[Yaesu] FT-840 Flashing Display

[Eric Lemmon]

I found the part numbers in my FT-840 Service Manual.  Q2801/Q2901 is P/N
HA7805P, and Q2802/Q2902 is P/N L7809.  These appear to be garden-variety 78xx
voltage regulator ICs in a TO220 case, available at your local Radio Shack.
Both of these regulators should be installed with heat-sink compound between the
tabs and the chassis for proper heat transfer.

73, Eric Lemmon WB6FLY

Thomas Giella KN4LF wrote:

> ...The flashing display problem means a bad regulator transistor(s).  If you
> remove the covers and flip the rig upside down you will see two transistors
> bolted to the metal chassis near the TCXO. These transistors run very hot and
> the act of bolting the transistors to the chassis is insufficient for proper
> heat
> sinking and therefore they fail prematurely... I don't remember the transistor
> part number but I bought mine at RF Parts.