What is telephony? where does the VCC come from?

[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.

[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

[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?

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

[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.

[scampo77]

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

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

[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.

[stj]

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

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