Re: KDS LCD monitor, Sampo Inverter..

Franc Zabkar wrote:

On Wed, 04 Feb 2009 22:30:57 -0500, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@xxxxxxxxxxx> put finger to
keyboard and composed:


It appears I have a failing inverter with a KDS 17" monitor.
this is a dual unit Sampo QPWBGL9151DG
http://www.lcdpart.com/Products/qpwbgl9151dg.html


I found a pin out on the net and states that pin's
1,2 = 12V, it has that, pin's 3 is a On/Off, it's at
~ 4.1 volts via a resistor from the processor board coming from
a 5 volt source. Pin 4 is a dimmer control, it's at 3.35 volts,
5 is ground/common..

With that, I assume the inverter board should be operating and
generating some voltage to the CCL lamps?

Is my assumption correct? If So, I guess I need to repair the
inverter ?


It could be that the ON signal is active low, in which case shorting
it to ground should turn on the inverter. To find out for certain, you
may find an application circuit in the datasheet for the main IC (top
centre in your photo). It may also be helpful to view the data for the
8-pin ICs below each of the coils.

The usual culprits in inverters appear to be electrolytic capacitors,
so I'd change those first. I'd also reflow the solder joints at the
transformers and coils.

- Franc Zabkar
Ok, i've already tried pulling that On/off signal to ground.
It does nothing, Normally standard markings of on/off is the same
order as +/-, since I'm getting + to that pin from the processor board
via a resistor from a 5 volt supply, I guess that thought is out the
door, but like I said, I did pull it low with out success.

There is 1 electrolytic on that board that seems to be related to both
inverters . I will lift the board from the chassis and inspect closer..

thanks.

http://webpages.charter.net/jamie_5";

.

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