Vu+ Duo just red led, no further activity repair story.

This motherboard I have gotten a while ago from a member, and this is about my found defects and solutions regarding this motherboard.

Problem, just red led, no further activity, front display also dead.
The famous cap had been replaced recently, so it could not be the problem.
Psu problem could not be, I use my own.

Jtag,
Tried but got no connection, so the problem was worse than I thought.
Serial port and usb ports also failed.

Serial port,
I have the RS232 PCB tested on another working motherboard and it was defective.
After replacing the rs232 chip it works well again.

Security chip,
Also tested the security chip, and was also defective, also unrepairable.

Motherbord,
Now the test with the motherboard, with a working RS232 board, and a working security chip.

research,
Box was still dead, just a red LED.
Jtag gives no connection, USB, Serial port, display, etc did not work.

All the main voltages were present, but a comparison of the voltages from a working motherboard I noticed that a few voltages were not present or lower than normal around the CPU.
As a result, I had the idea that it could be a Cpu problem.

My risky trick,
After heated the CPU with hot air with the box switched on, I saw some strange characters appear on the front display, and terminal data appears on my screen.
So I had the feeling that I was right.
But beware, this method is risky, but it could be the quickest way to detect these types of errors

Cpu fix attempt,
Box obviously turned off, cpu heat sink removed, cpu covered with kapton tape, and the motherboard/cpu preheated according to schedule.
Allowed to cool down.....

Motherboard check,
Display turns ON, message is Starting...

Serial Port check with only the serial cable,
Terminal data output works.

Serial Port check with the rs232 adapter between,
Terminal data output is okay.

Usb port check,
Usb port failed.

Jtag check,
Connection is possible, so immediately the cfe file upload.

Usb port check,
Uploading image file starts, but after awhile it stops, further no activity.

Usb port 5v measurements,
5v present, but drops slowly after a while, this happens on all USB ports.
On the motherboard are three (AP1212) usb chips
Which there may be responsible for I needed to gamble.
I gambled on the front USB port because this is mostly used, which is the U412.
Replace, and solved the problem.

Usb port check,
Upload software starts, and succeeded.

Motherboard check,
Motherboard start properly, no problem, also a image on the tv screen via hdmi and scart.

Finally,
The motherboard is working again, the main problem was most likely a cpu problem.
And guessing that the other damage has come through many attempts to solve the problem.

Faulty parts,
CPU, hot air fix.
Rs232 chip, replaced.
Security chip, replaced.
One USB chip, replaced.

So, it's working now, but reheating the cpu does not guarantee any long-term of use.
Often the problem comes back after a time.
However this member donated this motherboard to me so that's in this case not a issue.

It was an educational project, and a challenge to find and repair the errors.

All the best about hardware/support from Johnny_B, link :
http://jb8a8f8.com
http://jb8a8f8.nl