tech manual for Insignia TV

[luv2liv]

I have an Insignia TV model NS-50DR710NA17.
where can i find the tech manual to repair it? the only manuals i can find is the user's manual which is not good enough for troubleshooting , checking voltages and connectivity.
the TV picture is still good, but back lighting is very dim and every 10 seconds, the display completely black out for 1 second.

 

[SamirD]

These type of manuals are usually not released to the public. But usually you can find the by searching the model number and 'service manual'. Some third-party sites can have them from users that have uploaded the manual.

 

[sdifox]

Buy a new tv. Backlight and power board going = not worth fixing.

 

[SamirD]

Buy a new tv. Backlight and power board going = not worth fixing.

You'd be surprised how cheap the fixes can be. I could have fixed my older Samsung for $20, but the wife wanted an upgrade.

 

[sdifox]

You'd be surprised how cheap the fixes can be. I could have fixed my older Samsung for $20, but the wife wanted an upgrade.

Power board is easy to replace. Backlight, not necessarily.

 

[luv2liv]

still cant find anything for the Insignia. ouch

 

[SamirD]

Power board is easy to replace. Backlight, not necessarily.

If you don't have to replace it and just fix something simple, it can be very cheap.

 

[sdifox]

If you don't have to replace it and just fix something simple, it can be very cheap.

I saw a 55" 4k tv for like 330 recently.

 

[SamirD]

I saw a 55" 4k tv for like 330 recently.

I think I bought our new one for that much. But if I had time to fix our old one for $20, I would have done that instead if the decision was solely up to me.

 

[sdifox]

Lol scepter 50" 4k is 200 at walmart now

 

[mindless1]

The way LCD TVs are modular, it is usually not necessary to have a service manual.

First, have you opened and inspected it yet? A large % of the time, if you still have an intact (non-corrupted) image, OR the opposite extreme that it fails to turn on at all, there will be something visible, like popped capacitors or a bad solder joint.

Short of replacing the entire mainboard, TV repair is usually quite cost effective, costing less than $10 to replace discrete components, assuming you can solder.

The regular interval of 10 seconds then blackout suggests to me a bad solder joint, repetitively heating up, cooling down.

 

[luv2liv]

The way LCD TVs are modular, it is usually not necessary to have a service manual.

First, have you opened and inspected it yet? A large % of the time, if you still have an intact (non-corrupted) image, OR the opposite extreme that it fails to turn on at all, there will be something visible, like popped capacitors or a bad solder joint.

Short of replacing the entire mainboard, TV repair is usually quite cost effective, costing less than $10 to replace discrete components, assuming you can solder.

The regular interval of 10 seconds then blackout suggests to me a bad solder joint, repetitively heating up, cooling down.

when i opened it, i didnt see any popped capacitors. that was the first thing i did according to so many youtube tutorials.
looks good right?

https://imgur.com/a/K8DUZG1

i havent the chance to measure the voltages yet...

 

[mindless1]

I don't see any popped caps, but for future reference, please always make pics of the entire PCB, not pieces and then rotated at different angles, unless there is a specific spot of interest where you do see something wrong.

If it's just the backlighting going out, trace the wiring from it to the PCB, and probe for voltage changes when it goes out every 10 seconds. If the voltage doesn't drop, you probably have a failed LED, or series resistor or fuse, or of course a solder joint. If the voltage does drop, follow the circuit on the PCB, backwards until it doesn't read anywhere near right, again changing every 10 seconds.

It goes without saying that this requires working with a live mains AC powered circuit, so do be careful, but at least it's not the thousands of volts a CCFL lit TV would have, and yet if it were, then odds are the cause would be a solder joint on the transformer or transistor for that.

 

[bruceb]

You need to remove the power board to look at the connections on the back side. Quite often, the poor solder joints will be where heavy leaded parts are installed. These boards are typically soldered by machine and if oxidation from the part leads is not removed before being installed, you get a cold sold joint. Heavy parts need more heat to solder properly.

 

[luv2liv]

I don't see any popped caps, but for future reference, please always make pics of the entire PCB, not pieces and then rotated at different angles, unless there is a specific spot of interest where you do see something wrong.

If it's just the backlighting going out, trace the wiring from it to the PCB, and probe for voltage changes when it goes out every 10 seconds. If the voltage doesn't drop, you probably have a failed LED, or series resistor or fuse, or of course a solder joint. If the voltage does drop, follow the circuit on the PCB, backwards until it doesn't read anywhere near right, again changing every 10 seconds.

It goes without saying that this requires working with a live mains AC powered circuit, so do be careful, but at least it's not the thousands of volts a CCFL lit TV would have, and yet if it were, then odds are the cause would be a solder joint on the transformer or transistor for that.

here are better photos. sorry for the terrible photos earlier. this time i zoom in on the area of interest with my notes in red

https://imgur.com/a/7GR77rF

what's strange is that i get 0 standby voltage. and yes, there are voltage drop when LEDs go blank.
i wonder if it's the rectifier. in standby it is solid 172v. but when TV is on, it stays solid at 112v.