triac & terminal switch tda1085c

Thread Starter


Joined May 27, 2019
I have a problem with a tda1085c circuit.

The board has 2 terminal switch with a moving shaft.There are 3 positions. Position 0(motor stopped) posistion 1(right-handed rotation) and position 3(left-handed rotation).At the same time, moving with the shaft a potentiometer to adjust the speed.
if it has been pressed position 1 or 2 and after turn on the main power switch(230v), everything is ok with universal motor.
If i turn on the main power switch and press the terminal switch from position 0 to position 1 or 2 the motor starts with high speed and stabilizes in the right speed.The change of direction takes place with relays.

I have tried to change the potentiometer, but the problem is with the spikes from switches and the triac(bta26-700b)
Also i have tried to put electrolytic capacitors on switch contacts and gnd, but the problem remains.

Sorry about my english.
Could you help me?
Thank you