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Category: Tektronix 556


Tektronix 556 Dual Beam Oscilloscope Testing: Vertical Bandwidth

Posted by Shaun Merrigan in Electronics, Oscilloscopes, Tektronix 556. Comments Off on Tektronix 556 Dual Beam Oscilloscope Testing: Vertical Bandwidth

27th January

Tektronix 556 Dual Beam Oscilloscope Testing: Vertical Bandwidth

I have been doing some basic testing of my Tektronix 556 Dual Beam Oscilloscope, and I have documented some parts of this process.  I have also captured images of the traces, which I will share here.

Test Setup: Tektronix 556, 1A2 plug-in, Timebase A, Tektronix SG 503 Generator, and Tektronix TG 501 Time Mark Generator

I found the -3db vertical bandwidth of the 1a2/556 to be 65 Mhz, which is to be expected for the 50 Mhz rated 1A2.

 

TM 500 Module with Plug ins

50 kHz Reference Signal 6v peak to peak

5 MHz Sine Wave 6v peak to peak

20 MHz Sine Wave 6v peak to peak

40 MHz Sine Wave 4.8v peak to peak

50 MHz Sine Wave 4.3v peak to peak

65 MHz Sine Wave 4.2v peak to peak

I will continue this testing by investigating the absolute maximum trigger … Read More »


Tektronix 556 Fan Motor Repair Part 2

Posted by Shaun Merrigan in Electronics, Oscilloscopes, Tektronix 556. Comments Off on Tektronix 556 Fan Motor Repair Part 2

22nd January

Tektronix 556 Fan Motor Repair Part 2

In this continuation of Tektronix 556 Fan Motor Repair Part 1, I have removed the motor and mount assembly and disassembled it.  Now I need to figure out the problem and rebuild the motor.

Tektronix 556 Fan Motor Overview, mounted in place

Tektronix 556 Fan Motor removed from mounts.  The Tektronix part number is 147-0029-00.

 

Tektronix 556 Fan Motor removed from mounts.

Tektronix 556 Fan Motor removed from mounts.

The next few images show the disassembled parts of the motor:

Rotor, end bells and bushing assembly

End bell inside, retainer, spring washer felt and bushing.

End bell and bushing assembly

Rotor and spacers

At this point I found several issues by visual inspection:

The original rear bushing had been replaced, probably due to excessive internal wear.
The replacement itself had excessive internal wear and it did not fit in the retainer properly due to its shape.
The replacement … Read More »


Tektronix 556 Fan Motor Repair Part 1

Posted by Shaun Merrigan in Electronics, Oscilloscopes, Tektronix 556, Vacuum Tubes. Comments Off on Tektronix 556 Fan Motor Repair Part 1

19th January

Tektronix 556 Fan Motor Repair Part 1

I was recently fortunate enough to acquire a Tektronix 556 Dual Beam Oscilloscope with many accessories and in good condition.  Unfortunately, the cooling fan on the scope was very loud and more concerning, it emitted an alarming metal on metal contact sound.  After verifying basic operation of the oscilloscope, I decided to repair the cooling fan.  This process is documented in the images and commentary that follow.

Part 1: Removing the Noisy Fan Motor

556 Cooling Module with filter and mesh screen removed.  The fan is connected to the chassis wiring at the ceramic terminal which is circled:

Fan to chassis wiring connection terminal.

 

Inside of cooling module and bottom side of motor (fan blade removed):

Back side of motor (fan blade removed).  This is a 4 pole 1725 rpm (loaded) motor.  It moves a very large volume of air.

An … Read More »


Tektronix 556 Dual Beam Oscilloscope Images

Posted by Shaun Merrigan in Electronics, Oscilloscopes, Tektronix 556, Vacuum Tubes. Comments Off on Tektronix 556 Dual Beam Oscilloscope Images

31st December

Tektronix 556 Dual Beam Oscilloscope Images

What follows is a series of images of my Tektronix 556 Dual Beam Oscilloscope displaying various waveforms.  I am learning about this scope and how to use it.

A brief description of the unit can be found here: Tektronix 556

 

Thanks for reading.

 

Shaun M.



Tektronix 556 Dual Beam Oscilloscope

Posted by Shaun Merrigan in Electronics, Oscilloscopes, Tektronix 556. Comments Off on Tektronix 556 Dual Beam Oscilloscope

5th December

Tektronix 556 Dual Beam Oscilloscope

I had recently the unique opportunity to acquire a complete Tektronix 556 Oscilloscope setup.  This comprised the oscilloscope itself, the matching scope cart, original manual, probes and 12 plug-in units.  This in itself is rare enough, but in addition, this particular scope has the optically desirable blue phosphor CRT and Tektronix C-27 Camera Bezel.   This 50 MHz bandwidth oscilloscope was the state of the art when it was introduced in the mid 1960’s: Tekwiki Tek 556

This will be the first of many posts and updates as I work my way through checking and restoring this beautiful scope.

And now some images:

Thanks!

 

Shaun Merrigan