SMPS Clicking...

I have seen similar issues on Samsung plasmas resulting from bad solder connections at some switching transistors near the middle of the board. The eyelets are too small and need to be scraped a bit to enlarge them before resoldering. The board does look similar to yours. Maybe you'll get lucky. If not solder connections in there somewhere, failing capacitors would be the likely culprit, although this problem has been much more common on LCD sets. Plasmas I've seen don't seem to use the really cheap caps.

Mark Z.

Thanks you suggested that before.. I will get a closer look at the transistors and check out those eyelits.. I havent doent that yet, and probably would have forgot had you not replied.

About the ticking.. It doesn't stop even with the power removed. It is almost if something is expanding and contracting, but makes the sound equilivant of a relay?!

The really strange part is it doesn't seem to come from one consistant place.. :(

Power removed or TV turned off? If it continues long after the set is turned off (but still connected to AC power) it is something in the standby power section of the main power supply.

If it continues for hours after the set is unplugged, it's probably a cricket.

PlainBill

I would change the main 400v capacitor clicks means this capacitor is almost dry ... regards,

Its got to stop sometime after its been unplugged. I do not think there are any relays in todays plasma power boards, so the ticking is likely coming from a transformer. Its a ' special effect ' that happens when the power supply is loaded down somewhere, usually on one of the main DC outputs. The overload condition triggers an imbalance in the feedback circuirty, and the power supply cannot sustain itself with this condition present. You may want to check the temperature of the big heat sinks on the X-sus board at the peak of the problem, could be they are very hot.

No its not hours, but at least 3 or 4 minutes.. Sounds like a realy clicking sometimes.. Other times not so loud.. Makes me think of expanding and contracting metal, although I cant see how that is possible given the low tempatures.

Hope it isn't the PDP. I've read horror stories about those expanding and contracting (they do get VERY hot), and finally cracking.

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In the UK there is some bug that clicks , regular clicks when active, but not continuously, comes and goes at random. If , when it is in tapping mood, you tap near wherever it is hiding, it stops abrubtly, presumably thinking its found a mate. Not death-watch beatle as not in timber

snipped-for-privacy@yawho.com wrote in news: snipped-for-privacy@4ax.com:

the ticking could be the PS current limiting and restarting:I've heard that in lots of TEKTRONIX switchers. It should only last as long as the charge in the mains filter caps.

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mood,

perhaps the insect that does this is called a tick

Well thats good advice, but it appears that they are good. I checked them with my esr meter out of circuit and they both have an esr of 0.12 ohms.

Agreed. The mains filter cap can easily hold a charge for 5 minutes if there is no load. I have observed an SMPS clicking as it trys to start, but fails due to a bad Vcc cap (10-47 µF). I am unable to comprehend a circumstance that would allow that to be the source of the noise on a functional power supply.

PlainBill

snipped-for-privacy@yawho.com wrote in news: snipped-for-privacy@4ax.com:

some cap or caps(electrolytics,usually) may be marginal,and adding up to right near the current limit point,or maybe a resistor divider that sets the reference for that limit has changed value. any condition that draws extra power from the supply causes it to go into current limit.

it sure sounds like a cap problem.

Thanks, Im going to give this another once over again and check any caps possibly overlooked. I reflowed a lot of marginal looking soler joints. But this being PBF construction they all look marginal.. Have been removing the bad solder and replacing with standard solder.

Someone else suggested that the problem may lay in the x or y sus boards. The y sus board's heat sink gets much hotter than the x sus even though the contrustion between the two is very similar. It is hot enough that it is uncomfortable to hold your hand on.

So maybe the noise I hear is the PSU current limiting and the cause is the y sus board sucking too much juce...

It had some very small capacitors which were possibly bad. I forget their value, but were in the 6 ohm range when tested with my esr meter, althouh unphased by freezer spray.

I think you hit the problem dead on. The Y sus board is getting quite hot but the x sus isnt. Any idea what would cause the board to consume more wattage and therefore get hot?

The components being heat-sinked are probably drawing too much power, either because they are about to quit and go total short condition, or whatever they are supplying drive power to is causing them to draw too much power. I have seen X-sus main output components with the large heat sinks short out, but so far never the Y-sys. A lot of the time the components being heat sinked are proprietary, and seem to have these heat sinks sonicly welded to them permanently. The only way to do a repair is to do a board swap with a known good board. Good luck.

Hmm.. I will have to have a look at the transistors and see if they are propritary. They are attached by bolts and this board is designed to be reparied judging by the detail of the service manual.

This tv was quite expensive when new and seems as if built in a different era.. Say 25 years ago back when thigs were buit with repair in mind. The SM actually lists individual components and how to troubleshoot them.