Sony DAV-SA30 Power Supply

Apr 26, 2006 3 Replies
R

Hello Guys,



I have a Sony DAV-SA30 DVD surround system. It has been making a ticking noise through the speakers so I thought I'd have a look inside..



I found that the power supply module, 1-687-086-15, is supplying



34.7volts on it's 27v output.

The 27v supply is high wattage to the amplifier card, it goes at follows:


  • from rectifier goes to the pin 1 of Q904, a 3 pin chip. Pin 2 of Q904 goes to the connector that supplies +27v to the amp. Pin 3 has a thin PCB trace going to various surface mount components presumably to control the voltage level.

I am trying to locate the fault but cannot identify Q904, it is labeled PK K1189 33. What do you think is my best bet for repair? Maybe a new voltage regulator bypassing this Q904?



Any ideas gratefully received! Kris.


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F

On Wed, 26 Apr 2006 21:01:22 +0200, real_pixie put finger to keyboard and composed:

2SK1189 MOSFET?

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Check the drive to the gate of the MOSFET. Check for a D-S short circuit.

- Franc Zabkar

Please remove one 'i' from my address when replying by email.
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R

Thanks Franc,

I have removed the MOSFET from the board and tested the resistance between pins, D-S is approx 1 ohm, which I understand would be correct for a MOSFET, the gate pin has only 10 ohm resistance to both the D and S. I think this may be the problem, I believe MOSFET G-D/S resistance should be very high.

I'll get hold of a new MOSFET and give it a try. Do you think the 34v going back through the gate will have damaged the drive circuitry?

Thanks for your help so far, Kris.

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On Thu, 27 Apr 2006 19:24:43 +0200, real_pixie put finger to keyboard and composed:

There should not be a D-S short in your MOSFET. Replace it and verify that any other device attached to its gate has not been damaged.

- Franc Zabkar

Please remove one 'i' from my address when replying by email.
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