Hi Everyone,
I have on the bench a Yaesu FT-840 that quit transmitting. I am assuming that the owner did not open it up and change anything. I had found the voltage regulator section baked because of the 8.2 ohm resistor and I replaced/upgraded all resistors and replaced all of the caps in that section. I also replaced the 2 regulators and I now have good voltage in that section. This is a very well documented issue and can be seen on Mikes Radio YT channel. After the repair the radio still does not transmit. I then re-flowed the boards (also seen on Mikes YT channel), No transmit. This is a modular radio as many ham radios are. The service manual I downloaded does not show voltages on the schematics so I am unsure what the best process would be. I was thinking that I could test the transmit at the coax transmit jumper to the amp section. What should I expect to see? When I hook the scope up I get nothing. Any help would be appreciated!! I really want to get this back to the owner if possible.
Thanks as always!!
I have on the bench a Yaesu FT-840 that quit transmitting. I am assuming that the owner did not open it up and change anything. I had found the voltage regulator section baked because of the 8.2 ohm resistor and I replaced/upgraded all resistors and replaced all of the caps in that section. I also replaced the 2 regulators and I now have good voltage in that section. This is a very well documented issue and can be seen on Mikes Radio YT channel. After the repair the radio still does not transmit. I then re-flowed the boards (also seen on Mikes YT channel), No transmit. This is a modular radio as many ham radios are. The service manual I downloaded does not show voltages on the schematics so I am unsure what the best process would be. I was thinking that I could test the transmit at the coax transmit jumper to the amp section. What should I expect to see? When I hook the scope up I get nothing. Any help would be appreciated!! I really want to get this back to the owner if possible.
Thanks as always!!