Subbing Transistors Within A Unit

DreadPirate · 2nd June 2006, 01:26 PM

I am working on a receiver that has the same type of small signal transistor in the AM and MPX sections. The MPX section transistor is suspect, I am going to pull it and if I cannot determine for sure that it is defective, I would like to sub one from the AM. Speaking generally, can just about any transistor be pulled from an AM section and place left vacant without any ill effect on the AM section when I turn on to test the FM section?

clem_o · 3rd June 2006, 07:51 AM

Should be ok to do that...

Good luck!

Cheers

jblmar · 30th June 2006, 08:30 PM

Not a bad idea, but at times an intermittent transistor can be 'shocked' into working. Desoldering can produce just that result.

Ron

anatech · 1st July 2006, 12:09 AM

Hi Ron,

Quote:

Not a bad idea, but at times an intermittent transistor can be 'shocked' into working.

Yes.
If the circuit now works after the sub., discard the other transistor and replace it. Even if the other circuit works.

-Chris

clem_o · 1st July 2006, 09:03 AM

Not only on transistors - ICs too. Sometimes, the wire-bond (to silicon pad) is soooo marginal that a little thermal causes it to work (or not). Other times, the internal wires marginally touch each other (usually due to incorrect epoxy plastic flow during packaging). You can get very strange effects from that...

Uh, so what am I trying to say - Chris' advice is good - throw away the sub'd unit, particularly if it's inexpensive...

Cheers!

Clem

anatech · 2nd July 2006, 01:54 AM

Hi Clem,
Excellent addition. IC's are certainly not exempt.

"If in doubt, yank it out!" Make sure it hits the garbage can too!

-Chris

jblmar · 7th July 2006, 02:32 PM

How are you, Chris. Haven't be in contact with you in a while.

Ron

anatech · 7th July 2006, 03:43 PM

Hi Ron,
Not too bad. I'm still on the right side of the grass.

How about you?

-Chris

jblmar · 7th July 2006, 04:12 PM

Doin' fine.
Thanks

Ron

2nd June 2006, 01:26 PM	#1
DreadPirate diyAudio Member Join Date: Jan 2006 Location: Northern Virginia, USA	Subbing Transistors Within A Unit I am working on a receiver that has the same type of small signal transistor in the AM and MPX sections. The MPX section transistor is suspect, I am going to pull it and if I cannot determine for sure that it is defective, I would like to sub one from the AM. Speaking generally, can just about any transistor be pulled from an AM section and place left vacant without any ill effect on the AM section when I turn on to test the FM section?

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3rd June 2006, 07:51 AM	#2
clem_o diyAudio Member Join Date: Jun 2005 Location: Manila	Should be ok to do that... Good luck! Cheers

30th June 2006, 08:30 PM	#3
jblmar diyAudio Member Join Date: Dec 2005 Location: Brooklyn, New York	Not a bad idea, but at times an intermittent transistor can be 'shocked' into working. Desoldering can produce just that result. Ron

1st July 2006, 09:03 AM	#5
clem_o diyAudio Member Join Date: Jun 2005 Location: Manila	Not only on transistors - ICs too. Sometimes, the wire-bond (to silicon pad) is soooo marginal that a little thermal causes it to work (or not). Other times, the internal wires marginally touch each other (usually due to incorrect epoxy plastic flow during packaging). You can get very strange effects from that... Uh, so what am I trying to say - Chris' advice is good - throw away the sub'd unit, particularly if it's inexpensive... Cheers! Clem

2nd July 2006, 01:54 AM	#6
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Clem, Excellent addition. IC's are certainly not exempt. "If in doubt, yank it out!" Make sure it hits the garbage can too! -Chris

7th July 2006, 02:32 PM	#7
jblmar diyAudio Member Join Date: Dec 2005 Location: Brooklyn, New York	How are you, Chris. Haven't be in contact with you in a while. Ron

7th July 2006, 03:43 PM	#8
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Ron, Not too bad. I'm still on the right side of the grass. How about you? -Chris

7th July 2006, 04:12 PM	#9
jblmar diyAudio Member Join Date: Dec 2005 Location: Brooklyn, New York	Doin' fine. Thanks Ron

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