Hallo everybody, i have an DM800se witch don't start. It happen nothing when plugged in Power. No LED On Port 1100 is everything 0 Volt I have made some pictures witch shows what i have messured. I have use Search-function and has read a lot, but i can not come forward. I stop on device U1202 witch operate not correctly. I am not able solder Units like U1100, but i am very motivated to find out why this Box is striking. Thanks
Before thinking of a 12 to 5v issue, check the Ground inductors L1117 and L1004, check if they are not interrupted.
Hallo Johnny L1117 and L1004 seems to be okay. L1004 was removed and checked L1117 was checket on board.
Yeah in that case you may assume that the U1100 has some issue, in any case, based on your ohm measurements I have no reason to doubt about the voltages circuits, all seems to be fine. Maybe it has a switch On issue, check the Q1104 and the parts on it which is for the U1100 pin 9/26 on/off switch. This U1100 pin 9/26 must have a voltage between the 1.5/2v dc, when lower or missing, then the U1100 will not be active (switched off). more about this, see this U1100 schematic. Another option is to remove the whole 12v to 5v system, and modified it with a dc to dc converter as this topic shows. The box I had modified with it is still working without issues.
I have measured 1,5 Volt on U1100 pin 9/26. So i can assume Q110o is damaged. I will prefere your solution, with remove the 5V system, and replace it to Step-Down converter. I will let you know, if it was successfull. Thanks
Yes, based on the info you had given, then it seems to be a defective U1100, in that case it's cheaper to modified it with a DC to DC Step - Down Module as for example the LM2596 DC to DC Step - Down Transformer Module which can be found on ebay. In any case, this motherboard needs the 5v, most of all other voltage circuits rely on it.
Because i have to wait til Step Down converter is shipped, i have time to make additional meassures. Pleas have look to D1100 witch is a double Diode. It looks to me like a defect in upper Diod . What do you think?
Defective U1100, because only the ohm values which are directly related to this ic are wrong, all others as the 5v ohm values are normal.
Thank you for your help The box is working properly again. I have removed the 5V area and replaced it with a step down converter. I have worked according to the instructions you have suggested.