Democrats on a House Judiciary subcommittee scuttled key provisions of a proposed balanced-budget amendment to the Constitution yesterday, leaving behind a bare-bones version they hope will be acceptable to very few members on either side of the controversial issue.

The Democrats, who would be delighted to see the amendment languish and die, put it in a watered-down form that bears only superficial resemblance to the one the Senate approved with President Reagan's support this summer. Then they adjourned for an unspecified period without approving anything, so that future action is uncertain.

If ever approved by the full Judiciary Committee, the new device would give House members the chance to vote on something nominally called a balanced-budget amendment that would carry little of the legislative force of the Senate's version.

This first House action on the controversial election-year issue reflected conflicting pressures that have forced at least a semblance of action. The House Democratic leadership and Judiciary Chairman Peter W. Rodino Jr. (D-N.J.) are opposed to a constitutional amendment but also realize that many members in both parties want some vehicle to vote for just before the off-year elections this fall.

Meanwhile, the Democratic leadership has begun work on still another vehicle for floor action, if needed. Rep. William J. Hughes (D-N.J.) said he is a member of a task force appointed by Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) to draft an alternative that would be a statute instead of a constitutional amendment.

Hughes said the group probably would propose a statute requiring Congress to start passing deficit-free budgets, probably in 1986, and describing budget practices Congress must follow in the interim to meet that deadline.

Sponsors of the original balanced-budget amendment in both houses have said that a simple statute would not satisfy them, insisting that only a constitutional amendment could discipline Congress to avoid deficits.

The Senate-passed version would let Congress adopt unbalanced budgets only by three-fifths votes of both houses unless the country were at war. A separate majority vote would also be required for revenue increases greater than the previous calendar year's increase in national income.

A similar version has long been pending in the House committee, but an effort to force it to the floor by a discharge petition has fallen short of the required 218 names and has apparently run out of time.

The subcommittee began with the original version yesterday and then chopped it up with two amendments offered by Hughes.

One eliminated the entire tax-limitation section that Rep. Henry J. Hyde (R-Ill.) protested was "the heart of the bill." The change would place no limit on the amount of revenue Congress could raise each year to cover a deficit; proponents have consistently said this would render the amendment meaningless.

Hughes said "it doesn't make sense" to tie each year's revenue base to a previous year's growth in national income.

The second Hughes amendment would bar unbalanced budgets only for a "fiscal period" instead of in every fiscal year as the original version proposed. "Fiscal period" was left undefined, but apparently could embrace several years.

Passed on a voice vote, the amendment also would allow three-fifths of the members of each house present and voting to create a deficit, instead of three-fifths of both memberships, as originally proposed.

Although most Republicans on the subcommittee voted against Hughes' amendments, it was clear from their statements that they, like the Democrats, were dissatisfied with the constitutional amendment in the form passed by the Senate.