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It is 'well known' that the 7D20 draws too much power from a standard 7603;

-----Original Message-----
From: Tim Phillips
Sent: Thursday, October 11, 2018 7:04 AM
Subject: [TekScopes] 7000-series power-hungry plug-ins

From Tim P (UK)
It is 'well known' that the 7D20 draws too much power from a standard
7603; is there a definitive list of power-hungry plug-ins, and which
'scopes they can be used in ?
IIRC this also applies to some of the 7L- SpecAnal plug-ins.
thanks
Tim

Hi Tim,
I have used a 7D20 in several 7603s I have. All of the plugins could not exceed a well-defined set of power supply voltage, current and power specifications the mainframes had available. Meeting these requirements was sometimes the most difficult aspect of a design.

I suggest you calibrate your 7603 power supplies (and take a look at the power supplies in the 7D20 as well) and then try using the 7D20 again.

I would not disagree with you there were many power hungry plugins. Many of those came along in the mid-1970s and they used power hungry digital logic. The power needs of this type of circuitry was not something the designers of the 7K series could anticipate when they were finalizing the basic requirements of the product line.

The 7D20 is power hungry but it should work if the scope is working properly.

Another really good example would be the 7D01 Hardware Logic Analyzer which is almost entirely made of extremely power hungry ECL logic. It was the only way to reach the 100MHz speed necessary to troubleshoot complex digital circuits.

The 7D02 Microprocessor Logic Analyzer is also a power hungry plugin. It is packed full with TTL which is not as bad as ECL but still needs lots of power. None of the more lower power TTL families were available yet in the numerous logical building blocks that plugin needed. The product engineer on the project told me all the things they tried to lower the power requirements so it would meet the mainframe specs. He was disgusted by the entire process.

The triple wide Spectrum Analyzer plugins are also power hungry.

Dennis Tillman W7PF

On 12 Oct 2018, at 06:01, Chuck Harris <cfharris@...> wrote:

If I remember correctly, the original 7603 had a
wimpy linear supply, and no fan. Later revisions
used a more robust linear supply, and a quiet little
internal fan.

The 7603 of the later years was the scope intended
for the 7D20, 7L family.... it was the big screen that
made it desirable.

The 7904 (plain) cannot handle the 7L13. It will send
the supply into tick mode. Not the usual tick mode,
but one that was very weird sounding.

The 7904A handles it just fine... but then it has a big
supply and a loud fan.

-Chuck Harris

Dennis Tillman W7PF wrote:

Hi Tim,
I have used a 7D20 in several 7603s I have. All of the plugins could not exceed a well-defined set of power supply voltage, current and power specifications the mainframes had available. Meeting these requirements was sometimes the most difficult aspect of a design.

I suggest you calibrate your 7603 power supplies (and take a look at the power supplies in the 7D20 as well) and then try using the 7D20 again.

I would not disagree with you there were many power hungry plugins. Many of those came along in the mid-1970s and they used power hungry digital logic. The power needs of this type of circuitry was not something the designers of the 7K series could anticipate when they were finalizing the basic requirements of the product line.

The 7D20 is power hungry but it should work if the scope is working properly.

Another really good example would be the 7D01 Hardware Logic Analyzer which is almost entirely made of extremely power hungry ECL logic. It was the only way to reach the 100MHz speed necessary to troubleshoot complex digital circuits.

The 7D02 Microprocessor Logic Analyzer is also a power hungry plugin. It is packed full with TTL which is not as bad as ECL but still needs lots of power. None of the more lower power TTL families were available yet in the numerous logical building blocks that plugin needed. The product engineer on the project told me all the things they tried to lower the power requirements so it would meet the mainframe specs. He was disgusted by the entire process.

The triple wide Spectrum Analyzer plugins are also power hungry.

Dennis Tillman W7PF

I successfully run 7L14s in a 7603 mainframe. I have two of these 7L14 and both are OK. The notable exception of course is the lack of push button illumination on some buttons because the 7603 doesn't have a suitable 5V Lamp supply in-built (you have to add your own circuit into the 7603).

Regards

Nigel G8AYM

-Chuck Harris

PS, thanks to H?kan for the 7904 power supply capacity note.

Regarding this pdf of 7000 series currents ..... I am unfamiliar with the terms Foldback currents and ULU.
Can some-one please explain??

-Chuck Harris

PS, thanks to H?kan for the 7904 power supply capacity note.

In regulated supplies, there are often over current protection
circuits that are used in lieu of fuses. These circuits reduce
the voltage from the power supply in an attempt to reduce the
current, and the power dissipation, to something that the supply
can safely survive. This is called current foldback.

The Tektronix power supplies for the most part all have this
capability.

-Chuck Harris

Okay, understand that now. I have played with/built many linear supplies, but none with much protection circuitry.
Thank you, Chuck.
Cheers,
Ian

In regulated supplies, there are often over current protection
circuits that are used in lieu of fuses. These circuits reduce
the voltage from the power supply in an attempt to reduce the
current, and the power dissipation, to something that the supply
can safely survive. This is called current foldback.

The Tektronix power supplies for the most part all have this
capability.

-Chuck Harris