Toshiba 32DT2U1 has 5v but no stby LED, wont power on

[triplefour]

got a Toshiba 32DT2U1 here that wont turn on.
i took it apart and tested some voltages and saw 5v and even 12v but pushing power button does nothing. no red standby light. nothing.

im thinking power supply problem but still not skilled enough to chase it down myself apparently :/

i have 165v at the main filter cap.
i will measure the voltages at all the connectors and post soon

[stj]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

check the voltage at the cathode of d203
i think that's gonna be the standby supply.

if you dont get a voltage, try replacing the 2 small caps surrounding what i think says U501

[budm]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

"i took it apart and tested some voltages and saw 5v and even 12v " If you are getting 5V STBY, then U501 is working.
You need to check the DC voltage at the 'PWR' (ps_on) pin, it should be <1Vdc when TV is not turned on, >2V when power switch is,activated, same for INV pin. The 24V will be there when PS_ON is present and if the 12V/24V SMPS circuit is functioning.
Since you indicated that you do have 12V, that means the 24VDC for the inverter board must be working then, so the PSoN must be present at this point if what you are saying is correct.

[triplefour]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

well thats strange. now the green power LED comes on when i push power. i guess there isnt a red standby LED.
anyway in standby i get 0v on all the pins except the 5v
when i turn on the power i get the 5v and the 12v, and also where it says INV i get 3.3v
that doesnt seem like enough to power an inverter...is this the problem?

on cathode of d203 i see 5v in standby and when powered on

what is DIM? that is 0 in both cases
and ACD is like .06v
PWR is 3.3v when power is on

[triplefour]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

ok i was being dumb the 3.3v on the inverter pin is just telling the inverter to turn on.
i see 26v on the connector that goes to the inverter, and the inverter side connector.
i notice DIM is there again and i see 3.3v on the inverter side but oddly, 0v on the PSU side?
so the inverter is getting 26v but i am seeing no backlight flashing

[budm]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

OK, let get this straight again when power switch is activated:
What do you have on P802:
5V: ??? This one should be there ALL THE TIME.
12V: ???
PWR: ???
INV: ???
DIM: ???
ACD: ???

P803:
24V: ???
INV: ???
DIM: ???
ACD: ????

[stj]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

apart from the real issue, you may have a bad led, i'v seen that on an LG the other week.

[triplefour]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

P802
5v: 5v
12v: 12v
PWR: 3.3v
inv: 3.3v
dim:0
ACD:0.6v

p803:
24v: 24v
inv: 0
dim: 0
ACD: 0


but im not getting anything now. it went back to not turning on the green light.
im stuck in 5vstby...

it was doing strange things. earlier it was stuck in green light mode and i couldnt turn it off. as soon as i plug in the power the green light would come on and i had to unplug the set to get it to turn off.
now it wont turn on again.
for a moment there it was working almost normal. plug in, turn on, turn off... i was about to test if i could hear audio when it started bugging out..
is this now looking like motherboard issue?

[triplefour]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

now it seems like it is stuck in on mode when i plug in the power, but the green LED does not come on. all voltages are present though!
also earlier it was doing a thing where it seemed halfway normal. when plugged in, no green light, then press power green light comes on...wait a few seconds and the tv turns off by itself. it did that a few times then went back to being stuck on...

[budm]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

1) So PWR is stuck at 3.3V and when power switch is toggle on and off it does not change state?

2) That inv 3.3v on P802 but not at P803 is not right since the connection of the INV pin of P802 is connected directly to inv pin of P803. The power supply board is used as junction point only to transfer signal from main board feeding into P802 and come out at P803, it is done like that to make clean wiring. So you need to verify that.
It seems to me you may have main board problem. Is board hit by surge or lightning? What is the history of this TV?

[triplefour]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

no idea on the history of the TV.
power is stuck at 3.3v i have monitored it while pressing the power button.
dim is 0 on both connectors
inv is .25v on both connectors.
i must have been seeing zero cuz i was on 200v on my meter or something....

[budm]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

If the PWR signal is stuck and cannot be toggle HI/LO by power switch, then it is the main board problem. Then you need service manual to find out how that PWR signal is generated.

[mmartell]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

The mainboard is remembering its last state (on) but probably malfunctioning beyond that. Any voltage regulators on the mainboard ?

[triplefour]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

yeah there are some... guess i better test em

i see on ebay an eeprom chip for sale and the problem they say it fixes sounds kind of like one of the things it was doing (though it was mostly doing other things)

" Toshiba 32DT2U1 TV that experiencing intermittent or permanent dead set

failure symptoms

When the TV is turned on, the green LED lights up for 3-5 seconds, then whole TV shut down with no display. This will happen more and more frequently until finally completely dead
Only is an EEPROM Programmed

The eeprom you receive may be different from your original but it is a compatible replacement.
All sales are FINAL and NO RETURNS will be accepted. "


:/ and i really cant find a service manual...

[stj]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

these random problems could also be caused by ripple due to bad caps - i take it you dont have a scope.

[triplefour]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

nope no scope..
how would i tell if that eeprom is bad before gambling $11?
http://www.ebay.com/itm/EEPROM-FOR-T...item3ce1824fe7
heres the pictures of the regulators. voltages coming soon

[triplefour]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

ok heres the voltages
N28A
9117-50
1)0
2)5
3)11.93

M503
1117-33
1)0
2)3.3
3)5

N282
G1084
1).54
2)1.79 (-.54 = 1.25 so this ones good)
3)5

N271
G5694
1)5
2)0.8
3)0
4)0.8
5)0.5
6)0
7)1.19
8)5

EEPROM
1)3.3
2).02
3).18
4)0
5)0
6)0
7)3.3
8)3.3

B20
P03
CDF0415
1-4) 11.9
5)0.4
6)0.4
7)0
8)0.4

need to lookup datasheets on the IC's but the regulators seem fine to me.

[triplefour]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

i cannot find the datasheet for N28A 9117-50 no matter how i break it up...
seems like a normal 5v-12v regulator though

cant find N271 G5694 either...

cant find the b20 p03 cdf0415 either...

grr

[stj]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

it's not so much about the voltages, as how stable they are.
they should not fluctuate.

[triplefour]

Re: Toshiba 32DT2U1 has 5v but no stby LED, wont power on

well then no nothing is fluctuating...also i dont understand how i can have all voltages present and still not even see a flash of backlight?