TV lift board replacement

I need some help finding a board to replace the one that burnt out on my TV lift in my travel trailer. It operates off of 12v and drives a motor to raise and lower a tv using a screw gear. There is a momentary rocker switch that you press once to raise the tv and press the opposite side to lower the TV. The board recognizes the limit of travel by measuring the current. So you press up and the tv rises to the upper limit when the motor current increases at the top the motor stops. Some for going down. The label on the board says H-bridge motor control w/current monitor. I have looked at several H-boards, but can't find any that meet the same functionality. Any help would be great. I will contact the original manufacturer, but I doubt they will be helpful, and it is a holiday weekend.

 

Well if we are going to try and repair this one, I should give you more details. This board powers on, but immediately falts when the button is pushed. Red LED comes on when it falts. Wait a minute and it goes off, push the button again and it falts. Do this enough times and you might get it to raise the tv once. This board has an optional remote board (green) on it. I don't have a remote for it (was never given one). Thought about removing that sub board to see what happens. The board gets very hot when plugged in. Specifically U4. I believe this is a mosfet. I know a few things about board components, but more on the noob level of diodes and resisters. I can solder very well I have no doubt that if I could identify a component that needed to be replaced I could do it. Unless it is a microchip. My best guess is the board is reading an incorrect current draw and shutting off as if the motor has reached the limit. I have not checked current draw of the motor, but it seems to be operating fine when 12v is directly applied. Hope this information helps and thank you for your help.

 

Thank you for the information. I will check as you are suggesting, but I have checked for obstructions and I tried to operate with no load on the motor. It was doing the same thing. The voltage regulator or other parts in that area get super hot. Hot enough to melt the hot glue used to hold the board in its case. I will test voltage on outputs.

 

Thank you again for the help. I checked the voltage regulator and I got 12, 0, and 8.5. 8.5 sounds a bit high and makes me feel that this is my problem.

 

Can I completely remove the voltage regulator since I don't use the daughter board?

 

I lifted the 12v pin removing power to the daughter board. There is no more heat from the voltage regulator or from the chips on the daughter board. The board still seems to function properly, I don't have the motor with me to fully test, but I have a good feeling this fixed my problem. I will update when I reassemble.

 

Edd, thank you for your help and information. I did lift 12v pin from U4 and I have reassembled the lift and everything is working properly. It is absolutely brilliant that picking up one pin seams to fix my problem, I was going to buy a new board, but with everyone's help I was able to fix with a workaround. Edd, after looking at your comments about supply 5+ to R13 & R12, I am confused to why it does work properly as it is. Currently to initiate a motor lift cycle manually you ground Q3 or Q4. Love all the work everyone has put into this and I am learning more than I expected to about this type of circuitry. Thanks everyone again.