Very new-need help on I believe failed ic chip

Thread Starter

mezzmen

Joined Jun 27, 2017
8
Hi this is my first post..i am new to learning everything electronics.. so I am stationary engineer and I had two auto sensing hand dryers fail on me. One would just keep running and the other would not run at all. I replaced both with a new board from other units and now they work.. but the robbed units still need fixing .. so something on the board is broke.. looking at both of them there is a lot of oxidation on the same ic chip..on the robbed boards it's very clean..do you think unsoldering and cleaning up the legs that have Oxidation might be a chance it can fix it or should I just order a new parts .. sorry if my terminology is way off, I am very new but thanks for any input .. in the picture it's the ic chip on the right I think is the problem
 

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Thread Starter

mezzmen

Joined Jun 27, 2017
8
the trigger chip as you called it looks bad just looking at it again, I'm guessing it triggers the blower motor on and off so it would cause those problems I was talking about.. I'm not sure though
 

AlbertHall

Joined Jun 4, 2014
10,022
First, try using plenty of water and a stiff brush around the area. Make very sure it is dry again before applying power to it.
 

MrChips

Joined Oct 2, 2009
21,326
Post a photo showing the whole board.
There is a NE555 timer for the time delay and a MOC3014 optoisolator. There must be a power thyristor on the board as well to power the blower and heater.

Most knowledgeable members here on AAC can reverse engineer that board and could trouble shoot it on a workbench and an oscilloscope.
 

MrChips

Joined Oct 2, 2009
21,326
There appears to be commonly available components on that board:

Q1 - 2N3906 PNP BJT
Q2 -
Q3 - 2N3906 PNP BJT
Q? - MAC223A6FP thyristor
U1 - LM324N op amp
U2 - CD40106BE hex Schmitt trigger
U3 - NE555P timer
U4 - MOC3041 optoisolator
VR1 - 3-terminal voltage regulator

Now if you tilt the board to show us the markings on Q1 and Q3 or supply us with the markings.
What is the full marking on the MAC223?

First thing to do is buy some replacement MAC223. I bet they would be the first thing to go bad.
 

Thread Starter

mezzmen

Joined Jun 27, 2017
8
I'm gunna have to wait until tomorrow to instal to see if cleaning helped it. The 555 timer looked really bad on the pins tool so I cleaned that up
 
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Thread Starter

mezzmen

Joined Jun 27, 2017
8
I cleaned the pins on that trigger chip with fine sandpaper and it actually works now where it didn't work before .. thanks.. as for the other board i did the same ,I'm not sure but it seems to work. But the problem it was having where it would just keep running the blower motor without stoping would someone know does that sound like there's a problem with one of the certain ic chips like the 555 timer or the other ones or can it be anywhere in the circuit not being a ic chip
 
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