Approx. 10 minutes after start without Problems a beep tone starts.
Approx. every half second.
Master caution is dark
Can you please give me a hint,
what the reason could be ?
And I don't know how to stop/solve it.

Thanks

Are you in the air? If yes check the press panel. Are you at the ground? Which phase?

I am in the air.
Rising.
What is press Panel ?

I did searches with "press Panel" in all Manuals
and got no results.

Pressurisation panel. In the air the beep most probably is that your cabin is not pressurizing 

Dear Chris,

thgank you for your hint.
The Packs were off.

I turned it to AUTO.
I had no more warning tones.

But as a beginner I still don't exactly know what the PACKS are good for.
But I'm on the way to learn all those matters.

Best regards.

32 minutes ago, attila20 said:

 

But as a beginner I still don't exactly know what the PACKS are good for.
But I'm on the way to learn all those matters.

 

PACKS are kind of air conditionning units they are regulating the air flow and temperature

if you're a beginner I strongly advise you to reads manuals, maybe not starting with the FCOM but some tutorials etc...when you will be more advanced just read the FCOM and FCTM (it's the real world manuals, you will find real world procedures, system description, etc..)

I made this exact mistake yesterday and eventually figured it out, but wondered - is that how it alerts in the real 737?  Audio beeps but no warning message or text?

(It took me a while to resolve the issue but rather than admit to not reading the manual, I’m going to claim I was simulating hypoxia).

Thanks,

Mike Frantz

56 minutes ago, frantzy said:

I made this exact mistake yesterday and eventually figured it out, but wondered - is that how it alerts in the real 737?  Audio beeps but no warning message or text?

(It took me a while to resolve the issue but rather than admit to not reading the manual, I’m going to claim I was simulating hypoxia).

Thanks,

Mike Frantz

You should not be relying on system alerts.  My practice is to glance up at the cabin altitude/dP gauge as part of the climb through 10000 feet along with turning off lights, all I need is a quick glance to ensure there is a positive dP.  This is something i started doing decades ago real world after I didn't notice the cabin  pressure failure until passing through 16000, and that was due to recognition of onset of hypoxia, which can be easily missed unless you know what it feels like.  I've checked the gauge every climb since so it carried over into the simulation world.

The beeping you are referring to is called the cabin altitude warning horn. Fun fact of the day, it's the same horn that is also used for the takeoff configuration horn. For example, try to take off with the parking brake set and you will hear the same horn that you have been hearing at altitude.  In real life training for the 737 they make sure you know this.

11 hours ago, frantzy said:

I made this exact mistake yesterday and eventually figured it out, but wondered - is that how it alerts in the real 737?  Audio beeps but no warning message or text?

(It took me a while to resolve the issue but rather than admit to not reading the manual, I’m going to claim I was simulating hypoxia).

Thanks,

Mike Frantz

. This was one of reasons that brought down Helios flight 522 back in 2005 near Athens (https://en.wikipedia.org/wiki/Helios_Airways_Flight_522). I beleive there are modifications made after that accident.

Thank you to you all, explaining and solving this issue.

If you google PMDG737NGX tutorials you will find all kind of links that will show you how to set up the PMDG737NGX starting cold and dark.

here is one such link

https://www.youtube.com/watch?v=XZyImY8679k

This is what I did after buying this aircraft I have watched several of these videos and learned a lot from them

17 hours ago, frantzy said:

I made this exact mistake yesterday and eventually figured it out, but wondered - is that how it alerts in the real 737?  Audio beeps but no warning message or text?

(It took me a while to resolve the issue but rather than admit to not reading the manual, I’m going to claim I was simulating hypoxia).

Thanks,

Mike Frantz

Like Dan mentioned consequences in the real world regarding pressurization problems have larger consequences then the sim - for that reason I'm sure RW pilots are checking the pressurization on every climb out. Plus the first and second items in the after takeoff checklist would ensure that you turn on the pressurization system.

I've taken off with the over wing exit doors open, didn't figure out anything was wrong till the pressurization warning went off (obviously I wasn't checking the pressurization gauge on the way up - nor the exit door warning lights). Even still probably would have had some panicking flight attendants in the cabin beating down the door in the real world prior to takeoff.