Sony KDL-32S2010 inverter panel

[Contrast John]

Hi All
Hope this information may be of help to anyone repairing one of these inverter panels (type KPC2294V).
The fault symptom displayed by this set was-Screen darker at the top and a flickering of the backlight brightness. Surprisingly the set was still operational.
Fuse C03 on the inverter panel had blown cutting off the supply to 4 of the 8 transformers. By disconnecting the various links in the supply feeds I was able to establish that Q601 and Q602 were both short circuit. These 8 pin sm devices type RSS065 N06 are in fact N type Mosfets and use only 3 connections. Attempts to replace with power FETs available in the workshop were unsuccessful as the FETs ran too hot. Managing to obtain a datasheet for the RSS065 on the web, I was able to find a FET with similar spec (rise and fall times) and reduce the heat. The devices used were IRF740 readily available at around £1 each. These FETs are in non-isolated packages so care was needed in mounting them under the board. However there is an insulating sheet between board and chassis and just to be safe another was added. After monitoring the temperature of the FETs over several days the set was reassembled and has now been in regular use for a month. Has anyone else tried this type of modification before on this or similar inverter panels, and what devices work best in this position?

Regards
John.

[Turnip]

Hi John - congratulations,

   This smacks of good old fashined telly mending. Haven't done it myself, apart from bipolars with monitors where the tuning cap went phut. More power to your Weller.

  Suspect you are not one of these modern chaps where panel changing is the only option.

  Do you do anything useful with those Chinese power supplies ?

  Rather impressed - Chris.

[Contrast John]

Hi Chris
Thanks for your reply. It was quite rewarding to find a cheap solution to an expensive repair although rather a lot of time was spent on research. Times have certainly changed since I entered this trade in the 1980s and repairs were generally to component level. Nowadays the lack of service information or spares make economical repairs difficult to achieve.
Not seen much of those chinese power boards yet but if I manage a repair on one will post the details.
Regards
John

[Turnip]

Hi again John,

   Have to admit that I started the job as an enthusiastic boy in the 50's when known names actually made things, gave free manuals and held servicing courses with beer and sandwiches just to prove it.

   Todays stuff, although a bit short on - pretty well everything really, is a challenge, but as no-one really expects us to mend them anyway - we have lots of bits for when something similar turns up.

   Well it's different, but there's a still pound or three to be made out there, somewhere - Chris.

[Contrast John]

Hi Chris
Think it's our engineers enthusiasm that keeps us going.
Agree with your comments about parts - just wish that I could find two panels that are the same!

John.