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 Post subject: Re: Transistor types
PostPosted: Jan Sat 07, 2017 7:16 pm 
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In addition to the notes on the board, you can ID the leads on a transistor by looking at the data sheet.

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 Post subject: Re: Transistor types
PostPosted: Jan Sat 07, 2017 8:48 pm 
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There 2n406 rca I believe. . I just wanted to make sure I have the collector identified.
Thanks

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 Post subject: Re: Transistor types
PostPosted: Jan Sat 07, 2017 9:49 pm 
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Eickerman wrote:

I am not aware of any transistors that used a red mark to indicate the collector, but I suppose it is possible.

Oh Curtis, you're jivin', right?

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 12:14 am 
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And the answer is? Lol

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 1:07 am 
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I've never seen transistors with the collector...or anything...defined by a dot of paint. Also, you have to be pretty far down the final glide slope to even know what is a CK722.....;)

"And the answer is"-----what's the question? 2N406?.....did you look it up?

2N406:
http://alltransistors.com/pdfview.php?d ... &dire=_rca

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 1:33 am 
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pixellany wrote:
I've never seen transistors with the collector...or anything...defined by a dot of paint.


The Russian germanium types I got (100 for $25!) have a paint dot, since the leads are otherwise in a straight line and evenly spaced.

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 1:41 am 
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fifties wrote:
Oh Curtis, you're jivin', right?
Nope, never dealt with a CK722. Did deal with a few 2N107's and they didn't do that, and a lot of the round cylinder types that you often find in these transistor radios. Never had to look for a red marking that I can remember.

Now that we know the number here is the data sheet...
Attachment:
2N406.jpg
2N406.jpg [ 103.44 KiB | Viewed 1303 times ]
I always worked from the Emitter-Base-Collector triangle arrangement. Apparently there is a red dot that I did not depend upon.

Curtis Eickerman

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Last edited by Eickerman on Jan Sun 08, 2017 1:52 am, edited 3 times in total.

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 1:48 am 
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Collectors on a transistor defined by a drop of paint??? That's just crazy talk! :lol: :lol: :lol:

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 1:51 am 
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Yes mark I checked the data sheet, still it's not crystal clear, I replaced the transistors x6 answer x7 . Checked the resistance the common point between x6 and x7 and curt was right it rose to over several meg ohm. Voltages are close to what is specified on the schematic now for x6 and x7, will check them all tomorrow. Still not working. I suspect x8.

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 3:42 am 
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devildog63 wrote:
Yes mark I checked the data sheet, still it's not crystal clear, I replaced the transistors x6 answer x7 . Checked the resistance the common point between x6 and x7 and curt was right it rose to over several meg ohm. Voltages are close to what is specified on the schematic now for x6 and x7, will check them all tomorrow. Still not working. I suspect x8.


I take it that the output stage now generates audio (hum test or signal injection)?

Brett


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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 4:21 am 
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Nothing coming out of speaker. Just a click when I turn it on. How do we test if?

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 5:15 am 
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devildog63 wrote:
Nothing coming out of speaker. Just a click when I turn it on. How do we test if?


Turn the radio on, and touch the tip of a soldering iron to the center terminal of the volume control, or connect an iPod or similar to the same point and ground. Should get a hum or buzz in the first case and whatever the iPod is putting it out in the other. If nothing happens, you need to work your way up the path and determine where the other problems are.

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 2:56 pm 
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I missed something.....how did you get to a 2n406?----is that a sub for the original?

With respect to identifying the leads--- what was the issue in using the data sheet?

Trouble-shooting: are all the DC voltages right now? I would not bother with signal testing if the voltages are not right.
<<edit...I see you said x6 and x7 voltages are OK.>>

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Last edited by pixellany on Jan Sun 08, 2017 3:02 pm, edited 1 time in total.

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 3:01 pm 
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devildog63 wrote:
Yes mark I checked the data sheet, still it's not crystal clear, I replaced the transistors x6 answer x7 . Checked the resistance the common point between x6 and x7 and curt was right it rose to over several meg ohm. Voltages are close to what is specified on the schematic now for x6 and x7, will check them all tomorrow. Still not working. I suspect x8.

What is X8?

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 4:41 pm 
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X8 is the diode, 2n406 is a nte102 EQ. I mentioned X8 earlier that I was getting no audio out of it. And I was told to work on the audio output. I'm going to recheck all my voltages now and post them. X7 and X6 have been replaced.

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 5:21 pm 
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Ok new voltage readings. I did try the soldering iron on center point of volume control and got a very slight hum with volume max.

X1 base -8.3 . Collector -8.5. Emitter -5.6

X2 base -8.2 . Collector -8.4 . Emitter -2.7

X3 base -8.1. Collector -7.3 . Emitter -3.8

X4 base -7.0. Collector - 7.2. Emitter 0

X5 base -7.1. Collector -7.2. Emitter -1.1

X6 base -8.0. Collector -8.3. Emitter -4.6

X7 base -4.2 . Collector -4.6. Emitter 0

These measurments are with a fresh battery that measured 9.1VDC

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 8:52 pm 
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I transferred your voltage readings to the schematic. Needless to say, there is a problem. You will note this by comparing your readings in RED with the voltages recorded on the schematic. I am somewhat at a loss to figure out how you are getting the readings you are getting. The best answer I can come up with is that both your battery and meter are connected backward. If that is the case the negative of your battery is actually connected to Ground, but your meter is set up or hooked up to read positive voltages as negative. Remember I could always be wrong about this.
Attachment:
Voltages.jpg
Voltages.jpg [ 138.92 KiB | Viewed 1251 times ]
I am not suggesting you change anything, but you need to be absolutely sure the Positive side of your battery is going to the switch and from the switch to ground. Do not trust the color of any wire to tell you anything. Check with an Ohm meter the connections all the way from the positive terminal of the battery all the way to ground (make sure the battery is disconnected and check from the battery clip terminal all the way to ground which should be zero Ohms with the switch in the ON position).

When things are correct the Base voltage of each transistor will be approximately 0.2V to 0.3V more negative than the Emitter (your readings are showing these to be many volts which is physically impossible).

Until we figure out how you are getting the voltage readings you are getting there is not much more we can do.

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Last edited by Eickerman on Jan Sun 08, 2017 9:08 pm, edited 1 time in total.

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 9:08 pm 
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devildog63 wrote:
X6 base -8.0. Collector -8.3. Emitter -4.6

X7 base -4.2 . Collector -4.6. Emitter 0

These measurments are with a fresh battery that measured 9.1VDC


Wow, I don't even know how that could be. It's not close. It acts like R19 or the trace going to it is open. Did you record the resistance measurements when the transistors were out?

Brett


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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 9:22 pm 
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I don't believe this but the old battery connector was replaced by my father back in 1973. He has this crossed. I installed a new battery snap and it works like a champ. Thanks Curtis for that comment , it's something I should not have taken for granted but I did. That's the very last time I don't check all the easy things First! Again thanks curtis!!!!

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 Post subject: Re: Transistor types
PostPosted: Jan Sun 08, 2017 9:23 pm 
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Thanks for everybody's help sorry I missed such a simple thing, it won't happen again!!

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