View Single Post
  #7   Report Post  
Posted to alt.home.repair,sci.electronics.repair
amdx amdx is offline
external usenet poster
 
Posts: 415
Default Broken FM Xmitter?

On 4/24/2021 6:02 PM, micky wrote:
About 14 months ago, I bought something that looked like any of the
links below. It worked great, to let me listen to computer audio (such
as web-radio) anywhere in the house or even on the car radio. I used it
in my bedroom, the bathroom, and the kitchen, on different FM radios.

Left it on most of the time. Last week it broke.

https://www.amazon.com/0-5-Fail-Safe...f=sr_1_12_sspa
$120 Mine was cheaper, I guess because it had no RCA inputs, which I
have no use for.


Â*Â* I have the FM transmitter listed above. At one time it quit
transmitting.

I could not find any info on the unit at that time.

Here's the schematic as I drew it on my unit manufactured in 2011. May
or may not be correct or complete.

https://www.dropbox.com/s/8sjv8u3xls...atest.jpg?dl=0

Here's a picture of the PCB.

https://www.dropbox.com/s/o1vuhbgjcy...tion..jpg?dl=0

F1 is the output transistor, it went defective on my unit.Â* I changed it
and that fixed it. Check the voltages, at the output MosFet

If they don't match what I have on my schematic, it would be suspect. I
used part # RDO1MUS1.

https://www.mitsubishielectric.com/s...4/rd01mus1.pdf

You will also notice when it's working properly, that the 100 ohm
resistor in the L/H power switching circuit runs hot, (I think in low
power mode).

It is just poor design it is a 0.5 watt resistor dissipating 0.59 watts.

But 10 years of often hours of daily use and it is still fine. So you
can ignore that.

Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Â*Â*Â*Â*Â*Â*Â*Â*Â* Hope that helps, Mikek


--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus