Sharp LC-60 DPS-162kp

[toubia]

Hello everyone ,

I am just particular with a small base in electricity, and do not know anything in electronics. it's my first tv that I open it's for someone I know,
So received this tv broken during the day before I think, after opening finds open fuse, c7816 exploded
so I replace c7816 check the fuses resistors restore the power supply again the fuse open.
so I remove R7900, C7816, Z7001, R7002 still short, after Q7801 device. so it was the bridge bd 7001 the problem after more short to the ignition.
but still no 5v stby or other voltage, I dismantled some parts but still at the starting point except for the AC start shorts.
I followed the advice on these subjects:

https://www.badcaps.net/forum/showthread.php?t=56062

https://www.badcaps.net/forum/showthread.php?t=49705

[toubia]

Re: Sharp LC-60 DPS-162kp

I have everywhere 340vdc + - on the hot part, also remove some diodes and the opto, it is to surround in green also ic7903. also the small condo c7906 and now cannot read it nothing on the multimeter.

I have 340v everywhere on the ic7903 5-3gnd. 7,8-3gnd .1,2-gnd. pine 5-7.8. 7.8 -1.2.3.4.5

and voltage also on t7901:

1-2, 3-4 : 340v


I have a multimeter beast and a soldering iron, I am waiting for the ic 7903 from the neighboring country. I suspect the little one will turn into a short circuit from the start but I can't test it I haven't got the device to remove it again and test it on another device of the same kind

a yes I also removed then put back, removed d7950 and also I must remove the mosfet which just below the big tranfo t7601 gives me your reading in all directions



my English is bad.

[toubia]

Re: Sharp LC-60 DPS-162kp

I would like to know where it comes from, where does this 5v stby come from, these good from the t7901 and resort well to the secondary cold side ?? if you can enlighten me




and thanks to the other members and budm for his help and his sharing.

[R_J]

Re: Sharp LC-60 DPS-162kp

You must learn the difference between the HOT GROUND and COLD GROUND when checking voltages. All voltages on the primary (HOT) side use the main bridge rectifier negative (or the negative lead of one of the 68µf/450v capacitors)
You can not use cold or chassis ground, if you use cold ground and check voltages in the primary, you will get the high readings like you are on all components.

Look at the top side of the board, there is a checkered line separating the primary (HOT side) from the secondary (cold side)
The smps ic for the standby circuit is IC7983, this ic drives the transformer T7901 and its secondary connects to D7950 which supplies the standby voltage measured across C7950A & B

[toubia]

Re: Sharp LC-60 DPS-162kp

I put my negative everywhere on the hot side card, big transformer, departure of the negative by the bridge it's good,
the ic smps switch is the 7903, isn't it?


and what voltage should I get as it is as it just happened from 230v ac and 190v to 160v dc should I get the right reading with the right negative?

[R_J]

Re: Sharp LC-60 DPS-162kp

The standby smps ic is IC7903 (your picture is not clear and out of focus)
With 230VAC input. The DC voltage across the 68µf 450v capacitor should be 325VDC

[toubia]

Re: Sharp LC-60 DPS-162kp

hello, the stupid thing that I did not do is to test the 5vstby at the p / n terminal on the cold side after replacing the bd bridge.
the I must replaced:
r7902 51k.
r7002 2k.
c7907 47uf.
c7906 smd 47yf max.
d7950 I read 280 ohm and in diode mode 346 ohm 1 way.
i know if this is good?
and another question about the opto (2561b, gk210) or there is the line, period is the transistor or led side ?.
for me it is transistor why these 3 are mounted on the cold side of origins.
I have only one reading hométre 1 direction side point, line on the 4 the remainder ol.




there I am going to reassemble everything and recover some parts on device for testing, but I hesitate to put these opto or mount them then would even see the ic 7903 not sure that it works well will the reassembly have seen?

before i get my ic maybe it's still good

here the images of a member another model but the same board more or less

[R_J]

Re: Sharp LC-60 DPS-162kp

Here is the datasheet for the optocoupler, they are likely good, Make sure they are installed correctly
Here are pictures of both sides of the board, courtesy Shopjimmy usa

[toubia]

Re: Sharp LC-60 DPS-162kp

hi, with a little delay here I tested last night with everything reassembled except r7002. still the same nothing no t7901 output no stby5v voltage.
by the way a few days ago I measured or it is twisted in green at the level of the ic 7903 side above the card and I had the voltage which made the yoyo between the t7901 pin 2 and on the diode d7905 followed by c7901 after c ' was normal on the other components and 15 v in below the transform the 2 cap and diodes, it was just before deciding to remove this diode to see and ic 7903.
now I say to myself either a component in this area or the IC 7903 which unlocks or transform it into a short circuit I told myself from the beginning.
R.J I received my chip there right now I hesitate to replace this chip if the problem is elsewhere.


now I no longer have these 15v at this level.
question to use this resistor r7002, 2m or k ohm at the start of the self level, I hesitated the placed you are on that this fuse must be closed is it important, because if placed and would make a short no?
afterwards I will check as on the subject of ddjmagic where you intervened (https://www.badcaps.net/forum/showthread.php?t=100150 = to see have these never? I had removed this diodes d 7908 and the others then put everything back.

édit :to yes and I also have a doubt on the r7902 even if I have a reading will see if I replace any time with any resistor for testing.

[R_J]

Re: Sharp LC-60 DPS-162kp

R7002 is likely 2 meg Ω. It is not needed for the power supply to work.

by the way a few days ago I measured or it is twisted in green at the level of the ic 7903 side above the card and I had the voltage which made the yoyo between the t7901 pin 2 and on the diode d7905 followed by c7901 after c ' was normal on the other components and 15 v in below the transform the 2 cap and diodes, it was just before deciding to remove this diode to see and ic 7903.

I don't understand? twisted in green? yoyo?

[toubia]

Re: Sharp LC-60 DPS-162kp

circled in green, around the ic smps and yoyo I don't know how to say in English it is the number which dijoncti which goes up then goes down then goes up, that's it

[R_J]

Re: Sharp LC-60 DPS-162kp

The standby circuit is very simple, here is a similar schematic.

[toubia]

Re: Sharp LC-60 DPS-162kp

R.J thank you for the diagram would see with rested head: =, precisely I base myself and look at the data of the stra6069h.
and a question what is the value (M) of the condo and resistance: mega 6 zero?