WE Rd. button Trimline w polarity circuit & dial light powered by line

[RotoTech99]

Dear Forum:

I have a WE round button Trimline (2220B handset & AD1? Base) with a rather unique feature...  in the handset modular adaptor it has a red disk(a capacitor maybe)  that is powering the dial light (photo attached) ; I don't know if it was a telco added feature or  what.

The handset dates from May of 1975, the base I'm not sure on... it is outfitted for modular cords,  though.

On the light shield,  there is a tag labelled
84 IL 2 The little red disk says Q8Z1 and GER2; it's providing power to the dial light bulb,  I can't tell where it's connected in the handset modular adaptor.

it's powered by the phone line,  but I learned quickly not to hook it to a dial light transformer equipped outlet.

I was hoping someone could please give me some feedback and advice on this odd,  yet functional WE Trimline.

the polarity guard is a little rusty because the phone was in storage, but got rained on a bit.

I let it dry out before I tested it,  so far it acts like it's new.

I was hoping please someone could give me some feedback and information on it; it's a pretty unique phone setup to me,  and anything I can find out will be helpful.

Thank you,  RotoTech99

[Key2871]

Well I've never seen anything like that before. But the letter Q is indicative of a transistor, and that along with a led replacement for the lamp would indicate that it was changed at some point. But I have not seen any leds in those only lamps. But lamps always burned hot, discoloring plastics and making the area around the light brittle over time.
So this must have been a retro repair some where along the line. But it most likely was done after the break up. Maybe by an outside refuber.
I've also never know a 2220B1 with a polarity guard, so that was most likely added at the same time as the light change.

[HarrySmith]

Got any pictures of inside the base?

[RotoTech99]

Dear Harry,

Here are the photos you asked for,  a top view,  and a bottom view of the base.

The bulb is incandescent,  not LED; that's why it mystifies me that that "red disc" is powering the dial light.  I wish I knew which it was.

RotoTech99

[Key2871]

Well that is odd. Although I looked close at the light and couldn't tell if it was led, it really didn't look like one..
But someone modified it so no separate transformer is needed. Ingenious but if it's not an led retro fit it is kind of pointless. But then again those were polarity sensitive so adding the polarity guard makes sense. It must have been modded before led "bulbs" we're available(?).

[RotoTech99]

Personally,  I think it was an idea in a service center as a short term fix of some kind.  I still think it's a clever way to use what's on hand.

I'm still kind of curious about the "84 IL 2" stamped on the tag on the light shield in the handset; I'm wondering if was denoting the line powered dial light?

If I had to guess, I think the 84 referred to a set modified or serviced around or just before the Bell System Breakup.

RotoTech99

[poplar1]

Please add a photo with the dial lamp "on."

[RotoTech99]

Dear Poplar1

:Here are 2 photos, one showing the dial lit,  and one showing the jack where it's plugged in at.

As I noted in my earlier posts,  there is no dial light transformer associated with the jacks in my house.

As to the base,  I was assuming it was an AD1,  The stamp on the bottom looks like it might say AD2,  it's too distorted to read clearly.

BTW: The duplex jack visible is to a 2012 dial light transformer I use for a test rig; it's not part of the house's phone jack wiring. The black line cord is from my Trimline.

RotoTech99

[RB]

That red thing may be a very-istor???
It would have been to limit the current supplied to the lamp.

[HarrySmith]

All good guesses so far. I have nothing to add. Is it possible to disconnect the Blue Thingy and see what happens? That would at least tell us what it does.

[Key2871]

The size indicated to me it was a varistor, but you said it said Q on it. After looking at it closer it doesn't say Q, simply O.
AD2 was a standard modular base for trimlines so that correct, I never worked with varistors so I'm not sure how they work.

[RB]

They work on current.
When power is applied, they have, I believe, a low resistance,
but as the current flows, it heats it up, and the resistance goes up, limiting the amount allowed to hit the bulb.
I think that's right

[Key2871]

Yes that sounds right, I remember something about temperature and resistance, hence varistor.
I'm surprised that it doesn't effect the line in any way.
I have a Harris Butt set with the amplifier that ran on the coin cell to power the amp, had it modified to do away with the coin cell and the guy added a transistor to power the amp from the CO line. It works perfectly.