I have an old Midland 202m that has no TX,when I received it it had no TX or RX,I replaced the audio ic and now have RX and the PA is working,I also replaced the driver and final which were also bad,I can hear a little TX in another receiver,sounds like it,s only working on the driver or predriver or possible the oscillator stage.I don,t see any other burnt parts.I know this is an old radio but i would still like to get running anyway.the only # i can see is on the board is 4010087?
Tnx Bob
Midland 202m
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captian_radio
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ramblingman
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i am not firmilar with this radio,,but with alot of the older type radios..they have rf chokes,in seriers..i have found this to be the trouble on alot i worked on...exscpecally when youve had parts shorting out ,,like finals,,audio chips....these chokes will look like big resistors,with fine copper wire wrapped around the outside of them...these should read full scale on your v.o.m,, if they read open,this is your trouble..on some of the older rigs,,they may have 2 or 3 of these
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captian_radio
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m202
Well I did disable the driver and still getting the same amount of output,with the driver still in place it does get a bit warm after a long key down.Checked the chokes and they are fine, it seems that the signal is not making it as far as the driver so could it be an issue somewhere in the pre driver stage if it does indeed have one.The original final was blown to bits and I have checked the parts around it they seem fine.If it has a pre driver stage I,m not sure which TR to check out,I did fine a schematic for it but the quality is very blurry and hard to read.If I place a probe on certain parts with it keyed I can see a much stronger signal on the other radio,seems to me that something is not turning on the driver or final,could be a switching Tr,what do you think?
Bob
Bob
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ramblingman
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captian_radio
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M202
Well I have the M202 going again,tnx to those who offered advise,such as Rick in a pm and ramblingman,I over looked a small 3.3 ohm resistor which was connecting the driver output to the final,it looked ok but it was open I replaced it and bingo up and running.
Bob
Bob