Pioneer Receiver is powering off after turning on for 4 sec...

http://audio.manualsonline.com/manuals/mfg/pioneer/vsx819hk.html

It's in the manual. Page 12.

Resetting the Main Unit
Use this procedure to reset all the receiver's settings to the factory default. Use the front panel controls to do this.
1 Switch the receiver into standby.
2 While holding down the BAND button, press and hold the STANDBY/ON button for about two seconds.
3 When you see RESET? appear in the display, press AUTO SURROUND/STREAM DIRECT.
OK? shows in the display.
4 Press STEREO/A.L.C to confirm.
OK appears in the display to indicate that the receiver has been reset to the factory settings.

You need to determine what is overheating. For example if it uses a fan is that working? It it blocked with dust.
Operating the unit with the top cover off will quickly tell you which part is overheating. You can wait till it shuts down, then carefully, with it now unplugged, search for the hot parts. If you find only one overheating on it's own replace it.
Don't burn yourself!

Sounds like your "friend" has cooked something. It could be one of your speakers (do they all sound ok for the 5 seconds it runs?), or it could be the receiver....
I would try disconnecting all the speakers and see if it stays on. If so, it may be one of the speakers. Connect them one at a time, and see if you can tell.

sounds like a blown amp channel. you will have to take it in for repair.

The Media Receiver is the tuner/connector selector box.
If the top is removed the Media Box goes into shut down mode. It requires resetting by a Pioneer Authorised Service tool.

Hi pat,

For pioneer Amp error:

It means that microprocessor has detected an abnormal DC voltage:

Speaker relay will be Off, then flash "AMP_ERR" on display.

If the AC plug is pulled off within 60 sec,

and then it is plugged in again, the unit will be reset for 60 sec.

I assume its blue tooth enabled! make sure its enabled in your ipod. sometimes it shuts off on its own. or try turning ipod comp off and unplug reciever for 30 sec then turn on and try

Hey,
This may be too late...
I got it from the field manual.

Trap Switch Reset Procedure
G-4, G-5, G-6, G-7, G-8
• Replace media receiver, plasma panel cover, or tape down HDCP trap switch.
If the model in question has the TV Guide option, the TV Guide
option must be turned off before proceeding.
• Using the customer’s remote control enter “service mode” by pressing the
following key sequence:
1. Press the “display” button then release the “display” button.
2. Wait between 3 and 7 seconds
3. Press and release the “<”, “^”, “<”, “>”, and “power” buttons in sequence.
• Panel will now turn on in “service mode”.
4. Press “muting” button 3, 4 or 5 times depending on model you are working on.
Until the display shows the “initialize” page.
5. Press and hold the “display” button until the error indicator (red LED) on
either the panel or the media receiver goes out.
6. Exit service mode by pressing the “power” button on the remote.

I had to try it a couple of times before I got it to work. I.m not too sure how to turn off the tv guide mode. I just held it in for a couple of sec,s.

Good luck

Press TUNE+ & AUTO SURR/DIRECT keys continuously for 2 sec. and it will tell you the fault it encountered if the receiver is in otherwise working condition.

I have vsx-d812 that has an AMP ERR in error menu. the troubleshooting was found to be Q696 and Q697 in the DC prot. area on "C" board, up near front toward diplay in center of c board. You can get access to error codes on VSX pioneer unit by pressing "enter" and "adv. surr." simultaneously for 2 sec. The display should show what error code you are experiencing. I believe there are three diff. error codes. 1) AMP ERR 2) OVERLOAD 3) BOAD ERR (not mistyped) I hope this helps pinpoint error code for ya.