Each member of the Stanley Cup champions will receive a check for $15,000. That is a prime reason why checks of another sort, frequently missing during the regular season, become an important factor in playoff competition.

For that kind of money, players are willing to become physical. A year ago, Toronto and Philadelphia became so physical that eight Stanley Cup penalty records and an assortment of courtroom appearances overshadowed the numbers on the scoreboard.

Those two teams take their memories of bitterness into another best-of-seven quarterfinal series, opening tonight in Philadelphia. It is one of three rematches, the others pairing the New York Islanders against Buffalo and Boston against Los Angeles.

The lone quarterfinal series containing something new also boasts something Blue. The St. Louis Blues assume Chicago's 1976 role as Smythe Division winner and quarterfinal cannon fodder for the defending champion Montreal Canadiens.

Philadelphia, the Islanders, Boston and Montreal are hosts tonight and Wednesday. Their underdog opponnents get home ice Friday and Sunday, then the teams alternate sites, if necessary, on April 19, 21 and 23.

Here is the rundown on each series: Toronto at Philadelphia

Followers of this series are reminded of the provision of Rule 29 (f), which stipulates that a player receiving two game or gross misconduct penalties in the playoffs will be suspended for the next contest. A third such violation will mean a two-game vacation.

Last year, as the Flyers prevailed in the maximum seven games, the two teams served a total of 157 penalties, including 12 games misconducts, for a total of 525 minutes. It wasn't until October that charges against some of the more demonstrative Flyers were dismissed by a Toronto magistrate.

Just to show that wasn't simply an exercise of April Fools, the teams engaged in a wild free-for-all for national TV in Philadelphia March 7, when the Leafs posted their only victory of the season over he Flyers, 4-2. Philadelphia won two, with the fourth a 5-5 tie.

Toronto has one superb line, centered by Darryl Sittler (90 regular-season points) with Errol Thompson, injured much of this season, and Lanny McDonald, another 90-point man, at the wings, It was McDonald's hat trick that dispatched Pittsburgh in the preliminary rounds. On defense, Toronto features high-scoring Ian Turnbull (79 points) and Borje Salming (78).

The Flyers' strength is at center, with Rick MacLeish (49 goals) developing into a superstar after missing last year's playoffs with a knee injury. Bobby Clarke (89 points) is a bit slower, put just as wily.

Radio: 1210, although Phillies' conflicts could scramble the signal. Buffalo at New York Islanders

The Islanders, an inept checking team, have a habit of clamping the Sambres' heart, center Gil Perreault, in his own zone, before he can begin his dangerous rushes up the ice. That is the formual that helped New York capture last year's quarterfinal, 4-2, as well as regular-season honors this time, 3-1.

New York's Chico Resch (2.28) had the NHL's best goal-tending average outside Montreal. Buffalo rookie Don Edwards proved most effective when regular goalie Gerry Desjardins was hurt, but playoff pressure has a way of affecting the most composed of youngsters.

The teams rank among the NHL's top four in power-play goals, but they will tend to nullify those statisfics with the fact that each is also among the top four in penalty killing. Buffalo permitted just 38 extraman goals, a figure bettered only by Montreal's yeild of 28.

This is likely to be a tight series, with the possibility of frequent overtime. Those games are won by the team making the fewest mistakes, and that team is the Islanders.

Radio: Try 550, but only if you have a super-powerful receiver. Los Angeles at Boston.

These were among the NHL's hottest teams at season's end. Boston won its last five, including road successes in Buffalo and Long Island, to finish third overall and avoid the spector of a semifinal collision with the Canadiens. Los Angeles was unbeaten in its last six, earning preliminary-round home-ice advantage that proved crucial in its three-game ouster of Atlanta.

The Bruins' problem is to avoid cheap penalties, because the Kings own the NHL's most potent power play. The extra-man combination, triggered by point guardian Marcel Dionne, converted 68 of 253 opportunities. Dionne, a 53-goal scorer, collected 14 on the power play, one less than Tom Williams and one more than Butch Goring.

The teams divided the season series, 2-2-1, with the Kings owning a 14-12 edge in goals. Last year the Bruins prevailed in a seven-game series that saw the Kings gain two overtime victories.

Rogie Vachon gives the Kings a big plus in goal, but Boston works harder. If Vachon can instill his spirit in his teammates, this series holds upset potential.

Radio: 1030 comes through loud and clear. St. Louis at Montreal

On Jan. 12, the Blues mopped up the Canadiens 7-2, for Montreal's worst defeat of the season. Emile Francis is no doubt reviewing the tape of that game trying to discover the magic touch that made it possible. The fact that the Canadiens won the other three meetings, by an 18-4 margin, lends doubt that he will find it.

The Blues received $2,500 per man for finishing first in the Smythe Division. They will get $2,500 each as losing quarterfinalists.

Radio: 1120 for staticky English, 700 for flowing French.