On 08/07/2020 15:04, Vince Fiscus, KB7ADL via AMSAT-BB wrote:

Hi All,

I walked into the shack about a month ago and smelled something really hot like the smell from a hot resistor.  Turned off all the equipment waited a while then turned everything back on.

The FT-736 didn't come back on, so I assumed the power supply, as this is a common problem with the rigs as they get older.

Bought a repair replacement kit for the electrolytic caps in the power supply, which is normally the problem. They get baked and fail.

Got the power supply out last night to do the repairs and I discovered it was the SCR in the power supply that had totally burned up. Weird.

Does anyone here have or know a Digi-key or Mouser part number for the SCR or an equivalent compatible part? It labeled SCR21 on P.C. board.

Vince, Please either post results here or privately to me about fixing your 736 power supply.  I am in the same position except that I have not done the caps & resistors replacements yet.  Therefore, I am in an information sponge mode as I do want to get mine working again. I expect to do the caps and resistors replacement.

According to the writeup I found for repairing the power supply, there is a schematic from DL7VHF that shows the SCR that appears to be part of an over voltage crowbar circuit to be a part 6P4M.  When I did a Google search for that, there were lots of hits.  This page may be very useful.

https://category.alldatasheet.com/index.jsp?components=scr%25206P4M

Good luck with your repair...