L293D used to reverse motor direction 7.8 vdc

[rjsutton]

Doddy
im not using any breadboard etc im soldering directly to the L293d pins i dont physically have the space to have a breadboard
Ive been super careful to keep the heat down and not shorting with the solder ( between pins) that said the photo would not be clear enough
ive recreated with 5 no L293d and 3no lm708s and get identical readings and problems so dont think its a soldering problem
I dont understand why the power feed from 16 is looped thru push button + to pin9
is the drawing fundamentally wrong?

[Doddy]

Doddy
im not using any breadboard etc im soldering directly to the L293d pins i dont physically have the space to have a breadboard
Ive been super careful to keep the heat down and not shorting with the solder ( between pins) that said the photo would not be clear enough
ive recreated with 5 no L293d and 3no lm708s and get identical readings and problems so dont think its a soldering problem
I dont understand why the power feed from 16 is looped thru push button + to pin9
is the drawing fundamentally wrong?

Pin 16 (VCC1) is connected directly to Pin 9, according to your diagram. Pin 9 is the 3,4 enable pin - if HIGH (5V) then the outputs 3,4 (pins 11, 14) are enabled. if Low then outputs 3,4 go high-impendance (Read: OFF). So what is concerning you?

The other contact of the switch (marked CCW in your diagram) goes into the pin 10 (input 3, "3A") which drives through the driver chip one side of the motor to either +VCC2 or GND.

Describe the behaviour of the 5V supply - does it drop to 3.8 V in response to a button press?

EDIT: Just a thought as I was about to leave the house... wiring directly to pins, as far as I understand from your description you're completely disregarding the thermal requirements for the L293D - read the datasheet.