Insignia ns-p501q-10a Cycling on and off

[ludomonster]

I have an Insignia ns-p501q-10a 50 inch plasma that began cycling on and off last night.

I am considering having someone repair it, but if I can troubleshoot the problem on my own, I might as well do it myself.

I took the back panel off to try to see if cleaning the fan would help it. It didn't. There is no fan to clean.

I did see a whisker that may have shorted out a capacitor; however, clearing out that dust did not solve the problem. I didn't check the fuse on the power supply. Right now, I don't suspect the fuse.

When I plug the TV in, it automatically begins to cycle. I can hear one solid relay firing followed by a few taps. Shortly after that, the relay fires again, turning the TV off.

During this time, the power LED on the from of the TV turns solid, then blinks. I don't know if this is a diagnostic code or if it's just a symptom.

I didn't see or smell any smoke when this started to happen. Also, the capacitors didn't appear severely deformed. I will have to take a look at them later.

What can I do to ensure that the PS is faulty? If a bad capacitor is the culprit, is it worth replacing vs the whole board? I haven't soldered in 15 years and never really was great at it.

[ludomonster]

Re: Insignia ns-p501q-10a Cycling on and off

Update: I found the manual for the TV and I'm going to use the troublshooting procedure relating to the relay cycling issue.

[SuperSkippy]

Re: Insignia ns-p501q-10a Cycling on and off

When you say it cycles on and off, do you ever get any picture? Or does it just flash the light a lot?

[ludomonster]

Re: Insignia ns-p501q-10a Cycling on and off

When you say it cycles on and off, do you ever get any picture? Or does it just flash the light a lot?

There's no picture. The power indicator LED flashes. I unplugged the power to the Y board and the power cycling and flashing LED symptoms went away, leading me to supect that it's the Y board. The Vs voltage to the board is 209V. The boilerplate states that it should be 210V. I'm assuming that it's within tolerance.

I don't have an oscilloscope, so I can't do any waveform analysis.

The board is running at just under $200 to replace it. A few sites list the board for less, but are out of stock. Given that this TV is a few years old, I'm assuming that these sites won't be restocking this part. I also looked for the part for the equivalent Samsung model TV.

[tom66]

Re: Insignia ns-p501q-10a Cycling on and off

209V is fine for Vsus, typically tolerance is +/-1V.
The fault on these often turns out to be four transistors on the lowest heatsink (looking at the board as installed in the set.)

[ludomonster]

Re: Insignia ns-p501q-10a Cycling on and off

209V is fine for Vsus, typically tolerance is +/-1V.
The fault on these often turns out to be four transistors on the lowest heatsink (looking at the board as installed in the set.)

Is there anything I can do to confirm it?

[tom66]

Re: Insignia ns-p501q-10a Cycling on and off

You can check between each pin (1-2, 2-3, 3-1) for short circuits on the diode test. A result of less than 200 is suspicious. Once a suspicious device is located, it needs to be removed and tested out of circuit.

[ludomonster]

Re: Insignia ns-p501q-10a Cycling on and off

OK, thanks.

[ludomonster]

Re: Insignia ns-p501q-10a Cycling on and off

I found two MOSFETs attached to that heatsink that scored 0 on the diode test across the 3 - 1. I won't be able to remove them for a few days.

[tom66]

Re: Insignia ns-p501q-10a Cycling on and off

A quick test is to chop at least two of the leads off close to the PCB to isolate them, then you can see if the devices have any shorts. Also you need to get the part number of the device because some devices like diodes have a connection between the two outer pins.

[CoppellTVRepair]

Responding here, albiet with significant delay, for hopefully the benefit of those still in need.


We're component level service center for TV boards and since there's a particular shortage on market for particular board for The NS-P501Q-10A I am allowing myself to plug in here.

The two most common failures in NS-P501Q-10A are the X-Main LJ92-01688A and the Y-Main LJ92-01689A boards.


They fail independently from each other, just because of wearing out (yes, electronics wear out, due to thermal cycles of expansion and contraction of semiconductor junctions during periods of activity and inactivity).


Both boards also have other identification numbers that we are not listing here.


X-Main is the one that sits on the RIGHT side of the TV when looking from the back while Y-Main sits on the left and is attached to a long board, called a buffer board.


X-Main tends to fail more than the Y-Main, but given enough time both eventually will fail; as of this writing it's harder to find and more expensive.


We offer repair service, exchange service (when boards are available) and DIY repair kits for both boards; repair services mean we test boards in live TV.


Just a note for those wlling to belive: this is one of the many cases when a properly rebuilt board is much better than a used board. If you believe that electronics age (which is easy to do if you see how many people complain from failures) then it should be easy to see why a properly done repair is better than buying a used board that still functions: all components that tend to wear out should be replaced with new ones while a used board will only have so many more thermal cycles before it fails again.


Lastly, it is also important to point out NS-P501q-10a may have more than one version; before making any orders or assumptions open up your TV and make sure it uses the boards the according listings are for!


So here are a few links in case the site allows me to post them:


X-Main board repair service:

****************************


Y-Main board repair service:

**************


Hope this helps!

[DXseekerMO]

Re: Insignia ns-p501q-10a Cycling on and off

Hey there CoppellTVRepair, I see your repair videos on YouTube and I've learned a lot from them. Thanks for sharing your knowledge and I appreciate it!