* Nikkei on track to fall 0.5 pct for the week
* Chip equipment makers contribute to hefty declines in Nikkei
* Nissan falls on poor 1Q results
TOKYO, July 28 (Reuters) - Japan's Nikkei share average fell on Friday morning after tech shares dropped sharply following weakness on the Nasdaq market, while investors stayed cautious as the dollar slipped against the yen.
Semiconductor equipment makers tumbled, with Tokyo Electron Ltd diving 6.2 percent and Advantest Corp declining 2.7 percent, together contributing a hefty 44 negative points to the Nikkei benchmark.
By the midday break, the Nikkei dropped 0.4 percent to 19,994.54. For the week, it is on track to fall 0.5 percent.
Investor sentiment was also hurt by the resignation of Defence Minister Tomomi Inada over a series of gaffes, missteps and a cover-up at her ministry that have contributed to a sharp plunge in public support for Prime Minister Shinzo Abe.
"The Japanese market's upside has been capped partly due to Abe's falling support rate," said Masashi Oda, general manager at strategic department at Sumitomo Mitsui Trust Asset Management.
Over the past few weeks, the suspicion of scandal over favoritism for a friend's business and missteps by cabinet ministers have taken a toll on Abe, who until recently was favored to win a third three-year term as party leader, and hence, premier when his current term expires in September 2018.
"There is no successor's name coming up yet so we should not be overly cautious, though investors probably won't chase the market higher for a while," Oda said.
On Friday, Japanese companies' mixed earnings results attracted attention, with Nissan Motor Co falling 4.2 percent after its first quarter operating profit fell 12.8 percent on the year.
Construction equipment maker Hitachi Construction Machinery soared to a nine-year high at one point after its quarterly operating profit jumped 584.5 percent on the year to 16.7 billion yen ($150.30 million) thanks to strong demand in China and North America.
Daiwa Securities tumbled 4.6 percent after its quarterly net profit fell 21 percent, hit by weak FICC (fixed income, currencies and commodities) trading revenues.
The broader Topix shed 0.2 percent to 1,623.79. ($1 = 111.1100 yen) (Editing by Jacqueline Wong)