The yellow, steel-barred door clanged shut behind the 10 teen-agers as they entered the Prince George's County jail for the first time.

A heavy wave of hot air met them as they climbed the stairs to a world they had known previously only through streetlore.

Before they left this realm, where men spend the long hours of their days restricted to an area not much larger than two bed-rooms, they would hear tales of broken homes, lost loves, mental frustration and homosexual advances.

Two of the boys, long-haired and barely 14, were solicited by one of the men.

"You look awfully good," the man offered from behind the thick yellow bars. "Why don't you come on in here and watch some television?"

"This place is worse than hell," said David who had been convicted of breaking and entering. "I don't want to be nowhere near this place.

Another youth remarked, "Before they threw me in here, I'd dive through a second-floor courtroom window to escape. I think I'd rather die than be tossed in one of themthings (pointing to the cellblock)."

Fortunately for the youngsters, ages 14 to 17, their visit to the county jail was just that -- a visit. They were participating last week in an experimental program called JOLT (Juvenile Offenders Learn the Truth), sponsored by an inmate fraternity known as the Centennial Slammer Jaycees and by the 4-H Community Restitution office, a private, non-profit group that works with young delinquents.

The program's chief aim is to give juvenile offenders a second chance while encouraging them to stay clear of the police and jail.

"We want to let these kids know that this is the reality they will face if they continue to get in trouble," said JOLT coordinator Laverne Barnum. "We aren't trying to scare any of them, but we'd like for them to know that jail won't be all peaches and cream."

The program is backed by county and federal money, and its clients are young offenders between 13 and 17 who have committed crimes such as breaking and entering, assault and shoplifting.

All have been convicted in juvenile court, and all have been referred to the program by a judge or juvenile officer.

JOLT activities are spread over two days. On the first day, the teen-agers visit juvenile court and Boys Village, a Prince George's detention center for youths convicted or accused of crimes not minor enough to make them eligible for release but not severe enough to send them to jail or training school. For most of the JOLT participants, Boys Village is familiar territory.

On last week's tour, a lanky boy pointed to one side of a Boy's Village cottage, smiled and said, "Hey, fellas, that's my old bedroom. My bed almost fell apart while I was sleeping in it."

A few of the other boys laughed.

Only a few times did the boys seem serious. They appeared shaken when they saw an isolation cell for juveniles too disruptive to live with others in the cottages. And a walk through one of the cottages prompted a boy to remark, "I knew people who prayed here who hadn't prayed for 10 years. They were tired of being away from home."

Gloom prevailed on the second day of the tour, however, when the boys visited adult court and, finally, the county jail. In the jail they talked to inmates, some of whom were serving as many as 60 years.

Unlike "Scared Straight," a program tried in other prisons and jails on the East Coast, JOLT does not allow the inmates to use scare tactics to discourage juveniles from getting into trouble. "Scared Straight" had been criticized because inmates were allowed to threaten juveniles with physical abuse, and because there was no follow-up counseling after the rap session with convicts.

"This facility (the county jail) is enough of a scare tactic in itself," said James O'Neill, spokesman for the detention center. "Reality will get the message across."

Leaders of the Centennial Slammers Jaycees, who conceived the JOLT program, held two closed sessions with the juveniles. They told them what it was like to be in jail -- away from their families, their girl friends, and the world of freedom and fresh air.

Between the sessions, the boys were taken on a tour of the facility, to see and talk to some of the 200 men who inhabit the old half of the Prince George's jail.

All the prisoners there are convicted felons. They are cramped into quarters so crowded that in some places there is barely enough room to get out of bed. Some have no beds, but sleep on pallets on the floors of the large common cellblocks. In some cases, the cellblocks are home to as many as 60 men.

"It gets so hot in here, sometimes you just feel like walking around in this place naked," said one man with a scraggly beard and deep-set eyes. In fact, several of the men wore little more than their underwear.

"Once you get in here, this becomes your whole world," said the inmate coordinator of the tour. "Anyone in these cells will tell you this is no place to be."

"When you're behind these bars, you're helpless," he added. "It takes away your sense of pride and your ability to take care of yourself. You become a burden to the people you love and there is no place to get rid of all the frustration. You can't even be sure that if you get a pack of cigarettes to smoke away the irritation and frustraion that somebody won't steal them."

The inmates also described the difficulties of living under a system that restricts where they can go, when they can see their families, and when they should eat and sleep. They said breakfast is served at 5 in the morning, lunch at 11, and dinner at 3.

"This place is full of mental frustration," said one prisoner."You have to learn to deal with a lot of things. It may be eating when they tell you to eat or it may be missing your parent's funeral when you feel you should be there. All I can say is: stay away from this place."

Throughout the tour the jail, the juveniles were met with a chorus of voices from prisoners shouting, "Stay out of here! Outside is where it's at. vThis ain't no place for y'all to be."

By the time the two-hour tour was over, even those juveniles who joked about Boys Village appeared impressed by what they had seen in the county jail.

"I didn't know it was like this," said Kevin, 17, who was convicted of destroying public property. "It's dirty, funky, and too crowded for people to live in. I'd crack up if I was locked up. Nah, this ain't for me. I won't be getting into no trouble because I already have a rope around my neck."

As a follow-up to the tour, the juveniles will attend two counseling sessions to talk about what they saw in the jail and about goals they would like to set for themselves in the future.

"What we'd really like to do is trace the progress of the juveniles after we've taken them through the program," said Barnum, the coordinator."The only problem is we might have some difficulty in getting hold of juvenile records. A lot of files are confidential."

Last week's tour was the second in a series. Barnum said if all goes well, the JOLT program will handle 10 new juveniles each month.