1958 Mahogany Brown 564 Key Set

[TelePlay]

All I need now is some "aged" paper to match the light brown of my vintage dial card, but it looks very nice with some satin photo paper used to print.

A hot iron applied to non-bright white or off white card stock can "toast" paper to whatever shade of "old" you want.

[Dave F]

Nice phone!  Yes, mahogany is a great color.  Too bad they didn't continue producing it.  Here's a picture of my mahogany 544 4-button keyset:

http://www.classicrotaryphones.com/forum/index.php?topic=3261.msg43316#msg43316

DF

What is the manufacturing year of your 544?

3/56

DF

[poplar1]

Although I'm sure many will disagree, sets like this one do have some historical value as presented---even if the phone company bean counters don't see fit do allow Pioneers to keep their museums open. While there is no way to hold the outside line, still, having the lights "work" is clever.

As wired, with a 3-pair mounting cord and transformer, it can be used as a working 2-line phone* without a key system. Perhaps it was intended to be connected to one line (or simulated line) and intercom (last key).

EDIT: * WITH RINGER ON 1ST LINE ONLY

I'm thinking about copying this wiring in a junker 564 or 2564 that already has the mounting cord cut off. Don't panic; no matching date complete phones or WE brown sets will be harmed in this process.

[poplar1]

It was common within the Bell System for phones that were to be on display to be butchered so they were non-functional.  Some were displayed in lobbies or in the Business Offices.  Others were loaned by the PR department for use at trade shows, props in productions and color-coordinated displays with fashions and home furnishings at local stores, etc.

There was some discussion a while ago about several display sets with F- codes that were auctioned on ebay.  Most were "gutless" -- having been built with no networks or other internal components.  For display purposes, the Bell System wanted the phone to look normal, but be useless if it "walked off" while it was on loan.

We are fortunate that our sets from the Cleveland auction only had the mounting cords missing!

Amen!  I actually won some items at that auction too...   One was a set of three 302-type telephones, which I thought looked in decent shape if one looked underneath the dust.  Well, they were, the shells are in great shape, but they turned out to be display decoys, completely empty, and the bases were very nicely made wooden plates with proper leather feet attached.  Even the hook switch assembly was massacred, having only one spring to make the plungers work nicely. Dials were nice and complete, sans wires, and handsets were in nice shape too. Not what I expected, but the parts aren't bad.

I think they probably felt that cutting an expensive 30-conductor cord was too much a waste, so they removed it nicely, or were these cords ever installed at the factory? It seems it would make sense to install them based on the customer configuration requirements.

I believe Lec. Dem. stands for Lecture Demonstration.

I knew that there had to be a better explanation!

Thank you!

Desk keysets were equipped with mounting cords before leaving the factory. While the 400-series keysets had many different configurations, which required different conductor counts for different models, the 500-series keysets were moving toward standardization. For example, several keys (buttons) could now be converted from Pickup (line appearance) to Signal (momentary action) rather than having to order different sets.

You could provide the most common features with either a 564 or 565 keyset. The 564 set had a 30- or 34- conductor mtg. cord (depending on the year of manufacture), while the 565 set had a 50-conductor mounting cord. Some of the additional conductors in the 565 were needed for external speakerphone or for excluding other stations.

[unbeldi]

Thanks Unbeldi for the Excel file!!  I needed to tweak the size a bit for my printer, but it works great, and I can my own numbers/extensions to the other lines.  All I need now is some "aged" paper to match the light brown of my vintage dial card, but it looks very nice with some satin photo paper used to print.

Also I appreciate the wiring detail to make the lights work.  Is this the same 6-8v princess transformer??

Glad the designation strip template worked for you.

The KSU power for the lamps was nominal 10V AC, but you can use almost any power cube up to that voltage from 7-10 V AC or DC.  I had a 7.5 V regulated DC power cube lying around and wired it into one pair of my 6-conductor mounting cord. 7.5 V doesn't light the lamps in full brightness, but it's adequate for the demonstration effect of having the key light up.

The 2012A transformer for the Princesses actually outputs 14.5 V without load which drops down to the 8V nominal voltage when the Princess lamp is connected.  The KTU lamps have a much higher resistance than the Princess lamps, and the voltage only drops to approx. 13 V, so the lamp is running actually too high, but I don't know what the acceptable range is without reducing the life time of the lamps. I just chose to use another supply and save a 2012A for its authentic use.  My way of lighting these lamps is not authentic anyhow.

[unbeldi]

Although I'm sure many will disagree, sets like this one do have some historical value as presented---even if the phone company bean counters don't see fit do allow Pioneers to keep their museums open. While there is no way to hold the outside line, still, having the lights "work" is clever.

I agree that it is 'nice' to be able to demonstrate a very visible feature of these set, the lit keys, without having to have a complete key system.

In the mid 90s I restored an old 1A2 system with a pile of old phones, that I found in the unfinished back space of an office floor I rented, without having any documents or wiring diagrams, to fully working state and I thought it was cool to have an old system like that working with lit keys and all.

As wired, with a 3-pair mounting cord and transformer, it can be used as a working 2-line phone without a key system. Perhaps it was intended to be connected to one line (or simulated line) and intercom (last key).

On this set I wired the two lines into a 2-line modular jack, so with a standard 2-pair modular cord, both lines are available. In my case, this cord would likely be plugged into a Cisco call router with dual FXS ports, which have both lines on the first port, or into a channel bank. Behind the Cisco router I can route the function of each line anyway I wish, to the PSTN, to C*Net, or to my Kellogg switchboard if I choose.

I'm thinking about copying this wiring in a junker 564 or 2564 that already has the mounting cord cut off. Don't panic; no matching date complete phones or WE brown sets will be harmed in this process.

Exactly, this is all easily reversed, everything in the telephone set has screw terminals.

[unbeldi]

Addendum to the power supply question:

The correct transformer to use for the key sets is the type 393B which supplies 9-11 V (nominal) at up to 2.8 A, to power up to 72 #51A bulbs, acc. to the BSP.

A good BSP reference for the transformers for these early sets is 501-136-100, Issue 3 (June 1968), entitled "Station Transformers - Identification". There were several versions of this BSP after this, but they may not all describe the 393B anymore. The 2012-series transformers are discussed.

The 393B transformer is probably rather difficult to find these days, but also rather unnecessary for lighting a single bulb.

[poplar1]

Thanks Unbeldi for the Excel file!!  I needed to tweak the size a bit for my printer, but it works great, and I can my own numbers/extensions to the other lines.  All I need now is some "aged" paper to match the light brown of my vintage dial card, but it looks very nice with some satin photo paper used to print.

Also I appreciate the wiring detail to make the lights work.  Is this the same 6-8v princess transformer??

Glad the designation strip template worked for you.

The KSU power for the lamps was nominal 10V AC, but you can use almost any power cube up to that voltage from 7-10 V AC or DC.  I had a 7.5 V regulated DC power cube lying around and wired it into one pair of my 6-conductor mounting cord. 7.5 V doesn't light the lamps in full brightness, but it's adequate for the demonstration effect of having the key light up.

The 2012A transformer for the Princesses actually outputs 14.5 V without load which drops down to the 8V nominal voltage when the Princess lamp is connected.  The KTU lamps have a much higher resistance than the Princess lamps, and the voltage only drops to approx. 13 V, so the lamp is running actually too high, but I don't know what the acceptable range is without reducing the life time of the lamps. I just chose to use another supply and save a 2012A for its authentic use.  My way of lighting these lamps is not authentic anyhow.

I remember a high school teacher saying that if you left the dash lights in your car adjusted to only half, they'd last forever. So connecting lamps rated at 10 Volts AC to a lower voltage is good; the tradeoff is a dimmer lamp.

There are usually lots of "orphan" power supplies at thrift stores, from answering machines, cordless phones, etc. I thought it would be safe to use one of these so long as it was rated below 10 VAC (or about 8 VDC?) for a 51A lamp found in multi-line sets. Or one rated below 8 VAC (or 6 VDC?) for a Princess or old Trimline lamp.

In the example you stated (2012A). 8 Volts was measured under load of one Princess lamp. But is the type load always known by a manufacturer when rating a transformer? If not, how can they determine what value to list?

[unbeldi]

I remember a high school teacher saying that if you left the dash lights in your car adjusted to only half, they'd last forever. So connecting lamps rated at 10 Volts AC to a lower voltage is good; the tradeoff is a dimmer lamp.

There are usually lots of "orphan" power supplies at thrift stores, from answering machines, cordless phones, etc. I thought it would be safe to use one of these so long as it was rated below 10 VAC (or about 8 VDC?) for a 51A lamp found in multi-line sets. Or one rated below 8 VAC (or 6 VDC?) for a Princess or old Trimline lamp.

Well, I think almost every manufacturer specifies that the power supplies for their equipment should only be replaced with an original manufacturer's unit. There is a reason for that, because many supplies aren't specified fully on the label. You have to consult the data sheets.

The voltage alone is not sufficient to specify a power supply or a transformer cube. The other information for full compatibility includes rated power (in volt-amps VA), which is almost always provided, but also impedance. Impedance directly relates to the no-load factor, max short-circuit current, and whether the supply is short protected by design. Power supply selection also includes the impedance/resistance of the equipment to be powered, similar to impedance matching in audio transformers.

In the example you stated (2012A). 8 Volts was measured under load of one Princess lamp. But is the type load always known by a manufacturer when rating a transformer? If not, how can they determine what value to list?

The 2012A transformers are designed for one specific application, to provide power to ONE lamp in the dial-illuminated sets: Princess, Trimline, and the Mushroom-lamp-500s. The BSPs state explicitly (READ-->)  what must be used or cannot be used.

In the case of the 2012A, the primary winding impedance is around 750 Ω, secondary is about 15 or 16. This is relatively high and would provides a substantial no-load voltage above rating. the Princess lamp has a cold resistance of about 3 Ω and 27 Ω hot during operation.

The specified max. load of the 2012A is 1.75 VA, so at the specified output 6-8V, say 7 V, the max operating current is 0.25 A.  This is exactly the required current of the Princess lamp when running at 6.7V.

I found that when the 2012A transformer is short-circuited on the output, this current level is reached at an input of around 56 V. This means its impedance is right around 50% (56V / 115V) and therefore the max short-circuit current is 2 x 0.25A = 0.5 A. This is how transformer impedance is usually measured, in %, and also indicates how much the output voltage drops on full load.

I read somewhere that some early 2012A transformers sometimes burned up, but I don't know if this is the reason for making the 2012C, and I haven't got to possessing one to test it.

[unbeldi]

In the example you stated (2012A). 8 Volts was measured under load of one Princess lamp. But is the type load always known by a manufacturer when rating a transformer? If not, how can they determine what value to list?

So, in short, for AC power supplies the output voltage is specified, I believe always, when the transformer is loaded to the specified power rating (VA). Perhaps this applies to unregulated DC supplies as well. If the equipment powered doesn't fully load the supply then one needs to worry about over-voltage.

For regulated DC supplies we don't have to worry about high voltage, just look for sufficient current output.

[poplar1]

Thanks for the info. It now appears that finding an acceptable replacement transformer just got more difficult!

I believe it's only the Princess transformers manufactured by Ault that were at risk of causing fires.

It is permissible to have only one Princess lamp per 2012A or 2012C transformer. However, because the Trimline doesn't have a night light, it is allowed to have more than one TML connected to the same 2012A or 2012C.

[unbeldi]

Thanks for the info. It now appears that finding an acceptable replacement transformer just got more difficult!

Not much, though.  In any case, you don't want to expose a 50 year old key set lamp to some little understood power supply. These lamps aren't exactly plentiful and I am content running them at a little lower voltage.

It is permissible to have only one Princess lamp per 2012A or 2012C transformer. However, because the Trimline doesn't have a night light, it is allowed to have more than one TML connected to the same 2012A or 2012C.

I don't understand that argument, what has the night light feature to do with it?
I do understand the argument that a lit night light draws current while another extension might get picked up, thereby exceeding the 2012A current limit, that's why they specified only ONE Princess per transformer.

On the Princesses, the switch connects the transformer to the lamp via a resistor in series, which is shorted by the hookswitch, to light the lamp fully when off-hook.
The lack of the night light shouldn't impact the current draw of the Trimline lights when the unit is off-hook. So, the argument seems to be that the Trimlines somehow draw so little current that it doesn't matter.

I have seen the note in the later BSPs that "any number of Trimline sets ..." may be connected to a 2012A or C along with one Princess, but I don't understand that. Surely not "ANY" number. This seems to refer only to the later Trimlines that use LEDs for lighting. An LED at that time may have drawn at least 20mA, so at least a dozen sets seems realistic, more actually, since only a few families can pickup a dozen telephones simultaneously and they probably couldn't afford all those telephones.

The early Trimlines used #53A or B bulb, and it seems they could run even on 10V AC with a 101G power supply on KSUs (502-320-000 Issue 1).
I don't have one to test.

[poplar1]

It is permissible to have only one Princess lamp per 2012A or 2012C transformer. However, because the Trimline doesn't have a night light, it is allowed to have more than one TML connected to the same 2012A or 2012C.

I don't understand that argument, what has the night light feature to do with it?
I do understand the argument that a lit night light draws current while another extension might get picked up, thereby exceeding the 2012A current limit, that's why they specified only ONE Princess per transformer.

To clarify, I should have said any combination of Princess, 500s with dial lamps, and Trimlines, so long as the total of one night light is not exceeded. I'm still looking for documentation of this.

On the Princesses, the switch connects the transformer to the lamp via a resistor in series, which is shorted by the hookswitch, to light the lamp fully when off-hook.
The lack of the night light shouldn't impact the current draw of the Trimline lights when the unit is off-hook. So, the argument seems to be that the Trimlines somehow draw so little current that it doesn't matter.

The argument would be that an when a TML is on-hook, its lamp draws no current. Therefore, having other TMLs and 500Ps + one phone with night light (Princess, 500U) doesn't affect the brightness of the dial lamp on the one *Princess or 500U* that is in use. However, as you point out, if you were using a non-night light phone (TML) and the night light on the Princess was on, this could affect the total load on the 2012A. Whether this is considered an overload or how this would affect the brightness of the TML dial lamp needs to be determined

I have seen the note in the later BSPs that "any number of Trimline sets ..." may be connected to a 2012A or C along with one Princess, but I don't understand that. Surely not "ANY" number. This seems to refer only to the later Trimlines that use LEDs for lighting. An LED at that time may have drawn at least 20mA, so at least a dozen sets seems realistic, more actually, since only a few families can pickup a dozen telephones simultaneously and they probably couldn't afford all those telephones.

LED  TMLs don't use a transformer since the LED is line-powered; that's why it flashes on and off when dialing out on a rotary model. In fact, there are only 2 wires used of the 4-wire handset cord. There is no need for a transformer since the only time the dial is lit is when the phone is off-hook (i.e., there is no night light).

You may be thinking of the Signature Princess: the LED dial is line powered, but if you want the night light feature, then you must add a transformer.

The early Trimlines used #53A or B bulb, and it seems they could run even on 10V AC with a 101G power supply on KSUs (502-320-000 Issue 1).
I don't have one to test.

With a 10 Volt power supply, you would use 51A or 53A (10 Volt Lamps) instead of 51B or 53B (6.25 Volt lamps).

But you would also use a 51A or 53A with a 2012A if the combined length of the handset and line cord was over 15 feet, if dial lamp was not bright enough.

So 99% of the Trimlines you find probably have 51B or 53B lamps. The older hand sets were manufactured with 53B lamps and newer sets had the larger 51B lamps (in the horizontal position).

"Lamps carried for maintenance reasons should be of the 53B-type since both early and current production handsets accommodate this type."
(Iss. 1, 502-303-101, Feb. 1970, Paragraph  5.05)

[poplar1]

Here's part of the confusing details of multiple "dial lights" [TML] or "dial-night lights" [PRN] connected to one 2012A or 2012C transformer:

BSP Section 501-136-100
Station Transformers
Identification

Issue 5, May 1972 states:

            ...3.06 Only one dial light or night light may be connected to
            a 2012A  transformer.

However, Issue 6, November 1978 states:

            ...2.02 Any number of TRIMLINE telephone
            sets per residence along with one
            PRINCESS telephone set may be
            powered from one 2012A or 2012C
            transformer. However, only one
            PRINCESS telephone set can be
            connected to a 2012A or 2012C
            transformer. When installing
            multiple PRINCESS sets use
            KS-20426L3 transformer or provide
            an additional 2012A or 2012C
            transformer for each telephone set.

There are also restrictions on the number of lighted dials fed by the same inside wire. So that even if using a KS-16940 L1 transformer capable of supplying 30 "dial night-light telephone sets," don't use common feeder when "more than two sets may be off-hook at the same time." And if using a KS-16686 L2 transformer (up to 10 sets), don't use common feeder if "more than one set may be off-hook at the same time." (Issue 4, May 1969).

[unbeldi]

Here's part of the confusing details of multiple "dial lights" [TML] or "dial-night lights" [PRN] connected to one 2012A or 2012C transformer:

Yes.

The bottom line is NO ONE can connect "ANY NUMBER" of lights to these transformers, they just don't have enough power to do it all for all circumstances.

But the good news is that the 2012A transformer should be short-circuit safe.  Short-circuit current is 0.5 A on a 115 V line, and it shouldn't get overheated that way.

On my short circuit tests, I pulled as much as 400mA out of the 2012A, when the input was at 90V, and it didn't get noticeably warm, but I only sustained the condition for perhaps 15s.