atcomsystems.ca/forum Forums General General Telephone & Systems Information WEAK BELL IN OLD PHONE

ok, where is the cap/condensor physically located in the phone? am i missing something?

Inside the network "block" and brought out on "A" and "K". I think you are looking at the buzzer on that schematic that somebody linked but was removed. I remember a 50 ohm resistor and a cap.

By the way, .1uF wound not be an electrolytic.

-Hal

There's another capacitor on the schematic, labeled "condensor", although it lists no value.

Is it against the rules to post a schematic? Might save us all some time.

Otherwise, if anyone is interested, let me know and I'll PM it to ya.

...ok, im going to try to get a voltage reading off the ringer, then probably put external cap across a&k, and the slate and slate/red ringer leads. also gonna try the bias spring in the unhooked position. i would love to hear this thing go RIIIINNNNNNNG, instead of ding-ding! lol

bob

oh, i noticed too that on the bottom plate of the phone it says 510FM. hope this doesnt make a diff, i just figured as long as it was a mod 510 series, the FM wouldnt mean much...bob

No, it's not aginst the rules to post a schematic but SST already did. That's the "official" one I have right out of the Bell System Practices.

It doesn't matter what you have, every 500 and 2500 was the same as far as the ringer goes. Check the cap if you wish but I doubt it is a problem. By the way, disconnect the slate and slate/red and connect them to your test cap, don't just bridge it across A & K. Otherwise you will have .2uF. Not a bad thing but not right either.

-Hal

My apologies if this is already covered in the practices manual. Also if I'm stepping on anyones toes. I know this isn't my field, but if I can try to help, I don't see the harm, and maybe I'll learn something along the way.

- Matt

pg 1

pg 2

pg 3

Bob, the "F" is the revision of the 510 set. The "M" indicates that it is modular (cord or cords). Wiring is the same regardless of whether it is modular or not.

I looked @ the schematic of the 510 (Thanks Matt, but I already had gone there and printed it) and now I see where the .1uf came from. That's for the buzzer circuit. As Hal said, the capacitor of interest is between the 'A' and 'K' terminals, in the network.It is NOT an electrolytic capacitor. It is what is/was called an 'interstage coupling capacitor' in tube amps, radios and etc. They used to be as big or bigger than the average adult male's THUMB. Now with Mylar and plastic, instead of paper and copper or aluminum foil, they are reduced by 1/2 or better.
I will repeat the value, 0.47uf at 200-400 volts. You can confirm this by laying your mitts on a late ITT network,that is on a PCB. The components are labeled with standard EIA methods, no cryptic 'house' numbers. If there is nothing wrong with the exhisting cap, putting another in parallel with it may cause ring trip, as it will load the line with 100% more power demand. Recommend you take the leads that are on 'A' & 'K' off the network and hook them directly to the capacitor, for testing. Unless someone has been messing around with the network or otherwise fooling arond in the phone, I doubt the cap is the problem. I have seen 1 of the bell coils hooked up backwards cause your problem, but again, doubtful. Truth be known,your bias spring is probably 'tired'. John C.

...i moved the bias spring from the hooked postion to the other postion and the ringer rings somewhat louder, but not really up to snuff. i checked the voltage across tip&ring while phone is ringing,and as the phone starts to ring it is 105vac, and at the end of the ring cycle it is 120vac, seems to be plenty of juice. might be the bias spring like lightninghorse mentioned. i guess i will keep my eyes out for another old phone for parts!..bob

Bob, I'm sending you a private message.