What is telephony? where does the VCC come from?

[stj]

Re: What is telephony? where does the VCC come from?

surface-mount electrolytics on 10year old gear - hmm....

[keeney123]

Re: What is telephony? where does the VCC come from?

How I would proceed with this problem is find out why the relays are turning on when you are not introducing the 110 AC Volts. How does the micro controller sense the 11O AC. Does the 110 AC turn the relays on or does the micro controller turn on the relays. The relays have coils that energize the relays. I would start there to find out what voltage is across the coils to the relay. Once you find that out this voltage you will be able to trace it back to find out what is turning it on.

[scampo77]

Re: What is telephony? where does the VCC come from?

Here is the work I have done while the site has been down.

[scampo77]

Re: What is telephony? where does the VCC come from?

Boy am I ever happy this site is back up and running!! I cant seem to attach pictures, but at this point beggars cant be choosers. I have complex photos of my measurements at all ICs, and important transistors and I have measurements from the working corroded board and the failed non corroded board I would like to repair. Unfortunately I cant post photos right now.

Some progress while this site has been down, but mostly bad news.

I have found a different logic board from a donor assembly, I was using it for just parts but out of desperation I just plugged it in and it seems to be working. This is good news because now I have measurements for some kind of a side by side comparison. This board is really corroded and will be very unpredictable if I were to put it back into service. So leaving the crusty board isn't an option and fixing the old board would sure be nice.

#1 problem, my logic board seems to have something seriously wrong with it. When I plug in the original logic PCB, the board sends a signal from the micro controller to a transistor and energizes 2 relays. These 2 relays look like they are for 110v mains power into the inverter. The way this is SUPPOSED to work is when I introduce 110 VAC, then these relays energize and then this inverter becomes a battery charger. The crusty board does not energize the relays until I introduce 110v.

#2 Problem, neither logic board seem to power up the remote display. I called a inverter repair guy and he told me that the common failures are the lcd screen and static discharge corrosion to the controller in the remote. Usually the buttons still work with either of these scenarios. My buttons do not work. I have ordered the lcd screen it was only $2, I have also ordered another remote board entirely.

I don't know if there is anything I can look at with the microcontroller on the main logic board. I have limited knowledge how to diagnose and repair microcontrollers without schematics, all I know how to do is to verify if I have 3.3v here or ground there.
I have done the best I can, to label as much as possible but I think I will be ordering a new main logic board, unless someone here knows something that can help.

[keeney123]

Re: What is telephony? where does the VCC come from?

The SP483 is a "Low Power Half-Duplex RS-485 Transceiver".

The power supply for this RS-485 IC comes from the 5V LDO regulator. The regulator sees 14V on its input, not the RS-485 IC.

OK I was confused I thought you were saying the rs485 was a part number. Thanks for the clarification. The last RS number I remember is RS-232C

[fzabkar]

Re: What is telephony? where does the VCC come from?

I do not know where the RS485 ic came into play. The picture shows a SP483EC

The SP483 is a "Low Power Half-Duplex RS-485 Transceiver".

The power supply for this RS-485 IC comes from the 5V LDO regulator. The regulator sees 14V on its input, not the RS-485 IC.

[keeney123]

Re: What is telephony? where does the VCC come from?

budm, look at the 4th photo in post #53. The reading of 4.5V appears to be for one of the data pins of the RS485 transceiver IC, not the power supply.

BTW, I agree that the 14V-5V in-out voltage differential is absurdly high, but that's the way it appears to be designed. If we knew the identity of the "15H" part, then perhaps we could determine the allowable input range.

Driver input is max Vcc +.5 volts which is 5.5 volts on pin 4. The max rating of Pin 6 driver output to receiver input is +/- 15 volts. These are the absolute maximum voltages. I would say when turned on a spike of voltage appears. Also VCC max is 7VDC

I would say the 14 volts is another voltage which is not powering the sp4883ec ic. I do not know where the RS485 ic came into play. The picture shows a SP483EC

[budm]

Re: What is telephony? where does the VCC come from?

budm, look at the 4th photo in post #53. The reading of 4.5V appears to be for one of the data pins of the RS485 transceiver IC, not the power supply.

BTW, I agree that the 14V-5V in-out voltage differential is absurdly high, but that's the way it appears to be designed. If we knew the identity of the "15H" part, then perhaps we could determine the allowable input range.

OK, I see it now. Thanks.

[stj]

Re: What is telephony? where does the VCC come from?

volt-drop over that crappy cable must be taken into account by the designers.

[fzabkar]

Re: What is telephony? where does the VCC come from?

budm, look at the 4th photo in post #53. The reading of 4.5V appears to be for one of the data pins of the RS485 transceiver IC, not the power supply.

BTW, I agree that the 14V-5V in-out voltage differential is absurdly high, but that's the way it appears to be designed. If we knew the identity of the "15H" part, then perhaps we could determine the allowable input range.

[budm]

Re: What is telephony? where does the VCC come from?

Double posted.

[budm]

Re: What is telephony? where does the VCC come from?

The remote is fed by 14.7V, not 5V.

I am confused:
Per Post 45 : AISI, the incoming supply at the remote PCB is regulated as follows: per diagram: So RJ-1B is fed by 14.7V? Feeding 14V to drop down to feed LP2951 3V? That is lots of Vdrops on this LDO.

Post 52: So on the main logic board the regulator 295151ACS is a 5 volt regulator because it has no XX numbers after it. The XX numbers would be like -2.5, -3.0. This is the data sheet for that chip.



If this is what is generating your 5 volts regulated to the remote board Then it has very tight tolerances. It you are reading 4.5 volts that would be out of spec. I also noticed that there is way too much solder on these components on the main logic board. I know if a capacitor gets to much heat near its plate you can damage to connection in a way that the cap will appear to work, but it will not perform correctly.

Post 53 'I have enclosed measurements from my suspect 5v regulator and I have rock solid 5.00 VDC.'

So what is the Voltage feeding the Remote Module for sure?

[keeney123]

Re: What is telephony? where does the VCC come from?

GOOD NEWS!!

I found a damaged trace under one of the RJ11 jacks. (photo enclosed) this connected "B" terminal to the fuse. the huge trace I was chasing around turned out to be B+. It is de coupled by a cap and protected by a fuse (look on the previous post photos) I repaired the trace and now I have MUCH better voltages to work with.

Now the "B" terminal is B+ and I have much better voltages on the remote board (photo enclosed).

The inverter is still going into some kind of protect mode. As soon as I apply battery voltage I throw a big relay and it will not power up like it was before. I am hoping this burnt trace is a step in the right direction.

I have enclosed measurements from my suspect 5v regulator and I have rock solid 5.00 VDC.

So now that problem is fixed. We need to concentrate on this new problem. We need to know where the battery voltage is going too on the inverter. It is possible that the relay is held in by another circuit.

[fzabkar]

Re: What is telephony? where does the VCC come from?

The remote is fed by 14.7V, not 5V.

[budm]

Re: What is telephony? where does the VCC come from?

That is good progress, so the remote is fed by 5VDC not AC which makes a lot more sense.

[scampo77]

Re: What is telephony? where does the VCC come from?

GOOD NEWS!!

I found a damaged trace under one of the RJ11 jacks. (photo enclosed) this connected "B" terminal to the fuse. the huge trace I was chasing around turned out to be B+. It is de coupled by a cap and protected by a fuse (look on the previous post photos) I repaired the trace and now I have MUCH better voltages to work with.

Now the "B" terminal is B+ and I have much better voltages on the remote board (photo enclosed).

The inverter is still going into some kind of protect mode. As soon as I apply battery voltage I throw a big relay and it will not power up like it was before. I am hoping this burnt trace is a step in the right direction.

I have enclosed measurements from my suspect 5v regulator and I have rock solid 5.00 VDC.

[keeney123]

Re: What is telephony? where does the VCC come from?

So on the main logic board the regulator 295151ACS is a 5 volt regulator because it has no XX numbers after it. The XX numbers would be like -2.5, -3.0. This is the data sheet for that chip.



If this is what is generating your 5 volts regulated to the remote board Then it has very tight tolerances. It you are reading 4.5 volts that would be out of spec. I also noticed that there is way too much solder on these components on the main logic board. I know if a capacitor gets to much heat near its plate you can damage to connection in a way that the cap will appear to work, but it will not perform correctly.

[scampo77]

Re: What is telephony? where does the VCC come from?

I have found a second non functioning logic board, I have something I can poke and remove parts from to see traces better. please don't comment that the caps are corroded or the solder traces are bad. I am dissecting this one with the intention of throwing it away when I am done with it.

I have removed all of the RJ11 jacks on this donor board to better see the traces. this "B" port seems to go to the neighboring RJ11 port for the auto start module which I do not have hooked up. then it goes to a capacitor then to me it looks like ground, it takes off and goes all over the place on both sides of the board.

I am now getting 0vdc at the "B" terminal that I am chasing around. And I am getting 4.5VDC on terminal "D" with or without the remote board attached

I have tried calling multiple repair centers and Magnum directly with all of the power of my charm and non of them have access to diagrams or schematics or any engineering side of these repairs. These have been designed to be replaced like computer video cards, the only downside is that the logic board is $400 and the remote board is about $300 and the entire inverter is about $2000. All of these options are way out of my budget.

[keeney123]

Re: What is telephony? where does the VCC come from?

Just one more thing. While your troubleshooting this circuit keep in mind that why the two boards are not talking to each other is because the voltage on the communication chip on the remote is not getting at least 4.75 volts. Right now it has nothing to do with the communication lines between the two boards. A good procedure to follow is check voltages first. Then check the control lines. Lastly check the data and address lines. At all possible have a schematic in hand.

[keeney123]

Re: What is telephony? where does the VCC come from?

It is difficult of working without schematics. For fzabkar theory you could leave the RJ11 connectors unconnected and follow the voltage as he said to find out if there is indeed a voltage problem on the main board. You did say every thing on the main board was working and only the remote was not working? This is how you trouble shoot a board. You follow one train of thought to see if it is correct and if it is not then you modify you train of thought.