CAP ID and what to replace?

[Mad_Professor]

Re: CAP ID and what to replace?

Yes, these are pretty good. Sorry for the no reply. Was sick for the past week and a half and didn't log-in BCN before that.

Anyways, I'll probably look at it in more detail next week since I have a big project this week and not much time to complete it.

In the mean time, check all of the diodes and zener diodes near the connector (like ZD701, ZD702, D701, and D703). Ceramic cap C767 looks a bit dark. Maybe it's the light, IDK, but check for short circuit.
There's also a transistor that looks slightly darker, but again, I'm not sure if it's the lighting that's causing this. Cant see a designator for it, but it's right next to one of those small electrolytic caps C709 by the connector. The "transistor" I'm referring to is in a SOT-23 package.

I was going to post earlier today but got distracted, also I'm not feeling well, runny nose, cat is sick also.

When I get a chance I'll check those components.

[momaka]

Re: CAP ID and what to replace?

Is this good enough?

Yes, these are pretty good. Sorry for the no reply. Was sick for the past week and a half and didn't log-in BCN before that.

Anyways, I'll probably look at it in more detail next week since I have a big project this week and not much time to complete it.

In the mean time, check all of the diodes and zener diodes near the connector (like ZD701, ZD702, D701, and D703). Ceramic cap C767 looks a bit dark. Maybe it's the light, IDK, but check for short circuit.
There's also a transistor that looks slightly darker, but again, I'm not sure if it's the lighting that's causing this. Cant see a designator for it, but it's right next to one of those small electrolytic caps C709 by the connector. The "transistor" I'm referring to is in a SOT-23 package.

[Mad_Professor]

Re: CAP ID and what to replace?

Leakage current through other components is one possibility. It's rare but I've seen it.


I know you included some pictures on page 1, but to have someone help you trace stuff through the board, you will need many high-resolution pictures of the entire board, front and back. In the key areas near the plug, even the smallest traces will have to be visible.

Is this good enough? Otherwise I will have to contact one of my friends and use their nikon.

[momaka]

Re: CAP ID and what to replace?

Yeah but if it was open why would I only be getting 1.1v on the 3.3v rail at the ir/menu panel? this doesn't make sense.

Leakage current through other components is one possibility. It's rare but I've seen it.

I really could use some help here since I am way over my head here, because I can't read the mess on this board and figure out what goes to what.

I know you included some pictures on page 1, but to have someone help you trace stuff through the board, you will need many high-resolution pictures of the entire board, front and back. In the key areas near the plug, even the smallest traces will have to be visible.

[Mad_Professor]

Re: CAP ID and what to replace?

Could also be an open resistor or open transistor (rare).

Yeah but if it was open why would I only be getting 1.1v on the 3.3v rail at the ir/menu panel? this doesn't make sense. I'm getting 1.1v on 3.3v, PWR and IN pins and 1.1v on the ps_on to the psu so something is just sending volts everywhere, what controls the ps_on?

I get 95 ohms on the pin2/tab of u703 to ground.

I really could use some help here since I am way over my head here, because I can't read the mess on this board and figure out what goes to what.

[momaka]

Re: CAP ID and what to replace?

there is a shorted transistor somewhere or a broken ceramic cap and I'm going to find it.

Could also be an open resistor or open transistor (rare).

[Mad_Professor]

Re: CAP ID and what to replace?

Well I tested u703 with live voltage from left to right

pin 1 = 0.00v
Tab/pin 2 = 3.3v
Pin 3 = 4.9v consistent with 5v coming from the PSU.

So now I'm going to trace the 3.3v to the next component and go from there, there is a shorted transistor somewhere or a broken ceramic cap and I'm going to find it.

[Mad_Professor]

Re: CAP ID and what to replace?

I did a full recap of the board, getting 1.1v on ir/menu panel needs to be 3.3v but not enough to bring the the tv to life. I don't know if this is result of damage done by me, since I had a hell of a time recapping the board, solder was different from left to right, some pop out with ease, others I had keep the iron on or break the cap off and double up on irons. I did alot of damage and burn myself several times in the process, burn quite bit of copper tracks but does not seem to have any continuity issues.

I've notice two 10uf/25v caps near the a/v inputs have no ground but I don't know where they go.


edit:
also ps_on to PSU now has 1.1v.

[Mad_Professor]

Re: CAP ID and what to replace?

I removed the cap c702 just to be sure it wasn't a shorted cap, and this is going to be a very difficult board to recap since I had to break the cap off and heat from both sides with two irons to remove the legs from the holes. No damage to the trace except for breaking the plastic edge of a inductor coil L701 near by.

I need to be precise on what to replace.

I went back and decided to to trace the PS PIN to see what components control it.

I traced PS pin from the main connector on the board to a IC BA9713 or BA9T13 or BA9113, forth digit is not stamp well. I'm looking for a datasheet but I can't find any. On the board it's Q703 and the top right pin might be pin 4 from the marker, it seems to control Q704 *H1A, but I don't know what the pin lay outs are for Q703 and what sends the signal to trigger the PS to full on.

Pin 1-3 seems to go to the 5vSB pin on the main connector and all the other pins on the left of the marker I don't know what they do at the moment since I haven't gotten that far. Getting a data sheet on Q703 would be helpful so I can figure out what they do and where to go from there.

if I can't fix it, I will have to buy a new board that's 100$

[Mad_Professor]

Re: CAP ID and what to replace?

pin 3 to ground no reading, goes to c749 which is a 10v 470uf cap also c750, but I don't know where it goes after that.

[budm]

Re: CAP ID and what to replace?

OK, we now know the followings:
Pin 1 is Ground (I can see it in your picture in post 10).
Pin 2 (output pin, middle pin/big tab on top) has 95 Ohms to ground.
So pin 3 (input pin) what do you have?

[Mad_Professor]

Re: CAP ID and what to replace?

Sorry to hear that.
Pin1 of this U703 is tied to Ground which is correct so your reading is right, nothing wrong with that reading.

but it also goes to 3.3v pins on the panel connector.

I'm a bit confused.

[budm]

Re: CAP ID and what to replace?

Sorry to hear that.
Pin1 of this U703 is tied to Ground which is correct so your reading is right, nothing wrong with that reading.

[Mad_Professor]

Re: CAP ID and what to replace?

So the output is NOT shorted then since it shows 95 Ohms. So at what pin that you see less than one Ohm?

Sorry for long delay in respond I had a family death and I've been busy dealing with that.

To answer your question pin 1 or the leg to the left while being probed to ground on main.

[budm]

Re: CAP ID and what to replace?

So the output is NOT shorted then since it shows 95 Ohms. So at what pin that you see less than one Ohm?

[Mad_Professor]

Re: CAP ID and what to replace?

No, pin 2 (big tab or center pin, they are tied together inside the IC)
When you look at the regulator, with big tab up;
Left pin is pin1 (Adj/ or Ground), pin 2 is the output pin (middle pin or the big tab: tab and middle pins are tied together internally), pin 3 the right pin is an Input pin.
We are looking to see if you have really low resistance between the Big tab and the circuit ground (chassis).

Big tab and/or pin 2, I get 95.2 ohms to the ground pins of the main connector.

I tested it 4 times now and now I've OL 200 range and went to 2k range and I'm getting .111.

[budm]

Re: CAP ID and what to replace?

No, pin 2 (big tab or center pin, they are tied together inside the IC)
When you look at the regulator, with big tab up;
Left pin is pin1 (Adj/ or Ground), pin 2 is the output pin (middle pin or the big tab: tab and middle pins are tied together internally), pin 3 the right pin is an Input pin.
We are looking to see if you have really low resistance between the Big tab and the circuit ground (chassis).

[Mad_Professor]

Re: CAP ID and what to replace?

I am talking about the Big tap (Output pin) of the U703 and Ground reading. You can also see MLC cap C717 ocnnected to the big tab and ground.
Pin 1 of U703 is the ground pin since this is a fixed out put regulator IC.

So you want me to probe pin 3 of u703 to ground pins going back to the psu?
or
big tab going back to ground pins?

Option #3. Freeze spray suspect components. Turn on power supply. Components that are short will instantly condense the freeze spray making them very obvious.

Won't work, if I can't turn it on, unless you mean 5v std_by that I might be able to see something or where it ends.

[budm]

Re: CAP ID and what to replace?

I am talking about the Big tap (Output pin) of the U703 and Ground reading. You can also see MLC cap C717 ocnnected to the big tab and ground.
Pin 1 of U703 is the ground pin since this is a fixed out put regulator IC.

[tom66]

Re: CAP ID and what to replace?

Option #3. Freeze spray suspect components. Turn on power supply. Components that are short will instantly condense the freeze spray making them very obvious.