On 4/28/2021 4:05 AM, micky wrote:
In alt.home.repair, on Mon, 26 Apr 2021 07:52:12 -0500, amdx
wrote:

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.
Thanks a lot for this information.

I'm saving the files you posted, and the links, for next time.

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
I might be able to do that.

Fortunately it wasn't needed this time. you probably saw that it just
needed to be reset.

OH, sorry, I must have glossed over that bit of information.

Well, anyway, I'm glad to have a searchable bit of information in case
someone else has a problem.

It was an interesting project, sense there was nothing to lean on I had
to draw the schematic and figure out how it worked.

Glad it was only the output section, if it was in the digital section, I
would have passed on it.

I tried to make a permanent post about it, but I have searched and it
doesn't pop up.

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*Â*Â*Â*Â*Â*Â* Mikek



I don't know what happened to make it stop working
at 0.5W output.

I don't even know when it happened because when the radio didn't get the
signal, I would think, Well maybe the computer is not playing anything,
and it took at least a week before I went from one room to the other to
be sure. I don't remember any power failures, plus there had been short
power failures before that didn't interfere with the xmitter working
right.


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.
LOL. Good to hear. Maybe mine will last 10+ years also. It works for
a radio in every room and outside, and even in the car parked outside,
if it's something I don't want to miss. .

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