Here is another of Tony G0MQGs findings when servicing a popular radio.
If you like it and would like to see more, let him know!
FT1000 repair
Recently I acquired a Yaesu Ft1000 with a fault that neither the main receiver or the transmitter would work but the sub receiver was ok ( I’ve no problem buying faulty gear as long as I’m told and it’s reflected in the price which it was with this one )
I suspected a power supply problem so i studied the schematic to see what internal supplies there were.
Onto the bench it went and off came the top cover. I plugged in and switched on, the display powered up normally as did the sub receiver when selected.
A check of the +30 volt supply showed this was ok so I checked the other supplies and found the - 9 volt supply was in fact - 17 volts.
This is derived from a 7909 voltage regulator so it seemed this had failed. I removed it from the radio and fed it from a bench supply set at 24 volts, sure enough - 17 volts output.
I didn’t have a 7909 but did have a 7905 ( - 5 volts) so as a temporary solution i fitted this with a 3.9 volt zener diode in series with the common pin to give 8.9 volts.
Success! The radio now worked fine so I ordered some 7909 regulators and once arrived, fitted one which got the radio working.
I then done the “las Vegas” test to see what rom version was fitted, needs to be version 6 to have reliable “cat” facilities so I understand. (Anyone who has owned an FT1000 will probably know what the “las Vegas” test is.)
To perform this test press and hold the 1.5mhz and 7mhz band selecting buttons while turning the radio on, the radio will then go through a test procedure for the display and then display the word “YAESU” and the rom version.
Mine had version 5 so I programmed a 27256 eprom with version 6 firmware to update the rom.
The radio now works fine and is now in my shack as my main HF rig at a cost to me of much less than it’s value now that it works ok and only cost a few pounds to fix it
Tony g0mqg
