help needed with old detector

[dbanner]

Give it a rest for time being?

[keith777]

Hi again dabanner.

i changed that part but still no joy. the machine is just the same.

[dbanner]

C2076. Remove this one. Post a pic of the one you chose, then i will show you how to orient legs to put on new board. In fact i will show you now. refer to pic

[keith777]

here is some.


C711
6ZF

A733
A0103

C2296
7X3C

A999
9XF

CI675
M2X0

C1342
B
0K 2

N13T1
01

C945
02X8A

C2076
D 89

TA78L
009P .OB

[dbanner]

Perfect! One of those should work. just record the numbers on a few of them and post. I''ll check to see which one will work.

[keith777]

i know there is loads of the first image one's. (index) with different numbers on. i have two old CB Radio boards that have a lot of then on the boards. i think they mainly start with CN on them.

[dbanner]

to92 is just the package type, this number is not on transistor. Look for these types, if you find one, post the number on it. I will then tell you if you have a winner.

[keith777]

Hi again dabanner.

i can not see any round shaped one's on any of the boards that i have.
what do the rectangular ones look like and do they have to have TO92M on them.

[dbanner]

Any old NPN driver transistor will work for your purpose. Salvage one from junk board. IT DOES NOT HAVE TO LOOK THE SAME ROUND SHAPE, IT COULD BE RECTANGULAR SHAPE(TO92M PACKAGE). Take note of the number and check online datasheet to see if its NPN.

[dbanner]

This is called a tab and indicates position of emitter leg of transistor. Well you have found the bad guy! Now you must find a replacement. 2N3053 NPN AF(audio Frequency) Driver. You said earlier in thread you have junk boards lying around? You might be able to salvage an appropriate substitute transistor.

[chevesne]

Emitter indicator.

[keith777]

the number on it is. 2n 3053
what is the small brass bar on the transistor. it looks adjustable. pic bellow.

[dbanner]

Actually, if its a darlington transistor, it may not be bad at all. you'll have to cross reference the number to see for sure.

[keith777]

yes i cut the track with a blade like you suggested. the speaker kept crackling when i was doing the test. don't know if that is normal or not.
i will go and see if i can find the numbers for you now.

[dbanner]

You have meter setup correctly. Did you remove base leg from circuit? If so, then this transistor checks BAD!! Since this is transistor which drives the speaker, I think we have possibly found the problem. Look at transistor and tell me the number on it.