Sencor SVC7020BK robot vacuum cleaner problem

[stj]

q21 may be partially shorted,
the base shouldnt draw enough current to heat a resistor

[Awesomerp]

It still gets hot after replacing Q21, but thank you for all the knowledge and tips really appreciate it I will try to figure it out what's going on when i will have some spare time. At charging and why it stops driving.

[Awesomerp]

As I understand the main objective of IC4 is when the positive inputs are higher than negative inputs, to provide an output of whatever voltage is on a pin8 which(vcc+) and step it down with 100k resistor to 5V? And if the negative input is higher than positive the signal will go to Pin 4 ground?
But I don't really quite understand why there has to be 2 op amps in this comparator. Also do voltages of both of the outputs add up and then are being converted to 5V through a 100k resistor?

[stj]

the comparaters are active-low
if either trips then the mcu thinks there is a fault with either the 8.3v or the battery voltage.
if both voltages are u.k. then the output should be high because of r1

if the output is low then either one of those resistors in the divider circuits is bad or the chip is bad.
those chips can slowly drift out of spec which is why i pointed it out some posts back.

[Awesomerp]

thank you

[sam_sam_sam]

Originally Posted by Awesomerp

thank you

I would also recommend changing the LM393 as well for the same reason as what STJ mentioned earlier

[Awesomerp]

thanx!

[Awesomerp]

Could someone help me to identify what these codes mean below LM393 part.
"78K"
"D83D G4"
Maybe there is a website where I could find the datasheet of this exact one and see the specs of it to choose a similar one to buy.
Or is it enough to choose the same pin out and size one?

[stj]

they mean nothing,
it's production tracking data

[Awesomerp]

I see, well ill use size and pin outs to determine the similar one then.

[stj]

it's probably an SOIC package