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Yet another 616 problem

Started by m1898, December 18, 2013, 08:08:46 PM

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m1898

Okay, did the voltage test. On the exts that the 7130 didn't work, voltage was around 13 v no load. When 7130 plugged in to the same block, voltage dropped to just over 1 volt. On the exts that the 7130 worked on, the voltage stayed around 13 v, both load and non load. Does this info help anyone?    Jim
"Oh lord it's hard to be humble, when you're perfect in every way. I can't wait to look in the mirror, I get better looking each day"

unbeldi

#16
Quote from: m1898 on December 19, 2013, 12:29:21 AM
Okay, did the voltage test. On the exts that the 7130 didn't work, voltage was around 13 v no load. When 7130 plugged in to the same block, voltage dropped to just over 1 volt. On the exts that the 7130 worked on, the voltage stayed around 13 v, both load and non load. Does this info help anyone?    Jim
Well, there is your problem.  Voltage should stay up at 13V. I'll ponder the problem.
On the version 3, all components for the station ports are on main board A, the SLIC board. In version 2 they used separate little circuit boards soldered by one edge to the main board for each port.

When looking at your board you should notice the circuit areas for each port, labeled A - P. Ports 19-26 (did I count that right?) are one group most to the right hand side. So there must be a component that is common to 11-18.

Another useful measurement would be to measure the same supply voltage on, say port 11, when the phone is connected to, say, port 18, and some additional measurements of this sort depending on the results obtained.  This might help locate the failing part, or narrow the search.




m1898

#17
Volt meter hooked to ext 11, pluged 7130 to ext 26, no drop in voltage. Problem must be in left side of board.
Getting closer. Now if I can just find a schematic for it. Thanks. Jim
"Oh lord it's hard to be humble, when you're perfect in every way. I can't wait to look in the mirror, I get better looking each day"

unbeldi

Quote from: m1898 on December 19, 2013, 01:29:37 AM
Volt meter hooked to ext 11, pluged 7130 to ext 26, no drop in voltage. Problem must be in left side of board.
Getting closer. Now if I can just find a schematic for it. Thanks. Jim

Plugging the phone into #26 is not that informative, as you already found that port to be working.
The reverse test is better, phone on 11 and meter on 19 to 26.
Next, test combinations of ports in the lower, bad group. Likely the two groups have separate power supplies traces, and perhaps it's a by-pass capacitor that fails under load.

I have a circuit diagram, but it is not complete. Poor scan of the large pages.

m1898

After I did the above post I realized that wasn't enough data. I went through and tested all the other exts with the meter hooked to 11. Exts 19-26 had no drop. When I tested 12-18 I had the voltage drop. I had to hit "reset" to test each ext, (12-18) as the voltage was slow to build back up. Sorry to be so much trouble.  Jim
"Oh lord it's hard to be humble, when you're perfect in every way. I can't wait to look in the mirror, I get better looking each day"

Phonesrfun

Speaking of traces on the power supply,

When I got mine, the whole dang thing was behaving weirdly.  It looked great from the outside and there were no apparent smashed corners on the box it was shipped in.  I contacted the seller and she refunded me the money, but said to keep the 616 because at the price I paid for it, she did not want to incur the shipping cost back to her only to have a dead unit.  At that point I decided to open it up and have a look.

What I found is the power supply board had cracked and I believe three printed circuit traces on the back of the board had broken along with the board.  A transformer which weighs a lot for that board is mounted directly to the board with no support beneath it.  Apparently in shipping, just the forces of a UPS handler or two of tossing the box around was enough for the weight of the transformer on the boad to break the board.

For me, it was a simple matter to disconnect the connectors, remove the board and repair the traces by just soldering a short piece of wire over the breaks in the traces.  I also put some styrofoam under the board once I got it back in the 616 cabinet to keep it from happening again just from what little jostling around I would do to hang the box on the wall.

It worked great!  It has continued to work, now about 4 years later.

So, if you are inclined, open it up and take a look at all the power supply traces.  The mother board is another issue.  The power supply board is not dense at all and the traces are easy to repair.  The main board is dense and would be a bearcat for a novice to try to troubleshoot.

My money, however, is on the power supply board.
-Bill G

unbeldi

#21
Quote from: Phonesrfun on December 19, 2013, 01:58:54 PM
Speaking of traces on the power supply,

...
A transformer which weighs a lot for that board is mounted directly to the board with no support beneath it.  
...

My money, however, is on the power supply board.
I don't think so. His board seems to have proper power, half the board is working, and the switching matrix works. The analog switching matrix is digitally controlled by a central processor, so that seems to be ok, since he could make and receive calls using analog telephones.

Also the transformers of a version 2 and 3 board are not mounted on a circuit board anymore, but rather on a separate metal bracket attached on the case. I think you have a KX-T616, in this case it is a KX-T61610-1.

unbeldi

#22
Quote from: m1898 on December 19, 2013, 01:51:02 AM
After I did the above post I realized that wasn't enough data. I went through and tested all the other exts with the meter hooked to 11. Exts 19-26 had no drop. When I tested 12-18 I had the voltage drop. I had to hit "reset" to test each ext, (12-18) as the voltage was slow to build back up. Sorry to be so much trouble.  Jim
No trouble.

The top main board contains the circuitry for the intercom stations and their digital control. The digital functions are handled by two processor chips, one for the first eight extensions, and another for the second group of eight.  IC300 controls extensions 11-18, and IC301 is for 19-26.

So, your failure is cleanly along this division and it is highly likely that one of the data processors has failed or a component that supplies/controls power to the chip.

Each extension port has a protection circuit that I think is controlled by the processor, once triggered, I think a reset is needed for the port to work again. I have observed the same behavior you're describing on a version 2 board that I recently worked on.

m1898

So basicaly, as long as it still works with my old phones, just deal with it. I bought this as a backup unit in case my other one had problems, so not a big deal. Thank you for all your help. At least now I have a better understanding of the problem.                  Jim
"Oh lord it's hard to be humble, when you're perfect in every way. I can't wait to look in the mirror, I get better looking each day"

TelePlay

This topic thread was a good insight into the workings of a "616" and thanks to everyone who contributed.

Phonesrfun

Quote from: m1898 on December 19, 2013, 05:04:09 PM
So basicaly, as long as it still works with my old phones, just deal with it. I bought this as a backup unit in case my other one had problems, so not a big deal. Thank you for all your help. At least now I have a better understanding of the problem.                  Jim

Probably so.

Although I have a programming phone with my 616, mine is still set up with the defaults and it suits me just fine.
-Bill G

unbeldi

#26
Quote from: m1898 on December 19, 2013, 05:04:09 PM
So basicaly, as long as it still works with my old phones, just deal with it. I bought this as a backup unit in case my other one had problems, so not a big deal. Thank you for all your help. At least now I have a better understanding of the problem.                  Jim

Well, if I had the unit, I wouldn't give up just yet.  You mentioned that analog phones work just find on the 'bad' ports, so this means that the IC300 is not dead completely. As part of extension control, it performs off-hook detection as well for its set of ports and if that weren't working you could not make any calls.

Something is broken that is triggered simply by connecting a phone to the data pair on the ports. As a next step I would try to test the nature of this failure, and connect simply a resistor across yellow and black, perhaps a couple kilo-ohms in value and if that is too high to cause any effect, go lower.  This would test whether the failure is purely an analog power problem, or whether it is a digital communications failure that is shutting down the chip or the ports.  Comparison of the behavior with the good ports might be interesting.

PS:  I just measured the on-hook current draw from a KX-T30830 phone on the data pair. It was 21mA at 12.5V supply. So the internal resistance of the phone is about 600 ohms.  So that would be a good lower value to use for the resistor test I just mentioned.

m1898

I haven't comptetely given up, it's just that I'm not that good at traceing down complex problems in electronics. I can replace some componets, checck for opens and shorts in most cases, and other easy to find problems.
If people still want to give me ideas please do so. I will print out these pages to have for reference in trying to figure this out. The responses have been a big help, I have learned a lot about this unit. Thank you,  Jim
"Oh lord it's hard to be humble, when you're perfect in every way. I can't wait to look in the mirror, I get better looking each day"