Relay Gapping

[Babybearjs]

thought I'd throw this one out at you all.... I have a vintage 1A1 key telephone system. this past week I revamped my system.... once back up and running I started to have issues with my "R" relay as they are now all "Fluttering" when a call comes through on any line. Prior to this problem, we hade the cable go down in our area that also effected cell phone use... (probably a downed power pole...) anyway, once we got the system back up and running that's when the relays started to fail.... my question is.... should I adjust the gapping on all the relays, or leave them alone. the 212KTU is dated from 1963 and works quite well... I have a brand new unit that I could use, but want to try to address this issue first..... (diagnostics: "r" relays vibrating instead of seizing. possibly from low voltage?)

[rdelius]

Temporally bridge a large capacitor across your dc supply .See if the problems go away

[Babybearjs]

when the DC is off, the problem goes away. who on this board is well versed in the 1A1 systems? I don't understand where the problem is. this was working fine and now this has cropped up... here is a list of connections based on the schematic from 518-114-110 and the 1A1 manual from 1955 (both from the TCI Library.)

210A KTU:          212A KTU:
#11 "W"  wired to #38B "FB" Relay Contact
#12 "S"   wired to #37B "FB" Relay Contact
#13 "F"    wired to #37A  "F" ("FA" contact on FB relay)
#14 "TO"  wired to #27A  "TO"
#15/16 "HA"  wired to #19B  "HA", also wired to 202B #37

please verify for me.... if you can... do I have something reversed, or redundant....  the FB contacts seemed weird... are they suppose to work like that? paperwork seems to be missing more details

[rdelius]

Try what I suggested. If a filter capacator in your dc supply gets leakly, relays might chatter because the voltage is not smoothing out.Your power supply might be 50 or more years old

[Babybearjs]

I switched out the P/S today, the old 101G got mounted next to the 20B2. I'll try what you suggested... if that's the problem does it indicate a bad cap? when I plugged it the 101G, the system came right up... so the cap is suspected... I'll have to take the specs on the cap to see if I can replace it with something newer. I have another 20B2 that had a bad rectifier... changed it out and the caps started to over heat and leak....pulled the unit until I can get it properly fixed... If Both caps are taken out, how will it effect the line?

[twocvbloke]

If the power going to the relays is intended to be DC (as you can get AC relays too), and the smoothing capacitor on an AC-DC rectifier circuit has failed, then it'll introduce a lot of unsmoothed rectified AC ripple, meaning things like relays will rattle as they're basically being pulsed on and off when they need to be kept powered up...

[Babybearjs]

Thank You for the clarification. that exactly what's happening. I pulled my 101G and have it running the system for now. if I short that cap, will it solve the problem, or make a new problem?

[twocvbloke]

If you short out the cap, you're just basically removing the smoothing, but if you add another cap in parallel with the bad one, you're creating new smoothing, which is what you want, but ultimately, you should remove the bad cap and fit a new one, just a quick bit of de-soldering most likely, just remember to get a capacitor of the same type (usually polarised electrolytic) and capacitance rating, you can go up in the voltage rating, but not down...

[Victor Laszlo]

Since the cap is in parallel with the D-C output, shorting it will fry your rectifier and release the magic smoke.

[Babybearjs]

OH No! don't want to do that again.... already wrecked 1 20B2 unit....lets not try for a second...  I wrote down the specs off of the large cap, it a KS-19846-L4 unit, and I'm not sure of the value... it has a value of 4600 and I'm not sure if the was a period at the beginning of the value or not... so I'm not sure if it is suppose to be .4600UF or 4600UF. (or is it PF??) anyway, if anyone knows the part number, please tell be what the value is suppose to really be.

[twocvbloke]

If you could get a clear picture of the capacitor, it might help us identify it (assuming someone else doesn't come along to say what it is!)...

Looking at some pictures of similar caps, going by the size of them, it's most likely 4600 Micro Farad, but it's best to see the numbers first...

[Babybearjs]

Thanks, I'll try to post a picture soon....

[Victor Laszlo]

Any value from 2,000 to 4,000 uF will work.  Be sure to get working voltage above 35Vdc or so, be sure to get  "ELECTROLYTIC" and be sure to install in parallel across the output. + to + and - to -.

[Victor Laszlo]

Is your KSU grounded?

[Babybearjs]

Yes, I made sure of that 2 weeks ago when I revamped my system. Finally put in a wooden backboard for everything and then moved everything over onto the new board. finally attached the "Local" ground feed to the outside and got it working.