Flex-5000a SWR bridge mod??

nkhdk

Hi,

Just got this radio back in the workshop, fixed the IEE1394 ports (new chip) a while ago and it worked well after that.

Now we have low PA output on all bands HF/6M, ~30W only.
ATU option installed and seems to work.
Selftest gives random errors at PA/BIAS, not giving sense.

My feeling is that the root couse is in the the SWR detection and I've dismounted the HPA100 board (it's rev. G btw.).
To my great concern I find black oxidation on the PA finals ground connections and a "mysterious" modification at the SWR detection circuit.

A diode is connected betw. D3 (R15 end) and GND...?

The oxidation we can deal with (is it normal?), but the mod is not documented anywhere I can find.
The rig has been working with the mod, but the soldering looks NOT like something I'd trust at all, hence not something Flex accredited..?
Does anyone know about some un/documented mods in this area?

I don't know the history of the unit, this guy bought it second hand...

Thanks in advance!

Vy 73 de OZ8AFH, Axel