Shaun Merrigan's Information Pages


Tag: Vintage Electronics


Hickok 209A VTVM Restoration Part 5

Posted by Shaun Merrigan in Electronics, Restoration, Test Equipment. Comments Off on Hickok 209A VTVM Restoration Part 5

1st January

This the fifth part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254. Hickok 209A VTVM Restoration Part 5: Checking the meter movement.

This piece of test gear is all about the large, beautiful meter movement, so I need to determine if this one works properly. What I intend to do is connect the meter to a precision power supply and good ammeter through a current limiting resistor and then determine how the meter responds. The meter is supposed to be a 500uA full scale movement.

Here is the test setup:

Analog Meter Test Instrumentation Setup

A 10kohm limiting resistor is connected in series with the power supply. The power supply is a Tektronix PS5004 and the meter is a Tektronix DM5120.

Full Scale Deflection on the meter was about 497 uA:

Analog … Read More »


Hickok 209A VTVM Restoration Part 4

Posted by Shaun Merrigan in Electronics, Restoration, Test Equipment. Comments Off on Hickok 209A VTVM Restoration Part 4

1st January

This the fourth part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254. Hickok 209A VTVM Restoration Part 4: Restoring the battery holder.

In Part 3 of this series I documented the condition of the D Cell battery holder and outlined the restoration plan for the unit. The first step is to remove and restore the corroded battery holder.

Hickok 209A SN 133254 Corroded Battery Holder

Besides the obvious corrosion, the white connecting wire to the negative terminal was corroded under the insulation from the battery spring clip to the switch solder lug. I replaced the entire length of this wire. The other short wire and ring terminal were cleaned as described below.

Hickok 209A SN 133254 Corroded Terminal Wire

The process I used to restore the battery holder:

Desolder the two … Read More »


Hickok 209A VTVM Restoration Part 3

Posted by Shaun Merrigan in Electronics, Test Equipment. 1 Comment

1st January

This the third part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254. Hickok 209A VTVM Restoration Part 3, corrosion issues and restoration plan.

As mentioned in Part 2 of this series, a visual inspection of the chassis of the 209A revealed a serious corrosion problem with the battery holder. The corrosion had migrated to the bottom of the case but not to the remaineder of the chassis. There were no batteries in the unit when I received it.

Hickok 209A SN 1333254 Battery Holder Corrosion

Hickok 209A SN 1333254 Battery Holder Corrosion

Hickok 209A SN 1333254 Battery Holder Corrosion

Hickok 209A SN 1333254 Battery Holder Corrosion

From the above images, it is clear that the battery holder will require some corrosion mitigation and restoration. Fortunately, it is restorable as the parts are … Read More »


Hickok 209A VTVM Restoration Part 2

Posted by Shaun Merrigan in Electronics, Test Equipment. 1 Comment

1st January

This the second part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254. Hickok 209A VTVM Restoration Part 2, visual inspection.

Outside visual inspection results:

Overall good visual condition outsideMeter appears to move freely and does not stickMeter face is excellent and there are no scratches on the glassMeter bezel is dirty, but does not appear to be corrodedArea of corrosion noted at bottom of caseThe case has some minor paint scuffs and nicks accumulated over the past 60 yearsLine cord appears to be original and looks to be in good conditionHas an original rubber grommet where the line cord enters the caseNo obviously broken parts: lamp, pin sockets, dials are in good conditionHas DC Probe (reads 3.36 Mohms)No AC probe but does have the 4 wire AC probe connectorNo pin tip test … Read More »


Hickok 209A VTVM Restoration Part 1

Posted by Shaun Merrigan in Electronics, Test Equipment. Comments Off on Hickok 209A VTVM Restoration Part 1

31st December

This is the first installment in a multi-part series documenting my restoration of a classic Hickok 209A VTVM. First a description and some images:

This is a Vacuum Tube VoltMeter (VTVM) with a nominal 12 Mohm input impedance and one of the largest mechanical meter movements found on commerical/consumer equipment (viewing area about 8.5 inches diagonal). It was produced from about 1947 (earliest direct evidence) to at least 1961 (catalog reference). One of the units I have has 03-09-55 written in grease pencil on the back of the meter movement. The cost in 1947 was (reportedly) $133 USD which is about $1500 USD in late 2018. In comparison, the HP 410A (a lab grade instrument) sold for $245 USD in 1948 or about $2500 USD in late 2016 dollars. So the Hickok 209A was not aimed at the laboratory … Read More »


Tektronix 7854 Waveform Keyboard Rebuild

Posted by Shaun Merrigan in Electronics, Oscilloscopes, Tech. Comments Off on Tektronix 7854 Waveform Keyboard Rebuild

15th August

Tektronix 7854 Waveform Keyboard Rebuild

From the Tek Wiki:

The Tektronix 7854 Waveform Processing Oscilloscope, introduced in 1980, is a 400 MHz combined analog / digital mainframe in the 7000 series that takes two vertical and two horizontal 7000-series plug-ins. In addition to a conventional analog (real time) scope, it contains an equivalent-time sampling 10-bit digitizer and a programmable waveform processor with GPIB interface. The waveform processor can be programmed using a detachable calculator-style keyboard, using postfix operators (“reverse Polish notation” like HP calculators) that operate on entire waveforms, not just individual numbers.

Tek 7854 Mainframe #2 after cleaning

Tek 7854 Mainframe after cleaning

 

It is to the repair of the detachable keyboard that this post is devoted.  I purchased a keyboard for a reasonable price only to find that some keys were intermittent, and some did not work at all.

Opening up the keyboard showed … Read More »


Tektronix Scope-Mobile Cart Repair Part 3

Posted by Shaun Merrigan in Electronics, Oscilloscopes. Comments Off on Tektronix Scope-Mobile Cart Repair Part 3

7th May

Tektronix Scope-Mobile Cart Repair Part 3

 

Part 1

Part 2 

This is the conclusion to my repair of a Tektronix 202-2 Scope-Mobile Cart.  Recall that the problem was three fractured trunnion mount bosses which rendered the cart useless (and unsafe) under load.  My proposed solution was to place the bosses into compression by putting a 6mm countersunk bolt through the trunnion mount concentric with the existing hole in the boss.  By using appropriate sized washers between the top of the boss and the frame member I ensure that the boss is placed into compression and the frame member is securely clamped.  This avoids the tensile loading which fractured the bosses initially.

 

Trunnion to member closeup with new bolt and washers in place

The holes in the trunnion mount were countersunk to fit the flat head socket bolts:

Countersunk Hole for new bolt

 

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

556 Fan Motor Rear

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

 

Tektronix 556 Fan Motor

Tektronix 556 Fan Motor removed from mounts.

Tektronix 556 Fan Motor

Tektronix 556 Fan Motor removed from mounts.

Tektronix 556 Fan Motor

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

Rotor, end bells and bushing assembly

556 Bushing Assemblies and Rotor

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

556 Fan Motor Bushing Assembly

End bell and bushing assembly

556 Bushing Assembly

Rotor and spacers

556 Fan Motor Shaft … 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:

556 Fan Cooling Module Outside

Fan to chassis wiring connection terminal.

 

556 Fan Cooling Module Fan Connections

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

556 Fan Motor Underside

Back side of motor (fan blade … Read More »


New Vacuum Tube Box Scans

Posted by Shaun Merrigan in Electronics, Vacuum Tubes. Comments Off on New Vacuum Tube Box Scans

6th January

New Vacuum  Tube Box Scans

I have uploaded several new vacuum tube box scans including Philco, Canadian General Electric, Wards, and Hitachi (Hit-Ray):

 

Wards Tube Box_3

Wards Tube Box_2

Wards Tube Box_1

Philco Tube Box_4

Philco Tube Box_3

Philco Tube Box_2

Philco Tube Box_1

Motorola Small Tube Box_4

Motorola Small Tube Box_3

Motorola Small Tube Box_2

Motorola Small Tube Box_1

Lafayette Tube Box_4

Lafayette Tube Box_3

Lafayette Tube Box_2

Lafayette Tube Box_1

Hitachi Tube Box_4

Hitachi Tube Box_3

Hitachi Tube Box_2

Hitachi Tube Box_1

CGE Radiotron Tube Box_2 (4)

CGE Radiotron Tube Box_2 (3)

CGE Radiotron Tube Box_2 (2)

CGE Radiotron Tube Box_2 (1)

Wards Tube Box_4

 

Thanks,

 

Shaun M.