Yaesu 101F

Discussion in '"Boat Anchor" & Classic Equipment' started by KC9SGI, Jul 5, 2020.

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  1. KC9SGI

    KC9SGI Ham Member QRZ Page

    I have a yaesu 101F keeps burning up R16 on PB-134A (Regualtor/calibration board). I have checked the diodes on rectifier board,all good. I have removed the tubes, still smokes the resistor. Any ideas would be greatly appreciated.
     
  2. W1NB

    W1NB XML Subscriber QRZ Page

    What value resistor are you putting in? The 1314A is not original to the F model. It should be a 1574A. R16 is a different value (1.5k) and in a different circuit (bias) on the 1314A compared to 33k in the crystal calibrator on the 1574A.

    If it is R16 on the 1314A board, check to see if D3 Is shorted.
     
  3. KC9SGI

    KC9SGI Ham Member QRZ Page

    I stand to be corrected. the board is a 1574B . I was getting the value off of the schematic. you are saying that is should be a 33K ohm resistor?
     
  4. KC9SGI

    KC9SGI Ham Member QRZ Page

    I looked it up. My bad it is r17 4.7K resistor on the 1547 board.
     
  5. W1NB

    W1NB XML Subscriber QRZ Page

    R17 on the 1547 regulator board is a 10k ohm resistor. The only 4.7k n that board is R1.
     
  6. KC9SGI

    KC9SGI Ham Member QRZ Page

    yes this resistor is a 4.7k in the bias circuit. This resistor is located on the bottom side of the 10k ohm resistor, it is going to ground. The junction of the 10k and 4.7k ohm resistors goes to pin 3 of the board. The 4.7k ohm resistor will burn up as soon as you turn the radio on.
     
  7. W1NB

    W1NB XML Subscriber QRZ Page

    what are you measuring for DC voltage on pins 2, 3 and 4? Please state the polarity as well as the number.
     
  8. G3YRO

    G3YRO Ham Member QRZ Page

    That really doesn't make sense, as Pin 3 is just the CW Keying line, and is connected to ground on Transmit on all modes except CW by the Mode switch (so R17 is shorted out) . . . and even if other components around it had failed, then other higher value resistors should limit the current through that resistor.

    You haven't done something silly, like replace the Main Relay with the WRONG type? (Common relays that will fit are actually wired incorrectly, and would cause all kinds of problems!)

    If not, try unplugging all 3 Valves, to eliminate an internal Valve short causing a problem. (like feeding the Screen Grid Voltage back down the Control Grid)

    Roger G3YRO
     
    Last edited: Jul 12, 2020
    KD2ACO likes this.
  9. G3YRO

    G3YRO Ham Member QRZ Page

    Sorry - I meant R1 is shorted out (they call it R17 on all the earlier FT101 boards . . . for some reason they have re-numbered it on the FT101F Board !)

    Roger G3YRO
     
  10. KC9SGI

    KC9SGI Ham Member QRZ Page

    here are the voltage readings. 1 thru 5 . 1=o,2=29v, 3= 167.5 v, 4=137v, 5= -173.8
     

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