Hi everyone, is there a Yaesu rig user in the house?
I just got this beat up FT-2900R for cheap. It had a bunch of problems that I managed to fix, but one remains without a solution in sight.
For now, almost everything works normally, except for the fact it’s showing considerably less voltage than the supply. During the start-up, it shows the voltage exactly as supplied only for a brief moment (long enough for me to read it) before droping around 3-4 volts. As the result, my transmit power gets cut-off due to the low voltage.
I even tried changing all the thru-hole caps, to no avail.
Not sure if this matters, but I’m powering it with a Meanwell style SMPS.
Anyone familiar with this issue?
Have you verified it isn’t a power supply problem? If you have a battery handy, that’d be an easy way to check. I’d also measure the voltage at the radio’s power port.
I’m not very familiar with yaesu rigs, so I don’t have any ideas on the radio side.
Good luck
I’d guess that either your supply can’t deliver the 15 Amps the radio needs or the radios internal voltage regulator has a problem.
The power supply is rated for 360 watt, but who knows, it is a cheap chinese product after all.
Update: After inspecting the components’ voltages across the circuit and cross-checking it with the service manual, I found one of the transistors, marked Q1008 in the diagram, might be out of spec. The component should’ve been 2SJ615. Who knows what the phony seller did to it, but it was outputing well below the specified 13.5-13.8V (yes, I made sure the input was correct).
Update: The correct part has arrived. After replacing it, no more voltage drop!
Update: I accidentally shorted some component’s pins and the it failed to deliver the specified power once again. Guess now I know what happened to the old component I replaced. Luckily I have a spare.
