Atlas 37AV500U popping sound

[tibimakai]

I have picked up this Toshiba TV(sorry about the Atlas, somebody could change the name please?) and the previous owner claimed that not always would start up.
I haven't noticed this issue yet, but sometimes, there is a loud popping sound coming through the speakers. If I disconnect the speakers I can't hear the popping sound anymore.
Picture is great, inverter boards are the 811s. With the inverters disconnected it still pops.
Capacitors are the KY type, except on the inverters, which are Rubycons.
I should start by replacing these capacitors on the power supply?
Any help would be appreciated.

[tom66]

Re: Atlas 37AV500U popping sound

I would look around the amplifier area... specifically the nearby decoupling capacitors.

Does it happen on louder sounds? Or when silent? Independent of audio level?

I know on LGs this is caused by a bad cap for the audio power supply (usually 17 - 19V) - and this is likely to be indicative of other bad caps. Chemicon KYs are very good, but watch out for Chemicon KZE which are prone to bulging. Rubycon are very good, too.

Tracing a fault like this will likely require an oscilloscope, unfortunately.

Pictures help, too...

[tibimakai]

Re: Atlas 37AV500U popping sound

I'm not using any signal, just the TV by itself.
I will take some pictures, you are interested in the main board?

[retiredcaps]

Re: Atlas 37AV500U popping sound

Chemicon KYs are very good, but watch out for Chemicon KZE which are prone to bulging.

KY and KZE are good. KZG is the problematic series and will die under the smallest amount of heat. I have a few dead motherboards and KZGs die near the CPU socket.

https://www.badcaps.net/forum/showthread.php?t=2280

Even sitting in storage they bloat.

https://www.badcaps.net/forum/showthread.php?t=19441

[tom66]

Re: Atlas 37AV500U popping sound

I'm not using any signal, just the TV by itself.
I will take some pictures, you are interested in the main board?

Main board and power supply.

[tibimakai]

Re: Atlas 37AV500U popping sound

Here are the requested pictures:

[tibimakai]

Re: Atlas 37AV500U popping sound

So which capacitors would be those?
Those four capacitors on that small pcb looks like they could be for the audio amplifier. Wires come from main board where the amp is located and from the small board the wires run all the way to both speakers.

[budm]

Re: Atlas 37AV500U popping sound

This TV uses Class D power ampliers (two amp in one chip), Do you hear poping sound if you use the audio line out? If you do not, then the problem is in the power amp, or power supply problem as mention by others, if you do hear the popping in the Audio line level output (Red and White RCA audio line out) then the problem is in the preamp section.

[tibimakai]

Re: Atlas 37AV500U popping sound

I haven't plugged in anything in this TV, just by itself with no in/output cables pops.

[budm]

Re: Atlas 37AV500U popping sound

Since both channels are popping, then Power supply is common to both channels, then as suggested by others, check the power supply caps in both the power supply module and in the main board.

[tibimakai]

Re: Atlas 37AV500U popping sound

the electrolytic ones?

[budm]

Re: Atlas 37AV500U popping sound

More likely, but can be MLCC also

[tibimakai]

Re: Atlas 37AV500U popping sound

I'm having issues ordering the blue capacitors from the power supply. What type of capacitors are they?
On some of them it's not specified the voltage. (104 and 105)
There is a preferred brand? They should have a specific temperature range?
For example 22J 1KV what size it is?

[tom66]

Re: Atlas 37AV500U popping sound

These are class-Y safety capacitors - no need to replace them.

Retired, sorry for the confusion over the caps. Indeed, I look at one of my motherboards and see a bloating KZG that I need to get around to fix.

[budm]

Re: Atlas 37AV500U popping sound

22J 1KV = 22pf 5% 1000V. If it is X/Y type, then it should be printed right on the body of the cap. Where is this cap 22J located?

[tibimakai]

Re: Atlas 37AV500U popping sound

sorry about the late reply, but I haven't had time to work on it.
it's next to the biggest transformer on the primary side(first picture, above the transformer).
So today I have replaced all the electrolytic capacitors on the power supply and on the main board.
The popping is still there. It began doing the popping much later, about 7 restarts, previously after the second restart it was popping.
So I guess the next step is to replace the blue capacitors. These are ceramic capacitors? Could somebody show me one on digikey? It matters the brand, type?

[tom66]

Re: Atlas 37AV500U popping sound

sorry about the late reply, but I haven't had time to work on it.
it's next to the biggest transformer on the primary side(first picture, above the transformer).
So today I have replaced all the electrolytic capacitors on the power supply and on the main board.
The popping is still there. It began doing the popping much later, about 7 restarts, previously after the second restart it was popping.
So I guess the next step is to replace the blue capacitors. These are ceramic capacitors? Could somebody show me one on digikey? It matters the brand, type?

Where is the cap located?

[selldoor]

Re: Atlas 37AV500U popping sound

i"t's next to the biggest transformer on the primary side(first picture, above the transformer)."

I can barely make it out - this picture is useless!

[tibimakai]

Re: Atlas 37AV500U popping sound

I agree about the quality of the pictures, they were taken with my phone. Sorry about that. I work in my garage and I don't have natural light in there.
I will take some new pictures and more of them in a short while.

[tibimakai]

Re: Atlas 37AV500U popping sound

here are the pictures: