RCI 2950 / RFX 75, NO TX power unless bias board is REMOVED? Also No AM TX power out

[mr_fx]

This has got to be one of the oddest things I have ever seen. I was asked to install an RFX75 into an RCI 2950. Against my better judgement I decided to t

First thing I noticed was that there was I few thing removed from the RFX75;

1.) yellow wire
2.) blue wire
3.) Capacitor # 10
4.) RX Out Coax

So I used these web pages to ID and replace them.

http://www.cbtricks.com/miscellaneo...fx_75/graphics/rfx75_coax_cable_locations.pdf

http://www.cbtricks.com/miscellaneous/accessories/power_band/rfx_75/graphics/rfx75_pcb_layout.pdf

http://www.cbtricks.com/miscellaneous/accessories/power_band/rfx_75/graphics/rfx75_schematic.pdf


From there I installed the RFX 75 according to this walkthrough;

http://www.cbtricks.com/miscellaneo..._75/graphics/rfx75_install_guide_rci_2950.pdf

I even went to the trouble of reconnecting the ALC.

I returned the radio to my friend and a couple days later he called me up saying it had problems.

I took the radio back, and found that it was not putting out ANY power. And that he had added a fan to the back of the RFX75 heatsink.

Well come to find out he had attached the fans 12v+ wire to the collector of one of the old final transistors. I removed that and nothing happened.

I removed the bias board and forgot to hook up my multimeter (to test bias on the driver) and now weirdly enough the radio suddenly put out some power on the watt meter, about 5 watts. This was true on FM, and SSB, but NO dead key or swing on AM

However even with no power out a local could hear me on the air, as could the HF rig in my radio room

I replaced the bias board and it went back to making no power at all (but you could still hear the radio)

So I have a feeling that this is caused by a diode...

 

[mr_fx]

make you guys a deal, you see my brain hurts from staring at this thing, and I don't want to spend too much time on a radio that I am not getting paid to do.

so... $10 via PAYPAL gift, or $8 cash via USPS mail to the first person to help me figure this thing out.

 

[mr_fx]

well I think I need to start by back tracking this for the final's collector and working my way out until I find the problem... it's kinda been a back burner sorta deal, when you are not making any money you don't tend to get to excited about doing work... lol