SMPS Clicking...
Michael Kennedy
I have a SMPS in Plsama tv which upon powering up starts clicking... It
seems to do it as it warms up or the load changes on the psu (screen going
dark or getting light)
As far as I can tell it isnt any relay doing this, even though It sounds
like a relay.
Ticking alone I could live with, although a bit annoying but the PSU also
occasionally shuts down when cold. I am not 100% sure what is clicking.. The
clicking noise seems to be coming from different locations at dfferent
times, even possibly the X or Y sus boards.
I have sprayed the whole thing down with freeze spray to no avail... It is
built with PBF solder, so I guess bad solder joints are likely issue also.
I have changed the obvious capacitors near heat sources excpet the two large
400v 250uf filter caps.. Removed and checked the filter caps and they
checked good on my ESR meter.
Any Idea what would be clikcing? Here is the board layout
<https://sites.google.com/site/chibamikey/PSU.JPG>
Mark Zacharias
news:_PidnbvlitJd_TDR...@giganews.com...
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.
Michael Kennedy
"Mark Zacharias" <mark_za...@sbcglobal.net> wrote in message
news:4cadb755$0$1752$c3e8da3$9f40...@news.astraweb.com...
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.. :(
Plain...@yawho.com
wrote:
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
jeanyves
I would change the main 400v capacitor
clicks means this capacitor is almost dry ...
regards,
--
-
Jean-Yves
circuit
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.
Michael Kennedy
<Plain...@yawho.com> wrote in message
news:5f0sa6dr1m0falp5k...@4ax.com...
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.
Brenda Ann
"Michael Kennedy" <mike@com> wrote in message
news:xbidnZTf8NMI8zPR...@giganews.com...
Hope it isn't the PDP. I've read horror stories about those expanding and
contracting (they do get VERY hot), and finally cracking.
>
N_Cook
> >
> 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
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
Jim Yanik
news:5f0sa6dr1m0falp5k...@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.
--
Jim Yanik
jyanik
at
localnet
dot com
N_Cook
news:i8mi0f$3p1$1...@news.eternal-september.org...
perhaps the insect that does this is called a tick
Michael Kennedy
"jeanyves" <no-pub-fo...@free.fr> wrote in message
news:4cae249a$0$30015$426a...@news.free.fr...
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.
Plain...@yawho.com
wrote:
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
Jim Yanik
news:eetua616008tuaflq...@4ax.com:
> start, but fails due to a bad Vcc cap (10-47 湩). I am unable to
> comprehend a circumstance that would allow that to be the source of
> the noise on a functional power supply.
>
> PlainBill
>
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.
Michael Kennedy
"Jim Yanik" <jya...@abuse.gov> wrote in message
news:Xns9E0BBC8EA283A...@216.168.3.44...
>> comprehend a circumstance that would allow that to be the source of
>> the noise on a functional power supply.
>>
>> PlainBill
>>
>
> 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.
>
> --
> Jim Yanik
> jyanik
> at
> localnet
> dot com
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.
Michael Kennedy
"circuit" <cir...@123456.tv> wrote in message
news:i8lpju$q0l$1...@speranza.aioe.org...
> 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.
>
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?
circuit
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.
Michael Kennedy
>
>> 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.