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IBM IBM/ITR Master Clock type 13-7 circa 1931

gerry_b

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Apr 28, 2008
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Hi,

I just acquired one of these beasts, rather beaten up, battle scarred, with a few minor modifications, but seemingly working, (and VERY loud between x:x:51 and x:x:54) ;-) My cat therefore hates it!

I have not yet checked outputs for bells and clock drivers, but currently have the bell outputs turned off.

I have spotted two modifications, one being a toggle switch that I think bypasses the lever switch labelled "Run" and "Advance" if that normally would advance the Program Dials once per second.., the other is a piece of old antenna wire connecting the transformer to the clock, both I would like to clean up.... OK, and I think the power cord came from a vacuum cleaner ;-) EDIT: The replacement cord came from an IBM Selectric Typewriter!

Anyway, I am wondering if anyone has the Service Manual for this, as I would like to give it a careful once over, while I am cleaning it up. I want to try to restore it to as close to Factory as I can, but I think I am lucky so far in that it runs after a 1500 mile trip to get here.

As I have never done this before, any advice/guidance/service manual pages are appreciated.

EDIT: Fixed link to Flikr Photos

The *dirrrty* pics are here

Yes, I have the Pendulum guide and serial number plate, they were just removed to start the clean-up :)

The Invar rod has a minor bend :-(

Thanks in advance!

Gerry

 

eskmill

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I don't think the transformer and copper oxide rectifier are original to your master clock although they appear to be the type IBM supplied for their AC powered master clocks.

The fuse holders on top of the case is strongly suggestive that your model 13-7 was DC powered from an external DC supply.

Too, the messy tar dripping on the relay board suggests that a transformer met its end-of-life inside the clock. :eek:

There's probably some significant alterations to the original wiring thus you may be forced to create your own wirning diagram or modify one intended for a similar model.

Use a test lamp and battery for point-to-point circuit tracing. An ohmmeter can be used but can be misleading for the kind of circuit tracing ahead of you. (i)
 

ibm clock

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Sep 5, 2005
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I am of the opinion that the 4 "fuses" on the left side behind the dial are resistors.

Looking at the rest of the pictures, it is a early clock. It has the duration timer. We talked about this timer in a past thread.


 

gerry_b

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Apr 28, 2008
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Eckmill,

Thanks for the information.

I finally pulled the dial to see what evil lurked behind.

I posted more pictures to the link above showing the burned area where the old transformer died as well as movement details.

I also found a toggle switch that I assume took the place of the original lever switch (Advance/Run).

If anyone has an "Original" transformer and can guide me on how to reverse the modifications, I would appreciate any input!

The wiring on the back of the clock appears to be unmodified, so I think most if the changes happened in the area around the transformer.

(But then again, you members of the NAWCC are the experts!) :)

Thanks again!

G
 

ibm clock

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Sep 5, 2005
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Toggle appears to cut the 2 second contact in and out of the circuit. On, and the clock will have hourly correction and will advance when switch thrown to advance. Off, no hourly correction, just once a minute slave clock advance, and no response to the advance switch in advance.

I don't think that transformer, though old, is original. It could be original, if there are no extra holes on the black base.
 

gerry_b

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Apr 28, 2008
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IBM CLock:

Thanks for the information

The toggle seems to advance the program disks one minute per clock second.

I have not experimented with the "Advance/Run" lever switch. (yet)

The transformer has two mounting holes, only one of which will align with any of the holes where the original transformer was mounted. The transformer is just hanging by one screw currently.

There are burn marks in the case where Ekmill pointed out, the original transformer gave up its life.
 

ibm clock

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Sep 5, 2005
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Non original transformer. Bring up a point though. On slightly later clocks there are multiple taps. For example, my IBM model 25 ca 1949 has 24v tap for the relay coils as well as clock contacts, 40v tap that supplies ac only to the rectifer, and thus I measure 36v out at the slave clock terminals, and a 60v tap. On the top pf the clock are posts for 24v and 60v. Pesumably these are for bells and other devices. Now, I'll bet your transformer only has one output voltage, hence som creative modification.

I would assume this early clock would also have had a multi tap transformer, but could be wrong as my experience with thise clocks is limited to my 1949 IBM master and a late 1950's Simplex master(essentially the same circuit as my IBM.)

Sounds like the toggle is taking the place of the advance swith. I thought maybe is was a way to take the two second contact out of circuit to disable the correction cycle.

BTW. Do you have any prior expereince with IBm clocks or other master cloks?
 

harold bain

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Gerry, I wouldn't worry about the transformer, it was likely professionally replaced by IBM or Simplex. Just make sure it is secured properly. The run/advance switch is just for rapid advancement of the slave clocks. The middle position is to shut them off, as for fall time change. I'm pretty sure those are fuses, on the bell circuits. How does the movement look, for wear/dirt?
 

eskmill

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I am wrong. I said, "The fuse holders on top of the case is strongly suggestive that your model 13-7 was DC powered from an external DC supply."

What I failed to see is the porcelain fuse block on the top of the clock and the porcelain bushings used for the 110 VAC circuit to the transformer. :bang:

I believe the reason for the multi-tapped transformer used in the older IBM master clocks was to allow compensation for aging of the rectifier. The copper-oxide rectifier seen in Gerry's flicker photos is noted for two characteristics; one, their ruggedness, long life and ability to withstand overloading. The second characteristic is their inefficiency and large voltage drop thus they need 42 volts AC to produce the 24 volts DC required to advance the bell timer, clocks and maintain the movement mainspring.

The same transformer was used by IBM when the copper oxide rectifier was superceded by the more efficient selenium rectifier that needed only about 29 volts AC to provide 24 volts DC. The selenium rectifiers "age" and often need an input voltage increase as they age.

The up-to-date silicon rectifiers are highly efficient, have low voltage drop and if used as a direct replacement for either the copper oxide or selenium rectifiers produce a higher DC output voltage and make the clock very noisy.
 

eskmill

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I obviously clicked reply twice. Subsequently, I looked through my supply of old IBM parts and found a transformer. Its made for either 120 or 240 volt AC inputs and can supply 110 watts continuously or 150 watts intermittently. The secondary has four wires: common, 24, 36 and 42 volts.

This transformer is somewhat smaller physically than what I recall in the model 25's and was probably used in the IBM master clocks made by Simplex after 1958 in the US.





 

ibm clock

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Yes, a perfect replacement transformer could come a later Simplex master clock.

Should verify the coil voltage. Most likely they are 24, but we have seen other voltages used.

I mention the multiple taps, to clue you in on the reason allthose wires are there for the transformer.

Of course, you don't need a multitap transfore,r if all the coils are the same voltage , just one at rated voltage, and enough output.

Here is the power supply from my clock. On top of the transformer are the AAC input wires. To the right side of the transformer are where the transformer primary wires attach. Top to bottom next left side of trasnformer are Common. 24V 40V 56V. The rest are the terminals to the clock. A B C 1 2 3 4 5 6 7 AB PC. 7 is the 24v feed. There is also a wire that goes to the top of the case to a terminal. 24. v for external devices. Also others may note the duplex relay and the master relay at the bottom.

Of course, you clock will be slightly different.
In one of the recent IBM model 25 threads there is a general power supply diagram posted. Enough to use as a guide. Also in the other threads on these clocks was a post discussig the duration timer.


 

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gerry_b

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IBM Clock: No, this is my first IBM/ITR master and I want to be careful with it!

Harold: The transformer needs to be remounted, as it is dangling by one screw against the rectifier.

Eckmill: I see at least two non-connected taps on the transformer, but I have not yet seen what the outputs are. The transformer that is in the clock looks like it may be 1/2 the size of the original, based on the mounting screw locations.

IBM Clock: thanks for the picture and explanation, I will look for the other thread about power supplies.

I have corrected the flickr photo group to contain the new pictures without the face.

I started cleaning the top of the clock, and it appears that there may have been two AC inputs as the fuse holder on the side that does not have the power cord is also labelled AC.

I am going to work on diagramming the top and back wiring first, then move inside.

I will keep you informed as I go!

Thanks Guys!
 

harold bain

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Gerry, unless you are going to run a large system of slaves (25 or more), I wouldn't worry too much about the size of your transformer. It should do the job just fine, as long as it puts out 24 volts DC. The second AC input could have been for bells.
 

ibm clock

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I've been looking at your pics of the transformer. I sees like it may be a newer IBm transformer. I see it is mulittapped, so measure the output. IF you have a common, 24v. 40v, and a 50v tap is is a IBM. The soldered on eyelets are a clue. There may be wire tags on the leads with nubers. Should have +- 24v 40V 50V.

also, I think transformer should be turned 180 degress, then might line up better with terminals. Do you know what that relay on top of the transformer does?

I took my power supply board off, and basically traced the wires out to make a point to point wire diagram. Someday, I'll convert it to a schematic.
 

gerry_b

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Nice thought on rotating the transformer, unfortunately it only has two mounting holes oriented diagonally, so only one will match up with the case holes.

I keep hoping that someone here may uncover the schematics, diagrams, and/or manuals for the model 13 ;-)
 

gerry_b

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The original transformer was either huge, or mounted on a "daughter board" as the mounting screws are in a 6" x 2" rectangle.
 

harold bain

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Interesting patent, Gerry. The program was originally meant to be driven similar to a timeclock recorder movement.
6 x 2 sounds about right for the original transformer. They were also used for slave clocks, so were made heavy duty.
You could get by with a much smaller transformer if you aren't going to power a school full of clocks.
 

gerry_b

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I have a general question about "reversing" the modifications in this clock:

Is it better to use wires that are the original color, and "Hide" the fact that it is not an original wire, or use another color, and indicate that some modification was made? I mean, someone used a piece of old twinax TV antenna wire to hook the replacement transformer in... I have to replace that with something :)

This company sells cloth covered wire in a variety of colors, and I was thinking that since all of the wire in the clock is black, that Brown might be an indicator of the fact that it is a "new" wire, rather than the original.. or Yellow would point it out unconditionally ;-)

http://www.radiodaze.com/wire-cloth_covered.htm

The real question is, when returning a clock to "As close to authentic as you can get" Do you try to completely hide the fixes, or make them slightly noticeable, to indicate that a minor change exists?

Thanks.

G
 

harold bain

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Gerry, I wouldn't worry too much about the wire, as long as you are using a reasonable sized replacement. I wouldn't use a colored wire that stands out as being a replacement, though. You could document the restorations you have done, and put them in an envelope attached to the back of the clock.
 

fdew

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Jul 12, 2007
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I agree with others that your transformer and are safe enough, but if you want to remove the transformer to make things look nicer, I would find a steel box and put that transformer in it, While you are at it get a 10 amp or so bridge rectifier (10 amp just because they are cheep and easy to mount, Pick up a couple of in line fuse holders and put one on the AC input to the transformer. Use about a 1 or 1.5 amp fuse. Put another fuse on the DC out. This one could be 4 or 5 amp. Then run the 24 volt DC to your clock Connect it where the DC output of your existing rectifier connects now. and disconnect at least one wire from the old rectifier. Now there is only current limited low voltage DC inside your clock.

BTW Fun fact. Those old rectifiers would make a little hum when the had a load on them. When I was setting clocks I would send pulses on just the A and C wires, and listen for the rectifier hum. When there was no hum I knew all the clocks had made it to the 59th min Then I would throw the advance switch to move them to about 10 after, then just on A and C again.

If you just threw the Advance switch to move more then just a few hours, some of the sluggish slaves could get over a hour behind, then you had to go around and find them and set them by hand
 
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