HanNspree HSG1066 repair

[budm]

Symptom:No inidcator, no 5v or 16V
Cuases: Blow fusible resistor R808 0.2 Ohm in the Primary side for B+ feeding the SMPS IC due to shorted out snubber cap C809 100pF 1000V (connected between the Source and Drain of the power MOSFET).

[budm]

Re: HanNspree HSG1066 repair

More pictures.

[tom66]

Re: HanNspree HSG1066 repair

Nice fix. Strange to see disc ceramic fail, they tend to be quite reliable. Perhaps the design exposes it to over 1kV on some of the switching points, or the part is not rated for 1kV continuously.

[ben7]

Re: HanNspree HSG1066 repair

Nice fix. Strange to see disc ceramic fail, they tend to be quite reliable. Perhaps the design exposes it to over 1kV on some of the switching points, or the part is not rated for 1kV continuously.

Indeed that is a bit worrying, the highest MOSFET D-S breakdown voltage I can recall is 900v.

[tom66]

Re: HanNspree HSG1066 repair

MOSFETs are commercially available up to 3kV breakdown voltages, but you will not see it in consumer gear. I have seen 900V rated FET in flyback converter once.