Anyone got a service manual for a Samsung le32b652t4 set?

Plugged in a network cable today from a 803.af poe switch and it started smoking.

Looked on the board and several SMD transistors near the network socket have fried.

I can't see any isolating transformers!

Reply to
dennis
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they look like ...SMD transistors..

Reply to
The Natural Philosopher

Not with three legs they don't.

Reply to
dennis

Just kidding. Usually built into the actual socket these days.

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Reply to
The Natural Philosopher

En el artículo , The Natural Philosopher escribió:

Often left out (socket without isolating transformers fitted) to save money. The first batch of Raspberry Pis had to be recalled and reworked for this reason.

Reply to
Mike Tomlinson

Come on now, nobody produces a live chassis item with connectors that can be used like that. the problem has to be something in the device. What has it done to the other end, whatever was plugged in? Brian

Reply to
Brian-Gaff

Yes, remember the production problem with the early Raspberry Pis.

Reply to
Bob Eager

Nothing as it is designed properly with isolation as required.

For all I know the TV has isolation but it obviously failed as there should be no way to do damage plugging in a poe switch rather than a non poe switch.

I emailed Samsung and they have asked me to contact their service centre so I will do that Monday and see what they have to say.

The damn thing still works as a TV (no HD tuner) but the hdmi and ethernet no longer work which makes it pretty useless to me.

Reply to
dennis

I don't think there has been a live chassis TV etc produced for decades. That practice really ended with all transistor designs - and of course the ability to connect an external device like the first VCRs, other than via the aerial socket.

Reply to
Dave Plowman (News)

In which case they /should/ be built in to the metal can of the socket ... unless someone slipped up and specced the type of socket that expects the magnetics to be housed separately on the PCB ...

Reply to
Andy Burns

'Often'? Just curious because I haven't seen this before. AIUI the transformer is used to bias the NIC side and filter out common mode signals so you can't simply omit it, though perhaps something could be faked up with Rs and Cs.

The Pi issue was because the manufacturer was being dumb and substituted a non-magnetics RJ45 for an integrated magnetics one - that's just a stupid procurement decision, I don't imagine the Pi ethernet actually worked in that state.

Magnetic-less ethernet does exist, in standards like 1000Base-KX and

10GBase-KR where it is a backplane interconnect. You need a different PHY for that, though.

I wouldn't be surprised if some unfortunate device manufacturer grounded unused pins on their RJ45 'to reduce noise' - which causes fireworks when PoE is attached.

Theo

Reply to
Theo Markettos

They may be transient voltage suppressors (which absorb voltage spikes - up to a point). They can come in three legged SMD packages that you can't tell apart from transistors.

Does it still work after the smoke? It isn't strictly necessary to have TVSes, though it probably won't pass EMC/noise immunity and be more susceptible to further damage from spikes.

Can you take a picture?

Theo

Reply to
Theo Markettos

That was a mistake, not a design choice.

Reply to
Andrew Gabriel

En el artículo , Andrew Gabriel escribió:

I know, I didn't imply otherwise. They recalled them and fitted the correct part.

Reply to
Mike Tomlinson

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