开云体育

ctrl + shift + ? for shortcuts
© 2025 开云体育
  1. Yaesu-FT-101
  2. Topics

Early FT-101 problems

 

I have an early FT-101 SN below 25000. Problem is it has no 13.5 volts. It keeps blowing D7 and shorting D8. I have replaced them with IN4004's which seems to be what most people use. I have also replaced C6 with a same value ceramic cap. Both 10.5vac lines on the xfrmr are good. The diagram I have shows the 13.5v going to the power jack but does not show where it comes out to the rest of the system. All other voltages at the xfrmr are normal. I suspect there is a short somewhere but I have no idea where to start tracing the 13.5 through the rest of the system. Any help is appreciated.?
 

开云体育

No expert here, but can suggest a few things.

Remove all the boards.

Measure the resistance to ground of the 13.5 vdc line.

If grounded, suspect the Dial Lamps housing shorting.

If all ok then, insert one board at time and check the 13.5 to ground.

Pay attention to the mixer board is installed correctly. One mounting tab to the rear and two?

mounting tabs to the front of the radio.

At this point, let us know. ?

Fernando N2FQ

On Feb 21, 2025, at 09:21, dreynolds273 via groups.io <dreynolds273@...> wrote:

I have an early FT-101 SN below 25000. Problem is it has no 13.5 volts. It keeps blowing D7 and shorting D8. I have replaced them with IN4004's which seems to be what most people use. I have also replaced C6 with a same value ceramic cap. Both 10.5vac lines on the xfrmr are good. The diagram I have shows the 13.5v going to the power jack but does not show where it comes out to the rest of the system. All other voltages at the xfrmr are normal. I suspect there is a short somewhere but I have no idea where to start tracing the 13.5 through the rest of the system. Any help is appreciated.?
 

One or more of the lamps (meter, VFO, triangle) might be shorted.? That will blow the two diodes.
Nestor
VE7RSN
 

Thank you! Sounds like a solid plan. I will let you know how it goes.?
 

I will check the lamps. They do come on for a few seconds before the diodes blow. Thank you!
 

Check the bulb that is in the front panel plastic escutcheon as well, it illuminates little dial indicator triangle.? It could be shorted.? I found mine cracked.
?
Ed KN6NZW

1 - 6 of 6