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Rxnapier
New member
Username: Rxnapier

Post Number: 3
Registered: 1-2012
Posted on Wednesday, January 04, 2012 - 10:50 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

i have a sears roadtalker 40 ssb model 934 38270700.
it was a hell of a radio untill it just stopped transmitting...i push the mic and nothing happens, the receive doesnt even cut out.
at first i thought it had to be the mic cord or plug but after cking it out i found it to be in good condition.
the relay doesnt click or do anything.
i took the plastic cover off the relay and i can manually close it and the radio works like its supposed to.
so the relay isnt getting excited or something.
does anyone know what to look for?
there is a power transistor close by but i dont know if that has anything to do with it.
just thought maybe someone knew what component to check ...maybe a certain resistor or cap
thanks for any info
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392
Intermediate Member
Username: 392

Post Number: 120
Registered: 6-2003
Posted on Thursday, January 05, 2012 - 10:33 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Hey Rxnapier, look at my cherokee 1000 post, same thing blew a final. was an easy fix but it did knock receive and xmit like you described.

hopefully a tech will chime in, there are some good ones here!
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Rxnapier
New member
Username: Rxnapier

Post Number: 5
Registered: 1-2012
Posted on Thursday, January 05, 2012 - 3:40 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

i dont think it could be the finals...cause i can put my finger on the relay and it will key up and work....i actually talked to someone in ohio holding my finger on it.
it just wont work with the mic. and ive tried 2 other mics ...same thing.
i cant see any broken wires or anything..there must be something burned out
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Nitrus
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Username: Nitrus

Post Number: 7
Registered: 12-2011
Posted on Friday, January 06, 2012 - 4:07 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Could it be the coil of the relay or possibly a switching transistor?
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Tech237
Moderator
Username: Tech237

Post Number: 1516
Registered: 4-2004


Posted on Friday, January 06, 2012 - 8:55 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

if you short the appropriate pins on the socket, does the radio switch to transmit?

Did you check teh coil opn the relay to make it is still continuous? Check teh back Diode that should be across the coil - if it is short circuit it will stop the coil froms eeing any voltage, and if it open circuit the back EMF from the relay opeinging may have taken out the switching transistor.
Tech237
N7AUS

God made me an athiest, who are you to question his wisdom?
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Rxnapier
New member
Username: Rxnapier

Post Number: 6
Registered: 1-2012
Posted on Sunday, January 08, 2012 - 12:54 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

ok ill ck all that... iwonder what that transistot was thats clost to there and i did ck to see if i could short the mic pins...no go!
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Tech237
Moderator
Username: Tech237

Post Number: 1517
Registered: 4-2004


Posted on Sunday, January 08, 2012 - 8:41 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

The the relay coil, the diode and oer the switching transistor are the most like culprits.
Tech237
N7AUS

God made me an athiest, who are you to question his wisdom?
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Rxnapier
New member
Username: Rxnapier

Post Number: 7
Registered: 1-2012
Posted on Wednesday, January 18, 2012 - 12:30 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

i have been unable to find the switing transistor for this radio
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Press_man
Intermediate Member
Username: Press_man

Post Number: 368
Registered: 5-2008
Posted on Tuesday, January 24, 2012 - 7:40 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Tech 237 + Rxnapier

I have a Sams 246 on that radio, things closest to relay:
Volts in 13.77
diode on bottom:D-608
ck L-401(L-406)D-404,C-425,C-761,C-428,R-409,R-410

These are the first inline on schematic. I'll look further if this doesn't work.

A friend had one with a dead relay and it was one of the caps.

73
Pressman/KC4ZWM

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