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Crown I.T 4000 Itech series Power board fault

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We have a Crown I.T 4000 Itech series with a faulty board, the board is marked:

on the bottom side

PWB 136542-9

and on the top side

PWA 137095-6

PWA 137098-8

PWA 137101-9

The resitor R12 is blown but the fuse on the board is intact and are signs of a prevoius repair, the Bridge rectifer looks like it was replaced and also a small transistor.

Has anyone got a schematic for this board, also any info on the test points.

Also, should E1 Led flash during normal operation.

Would the board work in normal use if the ribbon connector is detached. Ie would that led be on or flashing.








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Hello Andy,

The problematic board is called the EMI board. This board includes a bootstrap psu. The green led should be solid, not blinking. So, it may be possible that the psu may be faulty.

The SMPS module has two main cables supports : the main output rails voltage connection and the LV signals (ribbon cable) connection. To test the smps, you can remove the main output rails harness (blue, red and black wires). Please discharge the high voltage rails before manipulating the harness! If you have an output failure the smps will not fire if the harness is connected.

The other [ribbon] cable needs to be installed or secured to the main board. The display cable (and power up lines) should be connected to the audio card, and the audio card's 50p connector to the main board (because the front power switch uses some lines in the ribbon cable).

I believe the EMI board is still available from Crown.


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Thanks for that Joust, its cleared some parts up.

I was busy so I will take another look at it this week.

Thanks for replying

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soy de venezuela tengo unos crown itech4000 y uno de eyos se me apaga un canal desde ves en cuando pero lo golpeo y arranca el canal y de repente se me apago ambos canales y se me apago la pantalla y quedo en modo de fault ambos canales y no arranco mas sino que quedo en modo de fault que puedo aser en este caso ayuda x favor

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