today my ut300 gave up. the pc light keeps blinking, the phone line led is lit always no matter the phone line is attached or not. this happend suddenly. i tried testing some voltages in capacitors ,they showed near 5 v ( the adapter is 5v output) some capacitors showed around 3 v even after changing other capacitors.. ( i just did it to see if that would change anything..) but its the same behaviour. this modem lived for about 10+years on off use i guess. rip .. but i want to know the reason what caused this. or may be if possible repair it..
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broadband ut300 modem,link light stays on forever and had to restart to get connected
- Thread starter MEGAN
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The board has a number of test points; check the voltages there. For example, TP_3P3VIN with TP_GND should read 3.3v, TP_9VIN should be around 9v and so on. Any of those being lesser by more than 0.2 or 0.3v, I'd say, would indicate adapter weakness.
can you please put some pics and pinpoint it ? i am not aware of the test points ,the adapter used for this is 5v 1amp , searched about the pc lan light blinking like that , one video said its the lan issolation transformer gone bad .. looks like i cant get it online that chip .. also the reason for that could be some lightening they say ,as i did have heavy lightening a day before ..but it was working that time and next day for about a hour or so. but then also the led light of dsl phone line orange light is lit continuous forever even if restart the modem again and again.
this user "ervivek" kinda had the same issue like mine. "Hi All, I have BSNL Home 750 UL Plus plan. My modem is UT300R2U.For the first two months, everything worked fine. But for last almost one month, whenever I turn on the modem, all lights (POWER, LINK, USB) except for DATA indicator light up steadily and instantly. Earlier the LINK light used to blink for handshaking, and then light up steadily. Probably due to this problem Internet does not get connected. I have to switch off and on the modem at least 20-25 times repeatedly before it behaves in normal way. Another thing I have noted is even if I disconnect the ADSL line from modem and then turn it on, same three lights turn on (i.e. LINK light is on even without ADSL line connected).Please help me in finding out the fault. Is the modem faulty (its just 3 months since I got it installed). Or is it signal problem."
It seems they've used the same model number - ut300r2u - for different board versions. Mine looks like above. The flash chip on mine is a 48-pin one, while yours seems to be a SOP8. IC versions too appear to be different. And the board I have, uses a 10v 550ma adapter.
So the next thing I'd suggest would be to google the broadcom chip number (not clear in your photo), find its datasheet, find out which pins are power inputs and check those. For example, the rectangular chip in the middle is RAM chip. In my case it is K4S641632K-UC75, a 64Mb SDRAM chip. As the datasheet shows, the Vdd pin is the first pin (counting from the indent in the corner) and the GND pin is the one directly opposite on the other row. For this model, the naming shows that it is LVTTL and that Vdd should be 3.3v. And for the 48-pin 16Mb flash chip my board has, pin 37 is the Vcc and it needs to be around 3v (2.7-3.6v range). RAM and broadcom processor votages are the important ones, so check those first.
The four pins labeled J5 in your photo (in the top corner, near the red led) appear to be serial port. Check their voltages to confirm TTL or RS232 and then you can try reading them using arduino or some sort of serial to usb converter.
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If yours uses a 5v 1A adapter, it should be easy to rule out any power issues by testing with some suitably powerful phone charger. Connect power pins of the charger (pins 1 and 4 in usb-a) to appropriate points on the board. Check how barrel port is soldered to find out where to connect, if positive and negative terminals are not labeled on the board. Usually in case of the barrel plugs, outside is negative and inside pin is positive.
wow thats some very extensive thing for me to do sir ,i am very novice at electronics ,i just thought may be some parts would be available to resolder into the board. but yes i will try that data sheet thing soon , that broadband chip gets very hot though.thank you for supporting the insight of this board. sir if the lan transformer is gone bad ,anything can be done ? in a vid i saw the lan light was non stop lit up alternative pattern 101010 like in seconds . then he stripped the lan transformer ,then other ports worked for him. but we have just one lan port in our board. but also the dsl line is lit with no phone wire connected or not . i will try that broadband datasheet as you advised first.
i checked the voltages of WINBOND/W9864G6GH-6 they are all good ,those vdd ,vddq according to chip data. but i dont see how i can check volatages for this BCM6332KFBG broadcom chip,i also checked the j5 pins , ground pin is at top and others are 3..3 volts. i have a epprom ch341a.. would this be any use in this matter ? i dono much about arduino
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