Testing the Inverter on Samsung PSU BN44-00150A

[nogger]

Hi all, looking for tips on how to test the on board inverter on power supplies for the larger (50") Samsung power supplies. I'm getting more & more of these in lately , mainly the caps/relay clicking issue but now had a few where there's possible inverter problems i.e the complaint is Sound is ok but no display .

Obviously i can't have an inverter board/panel in stock for every different PSU that comes in so i need a way of testing just the inverter circuitry built into the PSU. I understand that the PSU connects to Inverter balance boards that distribute the high voltage equally along to the tubes but i need to be able to just check the onboard circuitry. also, although i have the service manual for the receiver (LE52M87BDX) the circuit diagrams do not show any of the inverter circuitry , just the normal standby & DC outputs. Anyone know:

(a) where there is a circuit showing the inverter circuitry ona 50-52" set

(B), Whats the output voltage from the transformer that connects to the inverter balance boards.

(c) should i be able to connect normal CCFL inverter tubes directly to this transformer output or do i need these balance boards. I dont want to overdrive the onboard inverter by caoonecting a couple of tunes up directly. I know the output will be over 1KV so need a reliable way of safely testing without the inverter circuit shutting off.


Thanks in advance

Graham

[tom66]

Re: Testing the Inverter on Samsung PSU BN44-00150A

A. Here's one for the 40" models: It should give you a start.

B. The output voltage is around 3-4kV with an ~8kV starting pulse.

C. No if you connect ordinary tubes they will melt/burn/smoke. Ordinary tubes ignite with around 1-2kV, then run at 600-1000V.

[nogger]

Re: Testing the Inverter on Samsung PSU BN44-00150A

Tom66 , many thanks for the drawing .

I actually have a cracked samsung panel lying around but it doesn't have the inverter board with it. Taking your point on board of not using ordinary CCFL tubes from a small monitor, if i find a way of connecting a couple of these tubes to the PSU inverter output will that work do you think or does the balance board reduce the 3-4kv downwards.
Graham

[tom66]

Re: Testing the Inverter on Samsung PSU BN44-00150A

The balance board does the voltage dropping; I'm not at all sure how, but it's also involved in making sure each bulb gets the same current (hence balancing...)

[budm]

Re: Testing the Inverter on Samsung PSU BN44-00150A

IF you look at the LCD panel spec, it should give you the Voltage/current requirement of the T-CON, LAMPS, etc.

[nogger]

Re: Testing the Inverter on Samsung PSU BN44-00150A

Thatsagood idea budm, why didnt i think of that :-)

Graham