A ticking personality time bomb, John McEnroe, won again at Wimbledon today. The question is, can he succeed in his announced mission to defuse himself this fortnight and yet play the fire-eating tennis that made him a Wimbledon champion?

McEnroe's unimpressive 6-3, 6-3, 7-5 victory over Eddie Edwards today was accomplished amid a flurry of minor skirmishes that he once could have turned into war.

"For me, I was relaxed," said McEnroe, dead seriously, adding, "I'm trying to laugh it off more." This was after jawing with linesmen, shushing spectators and whacking a ball so hard in anger at his own mistakes that the umpire issued "a warning, Mr. McEnroe, for ball abuse."

A third straight day of occasional rain here again delayed play, with the victorious Mark Edmondson (No. 12) and Buster Mottram (15) the only other seeds in action in either men's or women's play. Second-seeded Jimmy Connors plays John Alexander in Thursday's top men's match, while top-seeded Martina Navratilova begins women's play against Beth Norton.

Even as the "relaxed" McEnroe spoke at a press conference, he clutched his arms about his body, as if in a straitjacket. As always, there was a hunted/haunted look about his eyes, flitting here and there without settling anywhere. His voice was a defensive whine.

What he wants, said this 23-year-old multimillionaire who has won three U.S. Opens and a Wimbledon, is to have some fun at work.

With melancholy, almost as a plea, McEnroe today said, "I plan on enjoying my tennis career at some point. Hopefully, as time goes on, it'll be easier."

For now, the time bomb is yet ticking, and the dread noise was audible to everyone at Court 1 for McEnroe's second-round match. Erratic with the serve that is among the game's best, McEnroe compounded his difficulties by botching volleys galore against the overmatched Edwards. If McEnroe at his best gets a grade of 100, today's performance was an 80, good enough to pass but not the kind of work that will win big matches here.

Edwards' only shot at victory today was to have McEnroe play right-handed, but McEnroe discounted the seemingly obvious explanation that his work suffered from disinterest. He dug back in his memory bank to find that Edwards beat him in a college match once. "I wasn't taking him lightly," said McEnroe, whose career earnings of $3.6 million lead Edwards by about $3.2 million.

McEnroe's concentration was suspect, anyway, as he let the extraneous noise common to Court 1 annoy him. Time and again, he waited for fans to take their seats. He asked for quiet. All this is nothing but a player's attempt to wake up to the job at hand. McEnroe's occasional jibes at the chair umpire fit the same classification, since, by McEnrovian standards, they were sweet nothings.

The ball-abuse warning came when McEnroe messed up a volley and, since he was near the net anyway, smacked the extra ball at the net. Only, it clipped the tape and sailed on to the end of the court. The umpire, George Armstrong, immediately warned McEnroe against another such display, the penalty being loss of a point.

McEnroe argued for a second, then went to serve again. As he bounced a ball, he had another thought. So he stopped and walked back to Armstrong, chattering away, and then the umpire on his microphone said, "No, it didn't go out of the court. It's still abuse of the ball."

McEnroe gave up meekly.

"I don't want to go through what I went through last year," said the fellow who last year won his sport's biggest prize here. What he meant, presumably, is the rest of it: beginning the first day here last year, he misbehaved so often and so outrageously while playing so wonderfully that one of four biographies on sale here is titled, "McEnroe: Superman or Superbrat?"

To avoid a second coming of that firestorm of controversy, McEnroe is making a concerted effort to be a good guy this time. Twice today he laughed at obviously mistaken calls, shaking his head in dismay where a year ago he might have called in artillery on the umpire's chair.

One school of experts believes McEnroe's rage is the fuel that fires his genius. Without it, he is still a skilled player but something distinctly less than, to pick a name, Bjorn Borg. These experts point out that McEnroe has not won a tournament since last October, a time period also distinguished by his relatively calm behavior.

Today's match, by these measurements, is another piece of evidence that McEnroe now is indeed less than the player of '81. Only fitfully did he produce magic with his racket.

"My rhythm was off serving," McEnroe said, "and I missed so many easy volleys. Incredible misses . . . I'm frustrated with the way I played today. It was not one of the great matches. I won the points I needed, and that's the only thing I'm happy about."

Well, there is one other thing that kind of semi-pleased the young McEnroe in a wishy-washy sort of halfhearted way.

After his first-round victory Sunday, he revealed that Wimbledon had not yet given him his championship trophies. In response, Wimbledon offered a series of alibis bought only by the naive who believe Wimbledon would forgive McEnroe for skipping its annual champions' dinner at tournament's end.

Within an hour of McEnroe's complaint, the trophies were delivered to his father.

"From what I've heard from my dad, they're nice trophies," said McEnroe, who added that he hadn't looked at them. "I'm happy I got them."

McEnroe said he wasn't holding the trophy deal against Wimbledon. "They just put their foot in their mouth by making it seem like they did the correct thing all along," he said.

Tick, tick, tick.