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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

Looking to repair a Feiler TS-9 Electronic Vacuum tube Volt-Ohm-Milliammeter

Evidentially it was offered in a factory wired form or kit form. I would like to find/buy the kit instructions and or schematic for this unit. I can't seem to find a schematic or any information other than it was made in 1950 was offered wired for $48 and in kit form for $22. Its quite nice for its age and with some rewiring and tweeking the 4 pots I would be able to bring it back to its former glory or at least good enough so I can use it on circuits in old radios and such. Any help would be appreciated. More than willing to buy the information that I need.
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My VTVMs use more modern tubes and a solid state rectifier for the power.

It is basically a resistor string attached to the range switch. A 6AL5 type rectifier to turn measured AC into DC. The actual measuring circuit is two triodes forming a differential pair. The meter goes across the anodes, if I recall correctly. To measure resistance a 1.5 volt C cell is placed across the 1.5 volt range through a resistor. The value of the resistor is the same as what the midpoint of that resistance range show.

So basically any VTVM schematic will get you started.

You of course will need a multimeter of some type to get started. First you check the input voltage divider string to be sure all the resistors are good. The total value of the string should be 10 megohms.

Just for normal age I would replace the power supply capacitor. It most likely is a can type containing two or three sections. To keep the look the same, carefully pry open the bottom of the can and throw out the mess in there. Then you can fit in modern electrolytic capacitors to give you the values stamped on the can.

Of course you will want to test the tubes. If possible replace the two (or dual) triodes with ones that have close to the same gain. There will of course be a balance variable resistor control and be sure to clean the sliding contact and then use a separate drop of control lubricant. Do not try an all in one spray.

There really isn’t much in the way of circuitry inside. Lots of parts to give you ranges, but simple circuits.

Here is a typical schematic, your will be almost the same.

vtvm article

https://lazyelectrons.wordpress.com...vtvm-vacuum-tube-volt-meter-repair-n-restore/
 
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My VTVMs use more modern tubes and a solid state rectifier for the power.

It is basically a resistor string attached to the range switch. A 6AL5 type rectifier to turn measured AC into DC. The actual measuring circuit is two triodes forming a differential pair. The meter goes across the anodes, if I recall correctly. To measure resistance a 1.5 volt C cell is placed across the 1.5 volt range through a resistor. The value of the resistor is the same as what the midpoint of that resistance range show.

So basically any VTVM schematic will get you started.

You of course will need a multimeter of some type to get started. First you check the input voltage divider string to be sure all the resistors are good. The total value of the string should be 10 megohms.

Just for normal age I would replace the power supply capacitor. It most likely is a can type containing two or three sections. To keep the look the same, carefully pry open the bottom of the can and throw out the mess in there. Then you can fit in modern electrolytic capacitors to give you the values stamped on the can.

Of course you will want to test the tubes. If possible replace the two (or dual) triodes with ones that have close to the same gain. There will of course be a balance variable resistor control and be sure to clean the sliding contact and then use a separate drop of control lubricant. Do not try an all in one spray.

There really isn’t much in the way of circuitry inside. Lots of parts to give you ranges, but simple circuits.

Here is a typical schematic, your will be almost the same.

vtvm article

https://lazyelectrons.wordpress.com...vtvm-vacuum-tube-volt-meter-repair-n-restore/
I've downloaded about 60 meg of meter schematics none of which are even close to the Feiler unit.
 
Have you look at this one EICO 221 which was sold as kit too at that time (1950s)?
I have a EICO 221 which is in the rebuild process because it was put together by someone who couldn't follow the wiring diagram. Its not even remotely similar to the Feiler.

I am in the process of trying to draw the schematic in my limited free time. Being this was also a kit unit a factory schematic along with the calibration information would make my life easier.
 
I have a EICO 221 which is in the rebuild process because it was put together by someone who couldn't follow the wiring diagram. Its not even remotely similar to the Feiler.

I am in the process of trying to draw the schematic in my limited free time. Being this was also a kit unit a factory schematic along with the calibration information would make my life easier.
Eico 221 Schematic & Book here-

https://nvhrbiblio.nl/schema/Eico_221.pdf
 
Updated and finished schematic. I thought I was done when I posted the above schematic but in looking I had forgotten a few things. The schematic I am posting is of the working unit. It is surprising how good it works when its wired correctly and missing resistors are once again put into the circuit.
 

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