Galaxy Saturn Turbo low transmit power (Amp board issue)

Hi Everyone,
Thanks to some amazing help on here with voltage issues this radio had I was able to repair the radio by installing a switching power supply. Once the new power supply was installed I performed some testing at the bench and the radio did function well. I did have decent receive audio from my signal generator and the radio was transmitting at high wattage into the dummy load. I did not perform an alignment yet. Once some basic testing was complete I connected the radio to my antenna and was able to make some contacts on 38lsb. I had the power set at about 50%. The radio was pushing a little over 100 watts (non-PEP). I even made 2 to Florida as skip was running. After about 5 minute of use the power dropped to a couple watts and the amp board was emitting some odor so I shut it off. After some testing the amp board is not working. I bypassed the amp by connecting the internal coax from the main board to the swr bridge and the power out is the same. That means that when the amp board is in line and the radio is transmitting the power coming of the main board is the only power leaving the radio and......the odor is still emitting from the amp board during transmit. No smoke yet. I cannot find a schematic for the amp board so I am even more lost. One thing to note, the radio has not worked for over a year so the baseline of its performance is not great. Also, on the amp board is a variable resistor and it was cranked to it full position. I have no idea what the adjustment is for and the owner of the radio said that he was not sure if anyone turned it or not. I am wondering if it is a bias adjustment for the amp or a power regulator. Either way the board is not working and I could use some help.

Thanks in advance!!!

sonoma said:

take a look at the final section of this radio and compare it to what you have. may be the same.

http://www.cbtricks.com/radios/rci/rci_2985dx/graphics/rci_2985dx_95dx_sm.pdf

Click to expand...

That was close. The parts layout for the amp board was similar but not exact. Also, there was no schematic for the amp. Thanks for trying!!!!!

Hey Nomad,
I was able to fix this amp board. The board is a pre Y2K board with 2 white pills labeled 2990. The issue ended up being the mini coax connector soldered in the board that is the output of the amp board. While I cannot explain why it was smelling or what the exact issue was I did find that it was the location of the issue. I removed the coax socket from the board, cut the coax plug from the mini coax and soldered the coax directly to the board. WALA, the amp is now putting out full power. I still have some questions about the board and I would love to know what the variable resistor is for but for now it is working.

Thanks again for your help!!!!

The radio now has a new power supply and rock solid coax connections. When the owner is ready and can afford it a recap will be the next step.