Having an issue with my chiller not turning off.

dstroy

Well-Known Member
@dstroy when testing these NPN transistors, you’re supposed to test six things because there are three poles, with each you switch the polarity on. When you put the probes one way and it reads say 12,000 ohms, when you reverse the polarity on those same 2 poles, is it supposed to always be
negative ohms? High ohms one way and negative the other? Or do I have this wrong?

Your transistors are npn according to their part numbers, just look up the part number and read the data sheets, those give you the values you want to test for. You already found what your coil resistance is supposed to be from the data sheet.

Now all you need is a bit more understanding of what the different components do, and then you’ll be able to follow circuits easily because they all make “logical sense” once you understand how components interact together, most circuits are designed in a similar way.
 

Jypsy Dog

Well-Known Member
@Jypsy Dog im gonna kindly ask you to please stay off of my thread If you don’t have anything helpful to say. I’m tired of your hate.
No hate... Waiting for SMOKE. Keep fumbling please.
Sounds like your Instructor is almost DONE with your lack of understanding. He's doing your homework FOR YOU!
 

Airwalker16

Well-Known Member
All of these stupid videos on YouTube just assume that my multimeter has a diode option. Besides one video I found. Basically from what I can understand he said is that you put the ohms on your highest setting and check the base and emitter for a reading. If it doesn’t give you a reading he said to switch the probes . He also said that if you get a reading with the probes either way on the base and emitter(poles 1&2), that it is a bad transistor. Is this correct? Because when I put the probe on my base and emitter, either way I get a reading. On BOTH transistors. @dstroy
 

Airwalker16

Well-Known Member
No hate... Waiting for SMOKE. Keep fumbling please.
Sounds like your Instructor is almost DONE with your lack of understanding. He's doing your homework FOR YOU!
I don’t get what you have against someone being kind and helping someone, who knows nothing AT ALL about PCBs, with a problem. He’s just explaining what to do, I’m the one doing the testing.
 

dstroy

Well-Known Member
All of these stupid videos on YouTube just assume that my multimeter has a diode option. Besides one video I found. Basically from what I can understand he said is that you put the ohms on your highest setting and check the base and emitter for a reading. If it doesn’t give you a reading he said to switch the probes . He also said that if you get a reading with the probes either way on the base and emitter(poles 1&2), that it is a bad transistor. Is this correct? Because when I put the probe on my base and emitter, either way I get a reading. On BOTH transistors. @dstroy
Yeah you do need a diode option to do a lot of tests. It’s a very useful function. Same goes for capacitance.

Testing transistors in this manner (resistance) only works for BJT, not FET so keep that in mind. Take a look at the transistor data sheet and ensure that they are bipolar junction, not field effect.

I don’t know how (I get that you told me how you did it but since you’re still learning, and don’t have someone there to help show you how I don’t know if your results are reliable) you’re testing them so I can’t say if they’re good or bad. Those transistors are really cheap though so if you want to replace them I think even RadioShack has them, they’re so common.
 

Jypsy Dog

Well-Known Member
I don’t get what you have against someone being kind and helping someone, who knows nothing AT ALL about PCBs, with a problem. He’s just explaining what to do, I’m the one doing the testing.
Just seen what a DICK you can be to others..... KARMA BABY.
 

dstroy

Well-Known Member
I think that it’s safe to say that the transistor that switches the heater relay is working correctly though, don’t you think? That outlet is only powered when it’s supposed to be because you checked that already. So we can assume that the entire circuit for the heater is working as designed.
 

Airwalker16

Well-Known Member
I don’t really understand what the transistor does necessarily. I’m just trying to find a component that tests wrong/bad.
 

Airwalker16

Well-Known Member
Yeah you do need a diode option to do a lot of tests. It’s a very useful function. Same goes for capacitance.

Testing transistors in this manner (resistance) only works for BJT, not FET so keep that in mind. Take a look at the transistor data sheet and ensure that they are bipolar junction, not field effect.

I don’t know how (I get that you told me how you did it but since you’re still learning, and don’t have someone there to help show you how I don’t know if your results are reliable) you’re testing them so I can’t say if they’re good or bad. Those transistors are really cheap though so if you want to replace them I think even RadioShack has them, they’re so common.
Don't know where it states that...

https://www.fairchildsemi.com/datasheets/SS/SS8050.pdf

And I tested them as I said... I put the probes on pole 1&2(base and emitter) then switched the probes, and I got a reading both times.


2:17
 
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dstroy

Well-Known Member
I don’t really understand what the transistor does necessarily. I’m just trying to find a component that tests wrong/bad.
A transistor is an electronic switch, that can operate very quickly in most cases. They are ubiquitous.

Don't know where it states that...

https://www.fairchildsemi.com/datasheets/SS/SS8050.pdf

And I tested them as I said... I put the probes on pole 1&2(base and emitter) then switched the probes, and I got a reading both times.
bjt are distinct from fet in how they operate.

It says it right at the top, npn, which is a type of bjt.
 

dstroy

Well-Known Member
Don't know where it states that...

https://www.fairchildsemi.com/datasheets/SS/SS8050.pdf

And I tested them as I said... I put the probes on pole 1&2(base and emitter) then switched the probes, and I got a reading both times.


2:17

Now, when you were testing them, were they in situ?

Because if you didn't desolder them to test them then that can sometimes (depending on the other components in the circuit) greatly affect the outcome of the test. Same goes for the majority of tests when determining whether a component is bad or not.

Troubleshooting components is slightly different than troubleshooting a system (or a circuit). Same principles, differing methods depending on the component.

In this case, we already know what is wrong with the system, and now we are trying to find what component is broken. What you really need is to trace back from the BASE pin of the transistor to the microcontroller and make sure that the microcontroller is attempting to control the relay for the compressor/fan as intended. This is assuming that the circuit design is conventional and uses the base pin for control in a way I am familiar with. I don't know if the circuit design is conventional or not because I don't have access to the schematic, nor do I have access to clear shots of the PCB front and back which is what I would need.
 

Airwalker16

Well-Known Member
Now, when you were testing them, were they in situ?

Because if you didn't desolder them to test them then that can sometimes (depending on the other components in the circuit) greatly affect the outcome of the test. Same goes for the majority of tests when determining whether a component is bad or not.

Troubleshooting components is slightly different than troubleshooting a system (or a circuit). Same principles, differing methods depending on the component.

In this case, we already know what is wrong with the system, and now we are trying to find what component is broken. What you really need is to trace back from the BASE pin of the transistor to the microcontroller and make sure that the microcontroller is attempting to control the relay for the compressor/fan as intended. This is assuming that the circuit design is conventional and uses the base pin for control in a way I am familiar with. I don't know if the circuit design is conventional or not because I don't have access to the schematic, nor do I have access to clear shots of the PCB front and back which is what I would need.
I might have to just unsolder the damn thing. I’m just terrified of not being able to put it back together. Apart is easy...

Yes I tested the transistors while they were on the board still. But you see what I mean by what that video says at 2:17? Mine show a reading no matter which way I Put the probes
 
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