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DreadPirate 2nd June 2006 02:26 PM

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?

clem_o 3rd June 2006 08:51 AM

Should be ok to do that...

Good luck!


jblmar 30th June 2006 09:30 PM

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


anatech 1st July 2006 01:09 AM

Hi Ron,

Not a bad idea, but at times an intermittent transistor can be 'shocked' into working.
If the circuit now works after the sub., discard the other transistor and replace it. Even if the other circuit works.


clem_o 1st July 2006 10:03 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...



anatech 2nd July 2006 02:54 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!


jblmar 7th July 2006 03:32 PM

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


anatech 7th July 2006 04:43 PM

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

How about you?


jblmar 7th July 2006 05:12 PM

Doin' fine.


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