Hi, Enjoy your channel. Especially the extended IC746PRO repair, my favorite radio. I have come to appreciate using an SDR while working stations. I would like to tap the first IF to share the working antenna. Is this a good idea, and can it be done without ruining audio of radio. Also, would the point of the tap be grounded to protect the SDR? I think it would make a good video. Thanks, Bill KD8HSK
So: it seems to me unlikely that a couple 1 ohm resistors would magically become 100ohms - if I understood correctly. My bet is you are seeing a production error. 100 ohms inserted instead of 1ohm. Also: those transistors need to come out to test properly.
Hello IMSAI, did you noticed that the L7 LR -384 pre-driver output transformer is misplaced in the schematics? L8 Feed biasing voltage to the drivers at center tap of the secondary winding, but it is on the opposite direction.
Looking at the circuit, I don't see a path for those resistors to get DC power, except if the tranies are broken - but you measured them ok. If they really are (as it's hard to measure in-circuit), then RF power destroyed those resistors. In that case, the same current was flowing throught the 1 ohm resistors that became 100Ohm, but that is also strange, as they would limit that current. While "working", what were the DC and AC levels on the bases of the transistors? How unbalanced was the push-pull stage?
Come on you already know because 5of8. Your spoon feeding us slowly. We can't take it.... more please. Short from collector to the base. You didn't give any voltage or scope measurements. One or both of the pre-drivers. Need to to replace in a match set... if you can get them. Obsolete ?
Your camera skills are legendary.
Thanks
Hi, Enjoy your channel. Especially the extended IC746PRO repair, my favorite radio. I have come to appreciate using an SDR while working stations. I would like to tap the first IF to share the working antenna. Is this a good idea, and can it be done without ruining audio of radio. Also, would the point of the tap be grounded to protect the SDR? I think it would make a good video. Thanks, Bill KD8HSK
So: it seems to me unlikely that a couple 1 ohm resistors would magically become 100ohms - if I understood correctly. My bet is you are seeing a production error. 100 ohms inserted instead of 1ohm. Also: those transistors need to come out to test properly.
Hello IMSAI, did you noticed that the L7 LR -384 pre-driver output transformer is misplaced in the schematics? L8 Feed biasing voltage to the drivers at center tap of the secondary winding, but it is on the opposite direction.
From DC point transistors are in parallel and can't be properly tested.
It seems that they should be removed and tested out of the circuit.
you are correct
bagus penjelasannya sangat detail.
nice detailed explanation
Wow! This is a failure that I never saw mentioned in the FAQ.
Silly question, but did you change the open 47 ohm resistor ?
yes, both 47 ohms, I replaced with 51 ohms
@@IMSAIGuy Yeah, sorry. I knew it was a silly question. Ha ha.
Looking at the circuit, I don't see a path for those resistors to get DC power, except if the tranies are broken - but you measured them ok. If they really are (as it's hard to measure in-circuit), then RF power destroyed those resistors. In that case, the same current was flowing throught the 1 ohm resistors that became 100Ohm, but that is also strange, as they would limit that current. While "working", what were the DC and AC levels on the bases of the transistors? How unbalanced was the push-pull stage?
the diode check function of a voltmeter gets tricked with low value resistance. Next video I will take out the transistors
just like the last video, the points you were probing were off camera. very frustrating.
Come on you already know because 5of8. Your spoon feeding us slowly. We can't take it.... more please. Short from collector to the base. You didn't give any voltage or scope measurements. One or both of the pre-drivers. Need to to replace in a match set... if you can get them. Obsolete ?