110 Volts Power Supply

[Chris Suslowicz]

Originally Posted by Bob Carriere

Meanwhile check my pictures of the Variac I repaired.

Of course now I have question about the Variac.

Using a voltmeter I have confirmed that the numbers on the Variac dial are + or - 1 or 2 volts.
At 30 volts on the Variac dial I get 31.5 volts and the light is orange dim. 70 volts brighter

The strange thing is that it inputs 120.4 on the INPUT line but can actually put out a max of 137.5 volts ....... which made the lamp very very bright.

So I have concluded that the Variac is not only an adjustable voltage control but also capable of multiplying what is actually coming out.
Bob C

Yes, a variac is actually a variable transformer and can step the voltage up (slightly) as well as down. This can be useful if your AC supply voltage normally runs a little on the low side.

[Bob Carriere]

Thanks Chris

So the Variacs are variable transformers.....will be carefull not to over dial the output.

Else where on MLU it was recommended to slowly warm up the 110v PS......
How low should I start the voltage?
Are there any danger of causing a "brown out" at too low a voltage?
How long should I take to gradually ease up to 110Volts.?

Will I need to actually have a load on the PS to properly warm it up...?

I will heed you "CAUTIONARY NOTE".

I have carefully opened up the PS box.... I have observed 4 valves/tubes at the back end....... are they all rectifier tube of the same 6X5 number?
I did not remove them...... I remember my dad using a large non conducting fiber devide to slowly pry old valves from circa 1925 radio so as not to unglue the glass tube from the base.... is this a good practice on the WS 19?

Are there any practical way to testing the rectifier tubes to prevent toasting everything or is it a crap game....?

I did notice that the wiring of the huge transformer cans had empty provision for changing to 50 cycle....fortunetaly will not have to tamper with that.

I undertand the pin arrangement for the 12 volt cable to the power supply and will carefully check with a continuity tester to verify the polarity of the cable that connects to the CPP-2 power supply as the C connectors of the cable to the PS 6 pin are not clear indicated..... do not mean to find out what happens if you reverse the input polarity.

However, I am still not clear why the 110volts has the 6 pin connector out put and why it would go to the control box when being used as a ground training base....?

Be patient with my hard head.

Bob C.

[Bob Carriere]

On previous emails to Peter S..... on this side of the pond....

you wrote:

This is for the #2 power supply.......for a Canadian Mark III .........PS are they all the same?????

pin1 -12v heaters, -12v dynamotor & gnd
pin2 i/c speech
pin3 +12v heaters & relay
pin4 +12v vibrator & dynamotor
pin5 signal
pin6 -12v vibrator

If working only from the vibrator it is advisable not to power the i/c, A set & B set all at once as it loads the psu. Besides, there's nothing like the scream of a well lubed dynamotor.

Had to delete part of my message previous as it did not make any sense.

What I am trying to do with the above information is verify/confirm that the 12 volts cables from the CPP-2 PS are of the correct polarity because the ends that connect to the CPP-2 PS are not clearly indicated. I will use a simple continuity tester to check out pin numbers and clearly mark my cables for future reference


Again many thanks.

Bob C.

[Bob Carriere]

Went through the earlier posting on the Wireless forum and found a lot of information that answers all my questions...... now that I have my hands in to the sets the answers make a lot more sense.

Creating the wireless forum was definitely a good suggestion.

I will proceed with caution and try not to send smoke signals.

Need to find someone in the area for tube testing..... especially the 110v PS rectifier tubes.........

Thanks everyone.

Bob C

[Bruce MacMillan]

Bob, it sounds like you have things in hand.

I wouldn't worry about the 6 pin connector on the psu. There isn't much reference to it's use other than the audio/signalling pins. The pins that have the +12v from the regular battery cable are not connected internally.

Perhaps when the AC psu was developed they thought there was a need to buzz the operator, maybe as part of an intercom system ( or to notify of a brew up).

As to the variac, I use it to avoid the instant on inrush current to the transformer. More important is to keep the ac voltage at 110v max which is a lot lower than most line voltages. It only takes 5-10 seconds to dial the correct voltage. No reason to wait any longer.

Yes, get the tubes tested before applying power. As Chris said if one shorts it can turn a rare psu into a cheap boat anchor.

[Bob Carriere]

So I scored a Hickok TV-7 fully operational and calibrated tube tester.

Now I can't wait for it to get here.

Bob C

[Bruce MacMillan]

Excellent, that' a good tester. I have a "C" version that was made in Canada by Stark. There is very little difference between the various models, A,B,C & D except the "C" model comes with an adapter assy for English valves.

If you haven't already done it you should use the schematic & an ohmmeter to check the continuity of the windings. If one is open there's no use in proceeding further.