* Sony shares tumble more than 7 pct on Weds

* Hirai may announce big job cuts - media

* Japan's electronics sector struggling vs competition, yen

* Hirai took over as CEO on April 1

By Tim Kelly

TOKYO, April 12 (Reuters) - Kazuo Hirai's brief honeymoon as Sony Corp's new chief has ended abruptly as the struggling electronics giant doubled its annual loss forecast, sending its shares tumbling.

On Thursday he will try to convince investors he has a strategy to fix Sony and its ailing TV unit, and turn around a brand that has been trampled on by consumer gadget leaders Apple Inc and South Korea's Samsung Electronics.

Hirai, who succeeded Howard Stringer as CEO this month, will lay out a detailed plan he hopes will revive the company hobbled by a television business that has racked up $10 billion in cumulative losses in eight years, battered by weak demand, fierce competition and a stronger yen that makes exports less competitive.

At stake is not only the viability of Japan's best known brand, but also the future of Japan's once-dominant TV industry.

"Japan's consumer electronics industry is facing defeat," said Fujio Ando, senior managing director at Chibagin Asset Management.

Sony, Sharp Corp and Panasonic Corp, Japan's three biggest TV makers, expect to report a combined loss for the year just ended of $21 billion - more than Sony's entire market value.

Hirai, a 26-year Sony veteran, has vowed to take "painful steps" and insisted he won't shy away from weeding out poorly performing businesses or making cuts to bolster profitability. He is likely to announce a third wave of job cuts, adding to the two rounds of layoffs Stringer made in his six-year tenure.

The axing of another 10,000 jobs, according to local media reports, comes as Sony expects to announce in May a record $6.4 billion loss for the year to end-March. Sony is targeting a return to operating profit in the current business year - of 180 billion yen ($2.22 billion).

"We believe the revival of Sony entirely depends on the improvement of profitability in its core manufacturing business," Masashi Oda, general manager of the equity investment department at Sumitomo Mitsui Trust Bank, Sony's largest investor, said in an e-mailed reply to a Reuters query.

"At the moment, Sony would not be sustainable without restructuring, and we recognise Sony is heading in the right direction with its efforts."

JP Morgan analyst Yoshiharu Izumi estimates Sony would need to find an additional 80 billion yen in cost savings or higher earnings to meet its profit target for this year. "We think management is assuming additional restructuring benefits as well as extra revenue growth," he wrote in a client note.

Chief Financial Officer Masaru Kato noted this week that around 5,000 workers would be taken off the payroll with the sale of a chemicals business and a small liquid crystal display fabricator.

Workers at Sony's TV unit, which Hirai has vowed to return to profit within two years, may eventually share that same fate, a Sony executive has told Reuters on condition he wasn't identified.

GRAND ALLIANCE?

One possible option would be for a grand alliance with Sharp and Panasonic, bringing together their set making divisions with the backing of a Japanese government eager to safeguard jobs.

Nomura Holdings analyst Shiro Mikoshiba reckons such a solution could trim another 20,000-30,000 jobs at Sony, and mimic an asset-light strategy championed by Apple.

"As an idea it's good. It might not be a good idea for the taxpayer, but if it happens it will be lucky for Sony," said Mikoshiba.

There is a precedent in Japan Display, a company two thirds owned by the taxpayer that combines Sony's small LCD operations with those of Toshiba Corp and Hitachi Ltd.

Doing the same for TV would allow Sony to keep selling its branded sets without the burden of losses. Hirai has insisted he will keep television at the heart of a strategy to seamlessly link TVs, mobiles and other Sony gadgets. Hirai, who rose to prominence by reviving Sony's PlayStation games business through cost cutting, will oversee the consumer electronics business.

In December, as consumer electronics chief, he ended a 7-year production tie-up with Samsung that forced Sony to buy LCD panels at a price that meant every Bravia TV set was made at a loss.

Sharp, the maker of Aquos TVs, this week increased its full-year net loss forecast, and has recently sold much of a prized, but under-used LCD plant, and a 10 percent stake in itself, to Taiwan's Hon Hai Precision Industry - another sign of a shift in the balance of power in Asia's technology sector.

Panasonic has shed around 17,000 jobs as part of a broader restrucuring, and expects to sell fewer flat-screen TVs.

NEXT HIT

Investors will want to hear more from Hirai than just cost cutting.

"Sony has to consider how it's going to come up with the big hit product," said Nomura's Mikoshiba.

For Hirai, growth lies in networks - a goal pursued by Stringer. In February, Hirai said he would widen the PlayStation gaming console online network to integrate all Sony devices, replacing three online content delivery platforms it currently operates. He has yet to spell out the detail on that.

"Sony has been talking about networks for a decade. It's probably time for Hirai to say something new," Mikoshiba said.

And growth is likely to need cash.

Sony's latest earnings revision - its fourth in a year - will lower its shareholder equity ratio to 15 percent from 17.2 percent at end-2011, according to Reuters data. At end-March last year, Samsung's shareholder equity ratio was around 63 percent. The higher the ratio, the more shareholders would stand to get back in the event of a company going bust.

Sony says it has no current plans to raise money.

• A Permanent Economic Emergency