I started looking at a FT-620B that I have had for years. It had been in storage for around 8 years, and when it was last used everything worked fine. After powering up I found that while the receiver worked great, there is no output. I tested it in all modes, and all band switch positions with no luck. The initial steps I took were to clean all board connectors and the band switch. I also made sure all of the board mounting screws were tight. The relays are working fine, and the removable one came out of a working radio, so I know that is good. The main problem is that it appears there is no service manual for this radio anywhere to be found. I can find the owners manual with instructions for alignment, but there is very little information regarding test points in the radio for checking things like voltage, etc. Would like to get this one back on the air if possible, but not even sure where to start.
You will have to pay for the service manual from these folks, but that would be a good place to start, I reckon. http://www.manualsparadise.com/service-repair-manuals/Yaesu/FT-620B-FT620B/RWSPFM-25388181-1
I have an FT-620B manual that I think I downloaded from the Fox-Tango website. A quick look shows it has schematics and parts list plus all the other typical 70's Yaesu manual stuff. Someone has written on the schematic before it was scanned that TP408, the driver output to the PA booster module should show 2v p-p. Might be a start. I can upload the manual somewhere if you need a copy. Martin, HS0ZED Reminds me I need to ask a question about low power on an FT-901
