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Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809 -
Re: What is telephony? where does the VCC come from?
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 SP483ECLast edited by keeney123; 01-08-2016, 12:44 AM.Comment
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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.Comment
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Re: What is telephony? where does the VCC come from?
Here is the work I have done while the site has been down.Attached FilesComment
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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.Comment
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Re: What is telephony? where does the VCC come from?
surface-mount electrolytics on 10year old gear - hmm....Comment
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I have two TCL A30 phones.
Old Phone: This phone worked fine for years, then stopped charging If you plugged a charger into it, the phone would make the charging sound, the phone would tell you it is charging, but the battery icon would not have the charging symbol in it and the battery would not charge.I tried new battery, same behavior.
New Phone: Works fine, bought as a donor board to try and repair Old Phone
My interest here is to repair Old Phone, using components parts off New Phone if needed. I am not interested in replacing Old Phone with New Phone.... -
To you programmers out there I want to know if it is possible to put a new OS on the Sonim XP5s phone? I only need this phone to make calls, receive calls, have a list of contacts and be able to call voice mail.
I bought this phone new Sep.2021 as an unlock phone from a third-party seller. The phone worked fine until Jan 2022. I then had intermittent problems with the sound setting resetting itself. One of the settings, outdoor, would go to silent all by itself. When in silent mode it does not indicate a call has come in. I missed very important phone calls. All the other setting in sound... -
Hi all,
Got this smart phone free from a guy who dropped it hard until the lcd display cracked with no seen display.
Opened it and found the display ribbon cable partly damaged. I charged the phone full in 2 hours time, the led red light turns to green indicate full charge.
Then i use a usb cable connect the phone to laptop but it only showed as media player with firmware version. Too bad there is no option to check folder.
Does anyone know any method to check if the phone is working good? Looking forward for any advice and help possible.
If tested the... -
Good day folks. I had a little f-up over at my new shop today and it made me pretty angry, but at the same time it determined me to try and figure out what could've happened there. This is only going to be a speculative discussion since I don't know the exact layout of our network, hence I don't know what's going on past our room. So:
The repair shop where I sit is situated in a remote building down the street from the main building. There's a Cisco IP phone in this room, a 7911, like the rest of the company uses. There's obviously some sort of networking going on between the two... -
Nokia C2-01 RM-721 RM-722 Phone Schematic
The Nokia C2-01 RM-721 RM-722 was a mobile phone produced by Nokia. The Nokia C2-01 supported 3G and had a 3.2 megapixel back camera. It had a single SIM card. The handset was introduced to the markets in 2011. It replaced its predecessor, the Nokia 2700 classic and Nokia 2730 classic and has improved specifications....11-05-2024, 07:40 AM
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