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Hey guys,
While visiting the features of a different time base (a 7B92) I realized it has the possibility to display the delayed time base in alternate mode with the MTB, with a "trace Separation" knob, as it became common place in later oscilloscopes and which I particularly missed on my previous 464 scope, and keep missing on the 7623A + 7B53A I currently have.
This feature, I wasn't aware it was possible on the 7k series, due to the Vertical <-> Horizontal flavoring of the plugin compartments so, how could a horizontal plugin displace the signal vertically?
After seeing the feature on the 7B92 I was happy to see that there IS a provision for an auxiliary vertical input at the horizontal compartment... and that it is there exactly to allow that kind of feature.
Immediately I started wondering if that could be something that could be added to a "regular" horizontal plugin (specifically thinking about mine, the 7B53A).
It crossed my mind than, the 7B53A has a very convenient control (already on the panel) which could and - after second thoughts - indeed can be used for that...
That is the "Variable" control.
Well, the 7B53A is already designed to accommodate in this control, 3 different controls... Variable MTB, Variable Dly'd time base, and Variable Hold-off.
So... Why not adding a small board inside the 7B53A, to add the Alternate time base functionality (and I`m thinking of the space reserved to the : Option 5, Composite Video Sync board).
This functionality would work whenever the user chose to move the Variable control pin header to this board...
By leaving the Variable control in its detent, the functionality of the 7B53A would remain unchanged... and by taking it out of its detent, it would automatically engage the Alternate mode, and the variable control would become the "Trace Separation" control.
Added some analog switches (if feasible) or mini relays, one can even retain the original "Var functionality", making it slave to the Delayed time base functions...
If no delayed time base function would be engaged, the Var control could be routed to the 7B53A pin headers, and it could perform exactly as intended originally (as Var MTB, Var Dly'd TB or Var HoldOff depending on which header it would be connected).
As soon as the Delay'd TB function would be engaged (by pulling and turning the Dly'd TB knob, the new circuit would kick in and route the Var Knob to the "Alternate TB functionality".

What do you think of this idea? Isn't it something that Tek could have added to the 7B53A (as an option)?

Do you think it would work?

What about the MIX mode? Should I make the MIX mode slave to the Alternate functionality? or Vice-versa? (I dare you to know what I mean).

I`m looking forward moving this project ahead... It seems quite feasible and I`m not sure yet if I resort to bare bones TTL or CMOS logic, or if I throw in a small uC and do all on software (somewhat overkill for what it needs to be done, but sure enough it would consume less energy and would be easier to build).

Hope to hear your feedback.

Fabio

On Wed, Oct 3, 2018 at 03:54 PM, Fabio Trevisan wrote:

What do you think of this idea? Isn't it something that Tek could have added
to the 7B53A (as an option)?

That would be the same as or similar to 7B53A mod 178H.
I placed a copy of the description here www.hakanh.com/dl/temp/7B53Amod178H
but I have to warn you, it is extremely poor quality due to a poor original print and
microfiche original but with a little good will and fantasy most of it could be read.

/H?kan

On Wed, Oct 3, 2018 at 09:04 PM, zenith5106 wrote:

I placed a copy of the description here www.hakanh.com/dl/temp/7B53Amod178H

Sorry, the link should be www.hakanh.com/dl/temp/7B53Amod178H.pdf

/H

Hakan,

Ah Hah! I knew it was too obvious for not having been thought of before!
On the other side...I`m kind of sad now. I was hoping that I had an original idea :-(.

At least, to save my face, for what I understood, they crippled the X1-X10 button to enable the Alternate mode...So I think my idea is better in that respect.

It's possible that I can implement my idea with basically the same circuit, just adapting it to use the "Var" control (and its detent switch) and thus, avoiding to cripple the X1-X10 functionality.

Thanks for the heads up.

Rgrds,

Fabio
P.S. Any chance to obtain a better scan of this microfiche?

On Wed, Oct 3, 2018 at 09:39 PM, Fabio Trevisan wrote:

P.S. Any chance to obtain a better scan of this microfiche?

That would be if someone else has better sheet. With mine it was impossible
to get a clear view even on the reader. Usually they are better than this.

/H?kan

Hello Hakan,

It occurred to me to google for "7B53A MOD178H" and look what came up...

This PDF (in TekWiki) not only includes the 178H, but also other mods to the 7B53A.
And the scan is very readable.

Upon further reading, I understood that it doesn't actually cripples the functionality of the x1-x10 (which would be silly), but moves this function to the "MIX" mode button (pull VAR control).
Indeed, the MIX mode loose its place and gets deleted, but anyone would agree that the MIX mode becomes completely obsolete when you have the Alternate time base functionality.
The mod then, uses the X1-X10 panel real estate to add a dual potentiometer, for the trace separation and also to control the intensity of the Dly'd sweep / Intensified portion (which is a really nice feature, but requires the addition of a dual potentiometer to the panel, which I don't think I can do, aesthetically speaking.
Therefore, I`ll probably make a mod of the mod, to implement its design as much as possible, but not adding the Dly'd Intensity control, and using the "Var" control for the trace separation, as it was my original plan.

Kindest Regards,

Fabio