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Help needed identifying this telephone.

Started by jonboysez, September 29, 2012, 07:45:01 PM

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jonboysez

If its the capacitor that is faulty its game over isn't it?

twocvbloke

Quote from: jonboysez on October 04, 2012, 05:16:27 PM
If its the capacitor that is faulty its game over isn't it?

Nope, that's why you can buy replacement capacitors to wire into stuff, cutting out the faulty one... :)

jonboysez

Is there anyway of testing it? - I did what you said and got zero resistance between L1 and L2 with plunger pushed down.

dsk

Just to be sure we talk the same:
When you say zero is that equal to open probee or shorted probes?
If it is equal to shorted probes we have to do something.

The good thing is that this capacitor is double, and it will work well redesigning it to use only one of them.

dsk

jonboysez

Look at reply no59 - not sure what you mean "open probe"? I am a novice with multimeter.

dsk


jonboysez

Well I put ohmeter to 200 ohms setting, attached red probe to L1 and black probe to L2 (with phone not plugged into wall socket, but all wired inside phone correctly) and got a reading of 40 ohms off hook and zero ohms when I pressed down on the metal strip that the plunger presses down on (on hook) - I'm I right in thinking "off hook" means when handset is picked up from phone prior to dialling number? (and "on-hook" means when receiver is replaced back on the phone)?

dsk

#67
That's right.

:-[ I have referred to wrong terminals on the dial.

Dogged this out, and measured.

In rest position
B-D contact (0.1 Ohms)
Rest no contact. (Meter displayed 0.L)

With paper as pictured: no contact. (Meter displayed 0.L)
I'm sorry!

dsk

jonboysez

Eh you've got nothing to be sorry about! You have already helped me more than I could expect! Its not a problem as I have other phones that I haven't been able to get working properly - these phones might be over 50 years old so it is a wonder that any are still working. I will probably relist them on a well known web site but not for a good while.............

dsk

Getting a stable measurement of the capacitor is not easy.
20 MegaOhms or more should be perfect.

dsk

jonboysez

Sorry I'm a bit confused now - am I puting probes on L1 and L2 and checking resistance on hook? Getting zero ohms . Which is the capacitor? - is it the black square thing with "Bell" written on it in my phone? What does O.L mean? I dont get that on my multimeter I don't think - is that zero or is it infinity?

dsk

#71
Yes that's the capacitor.
Th O.L comes when my meter are not able to measure any resistance. It is the same as if I just don't touch anything with the probes.

Zero ohms are equal to the reading when the probes touch each other.  Or the same as a short.

dsk

jonboysez

ah I get a "1" on the left of multimeter screen when probes not touching anything - so that means infinity (8 sideways) on my multimeter.