u800 problem wont hit me :-)

Szabolcs


Ram <ramkumar.ramaswamy@...> ezt írta (időpont: 2020. jún. 12., P,
8:09):

Dear 24xx enthusiasts,
I have built a prototype of a drop-in replacement for the U800 chip
found
in the 2400 series scopes. You already know the story of the U800s so I
don't need to say much. A video showing how it works in all modes (X1,
X10,
B-Sweep etc) is now up on YouTube. I plan to offer it as a product by
the
end of Q3 2020. Please do view it and let me have your questions and
suggestions. Thanks!
https://www.youtube.com/watch?v=2FZGAFm1ESg
Cheers - Ram








George Kerber
 

I will take two, maybe more! Nice work. - George

On Thu, Jun 11, 2020 at 11:09 PM Ram <ramkumar.ramaswamy@...> wrote:

Dear 24xx enthusiasts,
I have built a prototype of a drop-in replacement for the U800 chip found
in the 2400 series scopes. You already know the story of the U800s so I
don't need to say much. A video showing how it works in all modes (X1, X10,
B-Sweep etc) is now up on YouTube. I plan to offer it as a product by the
end of Q3 2020. Please do view it and let me have your questions and
suggestions. Thanks!
https://www.youtube.com/watch?v=2FZGAFm1ESg
Cheers - Ram




Tam Hanna
 

Will post on my Instagram shortly!


Tam

--
With best regards
Tam HANNA

Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at https://www.instagram.com/tam.hanna/


Paul Amaranth
 

Is this an update of the Thomas Lafay implementation? Or is this a
new design entirely? That didn't seem to go anywhere but at least
the design files are available.

Paul

On Fri, Jun 12, 2020 at 12:38:20PM +0200, Ondrej Pavelka wrote:
Don't worry Shabolcs, another hybrid like U400 could die on you.

On Fri, 12 Jun 2020, 10:14 Szabolcs Szigeti, <szigiszabolcs@...>
wrote:

Hi Ram,

Wow! This is a very exciting project and shows really cool results.
Unfortunately this means that I will need look around and buy a 2465 so now
I can be sure that u800 problem wont hit me :-)

Szabolcs


Ram <ramkumar.ramaswamy@...> ezt írta (időpont: 2020. jún. 12., P,
8:09):

Dear 24xx enthusiasts,
I have built a prototype of a drop-in replacement for the U800 chip found
in the 2400 series scopes. You already know the story of the U800s so I
don't need to say much. A video showing how it works in all modes (X1,
X10,
B-Sweep etc) is now up on YouTube. I plan to offer it as a product by the
end of Q3 2020. Please do view it and let me have your questions and
suggestions. Thanks!
https://www.youtube.com/watch?v=2FZGAFm1ESg
Cheers - Ram









!DSPAM:5ee35b3a21251357132188!
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix/Linux - We don't do windows


Andy Warner
 

Nice job, keep us posted with your progress as you push them through
manufacture.

On Fri, Jun 12, 2020 at 1:09 AM Ram <ramkumar.ramaswamy@...> wrote:

Dear 24xx enthusiasts,
I have built a prototype of a drop-in replacement for the U800 chip found
in the 2400 series scopes. You already know the story of the U800s so I
don't need to say much. A video showing how it works in all modes (X1, X10,
B-Sweep etc) is now up on YouTube. I plan to offer it as a product by the
end of Q3 2020. Please do view it and let me have your questions and
suggestions. Thanks!
https://www.youtube.com/watch?v=2FZGAFm1ESg
Cheers - Ram



--
Andy


Martin Whybrow
 

Great job Ram, I can see that being a popular module when you manage to perfect the layout.


Bob Koller <testtech@...>
 

Looks good! Will it pass the CAL01 procedure?


victor.silva
 

On Fri, Jun 12, 2020 at 10:41 AM, Paul Amaranth wrote:


Is this an update of the Thomas Lafay implementation? Or is this a
new design entirely? That didn't seem to go anywhere but at least
the design files are available.

Paul
I would ask the same thing. Although in the Youtube video it is stated that x-y mode works, the Lafay implementation did not support X-Y mode.
Also, some of the output in the back of the scope were not supported by the Lafay design.

I would take one for experimentation and testing (depending on cost). I have several tubes of Tek U800s so I have enough for years to come.

--Victor


Ram
 

Dear folks,
Thank you very much for the encouraging responses and questions. I will indeed keep you posted on the progress as I take it to manufacture. I am planning to launch this for sale by the end of Q3 2020. The PCB layout and design are in the third iteration and this video was essentially the result of my attempts to fine-tune the performance to an acceptable level before finalizing the design and layout. Of course I do not claim it works as well as the original U800 but the hope is that you find this useful enough to allow you to stow away the original for a rainy day and use this replacement board on noncritical occasions.

1. "Will it pass the CAL01 procedure?" From what I can see, as long as the same adjustment controls used in CAL01 continue to work with the replacement board, you can carry through the procedure to completion. And that was the aim, which is why the "drop-in" tag. The only adjustment that the current prototype in the video does not have is the "TRANS RESP" trimmer but the next version of the PCB has it.

2. "Is this an updated version of the Thomas Lafay implementation? Or a new design entirely?" I was indeed inspired by the magnificent effort by Thomas Lafay. However I had some difficulties when I tried to get it to work, and I felt a more comprehensive and at the same time a more compact implementation was possible. Conceptually of course they are very similar - I cannot claim my design is "entirely new". For example I used the same transistor topology as in the Tek 2232, which the Lafay design also did (though the transistors themselves are different). However there are important differences. Foremost, it attempts to provides all of the functional modes - including XY which is not in the former. Secondly, in doing so, it makes use of all the adjustment controls on the main board itself. Thirdly, I found that the 500ps/div needs special attention - which is why you have a TRANS RESP trimmer on the main board to specifically adjust the gain of the 500ps/div mode. My design adds a few extra smarts for get the 500ps/div speed. The layout is of course completely different - the Lafay implementation is a much larger PCB which needs you to replace a few parts on the main board to be able to accommodate it.

But again, many thanks are due to Mr. Lafay for the original effort and the inspiration!

Best - Ram


@0culus
 

Very neat effort, Ram. It seems to me that once you get a final version with all SMD components and also eliminate the socket, the performance will be nearly indistinguishable from the original. Will be keeping an eye on this for sure.

PS--good taste in signal generators...I love my 8640B. Yeah it's not synthesized but it makes very high quality signals and who doesn't enjoy twiddling knobs?

Sean

On Thu, Jun 11, 2020 at 11:09 PM, Ram wrote:


Dear 24xx enthusiasts,
I have built a prototype of a drop-in replacement for the U800 chip found in
the 2400 series scopes. You already know the story of the U800s so I don't
need to say much. A video showing how it works in all modes (X1, X10, B-Sweep
etc) is now up on YouTube. I plan to offer it as a product by the end of Q3
2020. Please do view it and let me have your questions and suggestions.
Thanks!
https://www.youtube.com/watch?v=2FZGAFm1ESg
Cheers - Ram


Li Gangyi
 

Watching this with interest. A possibility of U800 failing is why I didn't
get my hands on a 2465B when I saw one around my area.

On Sat, Jun 13, 2020 at 12:19 PM Ram <ramkumar.ramaswamy@...> wrote:

Dear folks,
Thank you very much for the encouraging responses and questions. I will
indeed keep you posted on the progress as I take it to manufacture. I am
planning to launch this for sale by the end of Q3 2020. The PCB layout and
design are in the third iteration and this video was essentially the result
of my attempts to fine-tune the performance to an acceptable level before
finalizing the design and layout. Of course I do not claim it works as well
as the original U800 but the hope is that you find this useful enough to
allow you to stow away the original for a rainy day and use this
replacement board on noncritical occasions.

1. "Will it pass the CAL01 procedure?" From what I can see, as long as the
same adjustment controls used in CAL01 continue to work with the
replacement board, you can carry through the procedure to completion. And
that was the aim, which is why the "drop-in" tag. The only adjustment that
the current prototype in the video does not have is the "TRANS RESP"
trimmer but the next version of the PCB has it.

2. "Is this an updated version of the Thomas Lafay implementation? Or a
new design entirely?" I was indeed inspired by the magnificent effort by
Thomas Lafay. However I had some difficulties when I tried to get it to
work, and I felt a more comprehensive and at the same time a more compact
implementation was possible. Conceptually of course they are very similar -
I cannot claim my design is "entirely new". For example I used the same
transistor topology as in the Tek 2232, which the Lafay design also did
(though the transistors themselves are different). However there are
important differences. Foremost, it attempts to provides all of the
functional modes - including XY which is not in the former. Secondly, in
doing so, it makes use of all the adjustment controls on the main board
itself. Thirdly, I found that the 500ps/div needs special attention -
which is why you have a TRANS RESP trimmer on the main board to
specifically adjust the gain of the 500ps/div mode. My design adds a few
extra smarts for get the 500ps/div speed. The layout is of course
completely different - the Lafay implementation is a much larger PCB which
needs you to replace a few parts on the main board to be able to
accommodate it.

But again, many thanks are due to Mr. Lafay for the original effort and
the inspiration!

Best - Ram




victor.silva
 

U800 failing is not the end of the world for a 2465B. Firstly it is not as common as internet lore as lead people to believe.
In my opinion there are other hybrids that fail much more frequently.
I would say at least 200 2465B have passed through my hands and I have seen about three** U800 failures, but during that
time I have seen at least 20 Z-Axis hybrid failures.

The difference is that U800 is soldered in, but to replace it means removing the main board (A1), unsoldering a 24 pin DIP and finding a replacement U800.
For a company that sends 2465B to Cal house, this will be deemed beyond repair and scrapped (or ebayed).
For a hobbyist, this is perfectly do-able.

**Note that I am not counting the U800 made by MAXIM, which is complete garbage - these are typically found in the newest 2465Bs (say after s/n B064xxx)
I believe Tek sold off their foundry to MAXIM, and the magic ingredient was apparently lost on the U800.

--Victor


Jim Ford
 

I remember Maxim and Tektronix doing a joint venture in the 1980's or 1990's called MaxTek.Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: "victor.silva via groups.io" <daejon1=yahoo.com@groups.io> Date: 6/13/20 9:30 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] A Drop-In Replacement for the U800 (2400 scopes) U800 failing is not the end of the world for a 2465B.  Firstly it is not as common as internet lore as lead people to believe.In my opinion there are other hybrids that fail much more frequently.I would say at least 200 2465B have passed through my hands and I have seen about three** U800 failures, but during thattime I have seen at least 20 Z-Axis hybrid failures.The difference is that U800 is soldered in, but to replace it means removing the main board (A1), unsoldering a 24 pin DIP and finding a replacement U800.For a company that sends 2465B to Cal house, this will be deemed beyond repair and scrapped (or ebayed).For a hobbyist, this is perfectly do-able.**Note that I am not counting the U800 made by MAXIM, which is complete garbage - these are typically found in the newest 2465Bs (say after s/n B064xxx)I believe Tek sold off their foundry to MAXIM, and the magic ingredient was apparently lost on the U800.--Victor


John Williams
 

I haven’t done that elegant repair to any 2465B scopes. I was terrified of tackling that much of a repair. In my case I cut the old chip off the board by clipping each pin of right against the chip. Then I soldered the new chip onto the pin remnants sticking out of the board. This left the chip a little bit above the boards surface, so I worried that the heat from the chip would cook it. I installed a cpu fan on top of the chip. Not elegant but it worked.


victor.silva
 

Some of the U800s are repairable especially the ones that fail by the horizontal creeping slowly to the left as the scope warms up.

I posted a thread back in 2013 about three U800s that I baked:
https://groups.io/g/TekScopes/message/82320

Three of them were resurrected. In fact I put one of them in my bench 2465B in 2013 and it's still working fine to this day!

--Victor


victor.silva
 

Ram,

I would love to get one of your U800 modules when you release the final version.
I would be happy to independently evaluate it and post the results here.

Thanks,
Victor


Ram
 

Victor: Thank you...I hope to be ready soon to make use of your offer to evaluate the replacement module.
Sean: Yes indeed, twiddling 8640B knobs is even more pleasurable when you've been able to get the plastic gears inside replaced with brass ones so you know they can take a lot more twiddling.
Best - Ram