68uf 400v Capacitor making a clicking sound....Advice please

[katana]

Hi,
my JVC home cinema DVD player, suddenly died . Suspected the power board and replaced a few 'suspect ' componants. Switched on, and was working fine......switched off (10 minutes later) and now its dead again (no standby light etc) After removing the top casing and plugging in ...I could hear a faint clicking sound....coming from the main, low profile 400V 68uf cap !!! I want to replace it.
I assumed that being a power supply board all the caps would be low ESR ...but cannot find a replacement cap with the right dimensions/ rating that has a low ESR.

My questions are, does the clicking sound mean the cap is bad (internal arcing ?) ? Does the replacement cap need to have a low ESR ?

I'd appreciate any advice, thank you

Regards David

[retiredcaps]

Originally Posted by katana

After removing the top casing and plugging in ...I could hear a faint clicking sound....coming from the main, low profile 400V 68uf cap !!! I want to replace it.

My questions are, does the clicking sound mean the cap is bad (internal arcing ?) ? Does the replacement cap need to have a low ESR ?

Please post a clear focused picture of your board using the manage attachments button (do not post inline).

On most computer LCD power boards, the clicking indicates that the SMPS controller is trying to start. Next to the SMPS controller is a small startup/run cap that is usually 22uF 50V or in that range. These little caps can go bad without showing signs of bloating.

In the LCD world, that cap is responsible for the SMPS not being able to start in the majority of the cases. Additionally, it is rare for the big cap, but not never, to fail.

If the big cap is the culprit in this case, it does not have to be a low ESR cap.

Anyway, the picture will help a lot.

[katana]

Hi Retiredcaps,
thank you for replying . Here are a few pictures of the board. The IC near to the large cap has been replaced (afterwards the player 'worked' for 10 minutes, but after turning the power off ....the player refused to work. The IC was tested afterwards and was found to be OK). All the resistors and diodes in and around the large cap seem to checkout OK.

The top of the large cap looks to be very slightly distorted, photo's do not show this. The replaced IC is a str g6651 (flyback switching regulator)

Kind Regards David.

.

[Pyr0Beast]

I would replace that 400V cap.

[retiredcaps]

Originally Posted by Pyr0Beast

I would replace that 400V cap.

Might as well order a replacement for C914 as well. That is the little cap that I think is part of the startup.

[Toasty]

Replace C914. Panasonic FM or better. Mains cap is fine.

[Pyr0Beast]

Originally Posted by retiredcaps

Might as well order a replacement for C914 as well. That is the little cap that I think is part of the startup.

Oh yeah. Failed to see that one but I was looking for it. Defenitely replace it is probably the cause of fault and 400V cap could be just fine.

[katana]

Thank you all for taking the time to reply, greatly appreciated.
Already ordered a new 68uf 400v cap but got a 105 degrees temp rating, instead of the standard 85. Will get a replacement for C914 and fit it first....to see if it cures the problem (before replacing main cap) Then if this fails to work I'll then replace the main cap. This way I'll know which caused the fault ....and, if the main cap, perhaps the clicking may help diagnose a faulty one (for others on the forum) ??

Will let you know how I get on.....thanks again

Kind Regards David

[retiredcaps]

Originally Posted by katana

Will get a replacement for C914 and fit it first....to see if it cures the problem (before replacing main cap) Then if this fails to work I'll then replace the main cap. This way I'll know which caused the fault

That would be great. Many of us want to know what is root cause.

[Pyr0Beast]

Bootstrap caps often fail.

[Agent24]

Tick-tick-tick - Too little or no load. In a TV or monitor using an SMPS, this is likely due to a lack of horizontal drive or a blown fuse or fusable resistor in the horizontal deflection system. The power supply is in a repeating cycle of starting up, being unable to limit the regulated voltage to a safe value, and shutting down. Attempting to power up an SMPS without an adequate dummy load may result in these symptoms.

From: http://www.repairfaq.org/sam/smpsfaq.htm#smpsstsm


I have also read about internally arcing diodes making funny noises. If the new capacitors don't solve your problem I'd look at the diodes in that area of board which has obviously had the most heat.

[Pyr0Beast]

Originally Posted by Agent24

From: http://www.repairfaq.org/sam/smpsfaq.htm#smpsstsm


I have also read about internally arcing diodes making funny noises. If the new capacitors don't solve your problem I'd look at the diodes in that area of board which has obviously had the most heat.

Had a lightning strike damaged diode. Nothing could be noticed until you applied power.

Smoked like hell. Package just fell apart

[kocoman]

Does anyone have update for this?

[selldoor]

Welcome to the forum

Originally Posted by kocoman

Does anyone have update for this?

It quite unlikely - the post is over a year old!!

If you have a similar problem it is probably better to start a new thread
Please update your profile with Country and Mains Voltage

We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed
http://www.badcaps.net/forum/attachm...1&d=1290283049

http://www.badcaps.net/forum/attachm...7&d=1280167246

It will be useful if you can say what the supposed fault was and a bit about yourself - skills tools etc.