05-10-2013, 01:56 PM
OK.
Do you know how to check a transistor?
If not, here's how:
1. Take an ANALOG Ohmmeter.
2. Set it to Ohms, x1 range.
3.
For an NPN transistor:
Put a positive lead to the base, and touch the emitter and collector with the negative. It should conduct. Reverse the leads. Do the same. There should be no conductivity at all. Any conductivity means leakage and the transistor is bad.
For a PNP transistor: same procedure, only leads are reversed. Negative to the base conducts, positive - does not.
4. For any transistor: put one lead to emitter and another to collector. There should be no conductivity. Reverse leads, same thing.
Transistors rarely lose their H21E (Beta) so as long as the integrity test above is good, your transistor is good.
Now that you know that:
Take your schematic, and start checking transistors starting from Q3 and back.
Question: do you have a scope?
PS> Eric, I can guide you through it, but you need to have a basic equipment. A scope would make it easy.
Do you know how to check a transistor?
If not, here's how:
1. Take an ANALOG Ohmmeter.
2. Set it to Ohms, x1 range.
3.
For an NPN transistor:
Put a positive lead to the base, and touch the emitter and collector with the negative. It should conduct. Reverse the leads. Do the same. There should be no conductivity at all. Any conductivity means leakage and the transistor is bad.
For a PNP transistor: same procedure, only leads are reversed. Negative to the base conducts, positive - does not.
4. For any transistor: put one lead to emitter and another to collector. There should be no conductivity. Reverse leads, same thing.
Transistors rarely lose their H21E (Beta) so as long as the integrity test above is good, your transistor is good.
Now that you know that:
Take your schematic, and start checking transistors starting from Q3 and back.
Question: do you have a scope?
PS> Eric, I can guide you through it, but you need to have a basic equipment. A scope would make it easy.
