Telo resets on incoming call

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peabody
Posts:133
Joined:Wed Feb 20, 2013 10:02 pm
Telo resets on incoming call

Post by peabody » Thu May 26, 2022 10:23 am

I have a telo model 110-0110-252. I can make outgoing calls with no problem. But if I answer an incoming call, I get a buzz sound on the phone, and the caller just hears continuous ring - and my Telo resets as though it had just been powered up. The reset completes normally, but I can't receive calls, and each attempt produces a reset. I do get normal ringing on the phone, and if I don't answer, it goes to voicemail, which works normally. I hear the voicemail being left, and I am able to listen to the voicemail, ,and delete it, on the Telo. But if I pick up the phone on an incoming call, everything goes haywire.

Can anyone help?

peabody
Posts:133
Joined:Wed Feb 20, 2013 10:02 pm

Re: Telo resets on incoming call

Post by peabody » Thu May 26, 2022 11:09 am

Further information that may help. I tested the power supply, and found that it delivered 5.17V with no load. But then I rigged up a circuit that placed a 20-ohm resistor across the power supply output, and the voltage went down to 4.16V. That's only 250 mA, and the supply is rated 5V 2A. Reducing the resistor to 10 ohms (500 mA), the voltage dropped to 2.8V. It seems to me this is the likely explanation for my problem. Apparently the Telo still doesn't draw much current even when generating ring voltage, but something must happen when answering a call that draws a lot of current (maybe a relay), and that causes the voltage to drop enough to trigger a reset.

If this makes sense, then I just need a new power supply. Does anyone know of a source where I could find one locally in the US - Walmart, BestBuy, Home Depot, Lowes? I see them on Ebay, but that's a week away.

Also, if I could get inside the Telo, I could temporarily rig up a 5V supply that I know is good and see if that fixes it. How do I get the Telo open?

peabody
Posts:133
Joined:Wed Feb 20, 2013 10:02 pm

Re: Telo resets on incoming call

Post by peabody » Thu May 26, 2022 1:35 pm

Ok, I have confirmed that it's the power adapter that's gone bad. I took the Telo apart and soldered wires to the power connector terminals, then hooked those wires to a known good 5V power supply. And now everything works again. So now I have to find a permanent replacement for the power adapter. I found about 20 on Ebay that reference the part number on the Ooma adapter, but none of them say what the current rating is. I suspect that's because it's a good bit less than the 2-amp spec on the original. Can anyone suggest a source for an adapter that works?

MLXXXp
Posts:122
Joined:Mon Feb 11, 2013 5:46 am
Location:Toronto, Canada

Re: Telo resets on incoming call

Post by MLXXXp » Thu May 26, 2022 4:27 pm

Well, since it appears you have the ability to solder, if you can't find a supply with the same connector, buy any adapter rated 5V and at least 2A, then solder the connector from your failed supply onto the new one.

peabody
Posts:133
Joined:Wed Feb 20, 2013 10:02 pm

Re: Telo resets on incoming call

Post by peabody » Thu May 26, 2022 8:46 pm

Using the temporary good supply, I inserted an ammeter into the circuit to measure the current draw. The Telo idles at about 1A. While making an outgoing call, or when the phone is ringing, that goes up to about 1.25A. But if I answer an incoming call, there's a big current spike that appears to exceed 2A, but which goes away very quickly. So I decided to get a 3A adapter, or at least one that claims to be 3A:

https://www.amazon.com/gp/product/B08HT1HKJ3/

I'm not sure that's really necessary since the original 2A adapter has lasted about 10 years, but it was just a few dollars more.

I still don't understand why there would be a current spike when answering an incoming call, but not when picking up the phone to dial an outoing call.

I tried to open the old adapter to replace the (I would guess) bad electrolytic capacitor that's causing the problem, but couldn't find a way in with my spudger. Unfortunately, I don't have a heat gun.

peabody
Posts:133
Joined:Wed Feb 20, 2013 10:02 pm

Re: Telo resets on incoming call

Post by peabody » Fri May 27, 2022 9:43 am

The current spike I saw yesterday was consistent behaviour over a number of incoming calls. But today the spike has disappeared. Same power supply, same phone, but no spike. So either the Telo healed itself, or the firmware was updated overnight. Anyway, it's fixed aas far as I can tell. I do get a 2Hz flashing red light on the bottom of the main board which wouldn't be visible if the case were closed. I don't know if that means anything.

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