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Author Topic: Obi110 plus SPA8000 as Poormans Analog PBX  (Read 25484 times)
stooba
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Posts: 13


« Reply #20 on: April 07, 2012, 06:53:31 pm »

That would be great.  The trouble is that such small SMD devices are often very difficult to identify, especially ones without markings. Still, any info might help.

The components that I'd like to identify are:
   K1 - a relay (DPDT)
   Q206 - a transistor (likely a MOSFET of some sort to activate relay coil)
   C99 - capacitor (likely power conditioning for relay coil)
   D150 & D151 - diodes (polarity of PHONE/LINE Ring and Tip lines)
   D203 or D204 - diodes (for back EMF on relay coil)

Since the relay is missing, Resistors R38 and R39 are added as jumpers that connect the COM and NO pins to look as if the relay was present and activated all the time.

In the mean time, I am going to ask the Obihai support team for this information as well.  I've yet to deal with them, so I don't know how helpful they'll be.  I'd hope that they'd be willing to support me since this was their bad decision that I am trying to correct.  Maybe they'll offer to swap out my units with some that are properly populated.  Fingers crossed!
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infin8loop
Full Member
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Posts: 219


My code doesn't abend, it loops to ∞


« Reply #21 on: April 07, 2012, 07:06:25 pm »

Perhaps someone with an Obi that has a relay can take pictures and you can compare.

Maybe the "Owner of the 1st OBi110/100 units in service in Canada & South America" should volunteer. I bet that Obi110 has a relay!   Grin
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"This has not only been fun, it's been a major expense." - Gallagher
QBZappy
Hero Member & Beta Tester
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Posts: 2322



« Reply #22 on: April 08, 2012, 07:51:05 am »


Relay

This is a picture of the relay switch inside of my OBi. Dose yours look the same?   Grin

http://www.kpsec.freeuk.com/animated/relay256.gif
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Owner of the 1st OBi110/100 units in service in Canada & South America. 1st OBi202 on my street. 1st OBi1032 in Montreal.
infin8loop
Full Member
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Posts: 219


My code doesn't abend, it loops to ∞


« Reply #23 on: April 08, 2012, 09:07:56 am »

LOL QBZ.

I guess they use different relays for the US and Canadian markets because my relay doesn't look anything like your relay:

http://infin8loop.freevar.com/sharedphotos/RELAY.jpg


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"This has not only been fun, it's been a major expense." - Gallagher
QBZappy
Hero Member & Beta Tester
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Posts: 2322



« Reply #24 on: April 08, 2012, 10:08:49 am »

LOL QBZ.

Infin8,

Hi there friend, I guess we are on a first name basis now.  Cheesy

Happy Easter all--
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Owner of the 1st OBi110/100 units in service in Canada & South America. 1st OBi202 on my street. 1st OBi1032 in Montreal.
stooba
Newbie
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Posts: 13


« Reply #25 on: April 13, 2012, 08:07:04 pm »

Hey again.
Is there really no one out there who has an OBI110 unit who is willing to take photos of the relay and components that are missing from the current builds?
Seems like there should be some units out there.
 Huh
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MichiganTelephone
OBi110 Beta Testers
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Posts: 484


« Reply #26 on: April 13, 2012, 10:32:10 pm »

Hey again.
Is there really no one out there who has an OBI110 unit who is willing to take photos of the relay and components that are missing from the current builds?
Seems like there should be some units out there.
 Huh

Just because people have such units doesn't necessarily mean they want to disassemble them.  On the bottom of my OBi110 (which I am sure has a relay) there are no visible screws, and I sure don't want to start prying off feet or punching holes in the label to find them.

However, I am wondering if you aren't going about this the hard/expensive way.  Since you seem to know something about electronics, wouldn't it be possible to use a low voltage, low current DPDT relay (with the coil of the relay connected to a "wall wart" transformer) to switch your phone line?  I know it would be nicer if it were built into the device, but since it isn't, it just seems like an external relay solution might be cheaper and easier to build than trying to track down a bunch of unknown components.

The way I picture it, such a relay would have eight contacts, two for the coil and six for the DPDT switch. So:

The coil contacts would connect to a low voltage transformer plugged into the electrical supply.

The DPDT switch center contacts would connect to the phone (replacing the PHONE port).  You'd probably want to connect these to a standard phone jack so you can plug your phone in.

The DPDT switch normally closed (when no power is applied) contacts would connect to the PSTN line (which would also be connected to the OBi110 LINE port).

The DPDT switch normally open (when no power is applied) contacts would connect to the OBi110 PHONE port.

So, as long as power is available, the phone would connect to the OBi110 PHONE port through the relay's normally open contacts, and when the power drops it would connect to the phone line via the relay's normally closed contacts.  If you use a low-current relay with a low-voltage AC coil, and an AC transformer (not DC) you probably don't really need to worry about kickback protection, since there are no rectifiers in the power supply to protect.  Of course you could use a relay that has a coil that matches the local power supply voltage (such as 110 volts in the USA and Canada) but I don't recommend that because then you'd have to be VERY careful to not let the relay coil contacts and the switch contacts come in contact with each other.

With smaller relays it may be a bit difficult to keep the two circuits isolated so that's why I would consider using a "wall wart" to step down the AC voltage, but of course if you have a larger old-style relay that puts plenty of distance between the coil contacts and the switch contacts it might not be such an issue.  BUT since I don't know who might be reading this, as a general rule I would say you should NOT use higher voltages (probably anything above about 24 volts) for the relay coil voltage unless you are VERY EXPERIENCED with electrical devices and know the dangers of dealing with the higher voltages (which can include fire or DEATH if you are not careful or don't know what you are doing!).

I really do "get" the desire to not have to use an external relay and to fill in the "missing" components, but sometimes you just gotta be practical and use what you know will work and what is available.  In fact I wonder if the reason the relay is missing in the first place is because it was made in Japan and the factory that makes them was damaged in last year's earthquakes, causing a shortage (similar to what happened with hard drives)?
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Inactive, no longer posting or responding to messages.  Goodbye and good luck.  Some of my old Obihai-related blog posts have been moved to http://tech.iprock.com - note this in NOT my blog; I have simply given the owner permission to repost some of my old stuff.
RonR
Forum Member

Posts: 4528


« Reply #27 on: April 13, 2012, 11:18:14 pm »

stooba,

The relay that you're missing isn't simply engaged by the presence of power to the OBi.  The relay is controlled programmatically by the firmware and is engaged only upon the OBi becoming operational, not by simply being powered up.  This results in the OBi PHONE Port being connected to the PSTN line in the event the OBi doesn't start up or later crashes due to a hardware or software failure, even though the unit has power.  Consequently, an external bypass relay based solely on the presence of power won't be nearly as effective.
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stooba
Newbie
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Posts: 13


« Reply #28 on: April 14, 2012, 07:27:20 pm »

Thanks to both of you for your comments.

MichiganTelephone,
You're absolutely right.  I could rig up an external relay setup to provide the same power-failover feature.  But it actually is a lot more work than just populating the correct components on the PCB.  If I can find out what relay is being used, I can certainly determine what driving circuit would best trigger it (I'm an electronic engineer by trade).  I could probably spec in my own replacement relay, but it would be best to use the one that the designers had in mind in the first place.

Taking apart the Obi110 is extremely easy.  One screw under each of the four rubber feet.  And the feet are very easy to remove and put right back on.  I've had mine apart at least a dozen times already and it goes back together perfectly.  Once open, the PCB is just sitting in place, not even any screws holding it down.  Just tip the unit upside down and the board will fall out.  If you are in a dry climate, be careful about static, but overwise you can just take some photos of the relay and the components I've indicated on both sides of the board.  Then slide the PCB back into place - guide the jacks toward the holes in the case and drop the rear end of the PCB into place.  Easy-peasy!

You might be right though.  I might not get the answers I'm hoping for.  There might not be anyone willing to open up their unit to take the photos, or their photos might not give me enough information to decipher the circuit.  But, I try to be optimistic that my fellow techies will come through.

RonR - That is my understanding too.  I'm hoping that by replacing the actual components on the board, I will reactivate not only the power-failback feature, but some of the other failure modes as well....maybe even the ethernet failback.  One potential issue could be that they disabled the code in the controller that actually activated the pin that tripped the relay in the first place. 

I have been pulled away from this project for the last week, but will keep trying to get answers from Obihai next week.  I'd really like to understand their reasoning for deactivating this feature.  Didn't it work as planned?  Did it cause other issues with operation of the device?  Was it purely a cost saving measure since relays are a bit pricey?  We may laugh at the idea of a $0.25 relay being considered pricey, but in mass manufacturing it is.  I had a friend who worked for a huge Telecom company and his whole salary was justified by being able to shave ten cents from the manufacturing cost of their phones.

Anyhow, there might be other work-arounds to provide partial solutions, or I might do all of this and find out that the device doesn't work correctly even with the components repopulated.  But this topic seems to be popping up on other threads and I'd like to be able to provide a definitive answer once and for all.

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RonR
Forum Member

Posts: 4528


« Reply #29 on: April 14, 2012, 08:04:18 pm »

I'm hoping that by replacing the actual components on the board, I will reactivate not only the power-failback feature, but some of the other failure modes as well....maybe even the ethernet failback.

I think the logical fallback features were never implemented because of the chicken-and-egg problems they create.  If you drop the relay because of networking or provider failure, your phone is disconnected from the OBi and you can't ever get to the IVR to diagnose things, set a static IP address, or anything else.  You'd have to have a switch or something to force the phone to be re-connected to the OBi.  It's a flawed idea, which may be one of the reasons the relay was abandoned.

One potential issue could be that they disabled the code in the controller that actually activated the pin that tripped the relay in the first place. 

They'd have to at least activate the pin unconditionally somewhere in the initialization code or else revision 2.8 boards wouldn't work.  It's pretty clear from the relay's behavior with the latest firmware that nothing has been changed.  I can't believe they'd check the hardware revision and do something different for a non-existent relay.
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Shale
Hero Member
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Posts: 1061


« Reply #30 on: August 08, 2013, 08:05:27 am »

Confirming Stooba info:  K1 is the spot for a relay. R38 and R39 are jumpers that close the path for the N.O. contacts. These would be removed if a relay were to be installed.
RF150 and RF151 are fuses that connect the Line to the swingers on the contacts.



I see gary-gary (who may have gotten the info from another post) identifies the relay in http://www.obitalk.com/forum/index.php?topic=6413.msg40769#msg40769 as  K1 - TX2-4.5V (Panasonic)

That relay's pins are on a 0.1 inch grid and that relay is available from distributors.
« Last Edit: August 11, 2013, 09:07:21 am by Shale » Logged
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