RCA Wireless Speaker System WSP255RS

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Dah Big Dog
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RCA Wireless Speaker System WSP255RS

Post by Dah Big Dog » Wed Mar 22, 2006 4:51 pm

The system works fine for about 10 minutes. Then the transmitter shuts down. This seems like an overheating problem, or maybe a weak transistor final. I have not been able to find a schematic or any kind of technical info on this system. Any help would be much appreciated.

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jwax
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Re: RCA Wireless Speaker System WSP255RS

Post by jwax » Wed Mar 22, 2006 5:32 pm

The output stage may have a thermal shutdown built-in. Question being, why is it overheating?
Is the circuitry covered in dust? Try running with it opened up, and/or with a fan on it.
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Dah Big Dog
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Re: RCA Wireless Speaker System WSP255RS

Post by Dah Big Dog » Wed Mar 22, 2006 6:06 pm

It can't be dusty because it is a sealed saucer shaped unit. Thermal overheating probably is the problem. But, without any tech specs, I don't know if the transistor is bad or just can't handle the power requirements. The whole unit is only 4" in diameter.

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Re: RCA Wireless Speaker System WSP255RS

Post by jollyrgr » Wed Mar 22, 2006 6:41 pm

Hmmm. Does it have an external wall wart power supply and is it the right one? If it is an internal built-in supply, is the thing easily opened? If so, monitor the power supply voltage and see if the supply shuts down or if the thing simply stops transmitting.

Confirming that there is not a run away power supply voltage, you might start feeling for a semiconductor to overheat. If the power supply voltage is steady and remains so when the thing stops transmitting, likely the problem will be with a non power supply component.

Schematic? I wish you luck. I can hint that if there is an FCC ID you might get lucky and find a schematic at the FCC's web site.

See this:
https://gullfoss2.fcc.gov/prod/oet/cf/e ... Search.cfm

Beyond that, you may be out of luck. Out of curiosity, would you post the ID number?
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Dah Big Dog
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Re: RCA Wireless Speaker System WSP255RS

Post by Dah Big Dog » Wed Mar 22, 2006 6:58 pm

The wall wart does not show any signs of heat. But, I have not monitored the output voltage to see if it does drop off after a while. I will try another supply to see if it makes any difference.

The FCC ID is N0YRF93.

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jwax
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Re: RCA Wireless Speaker System WSP255RS

Post by jwax » Thu Mar 23, 2006 3:52 am

Jolly- That's a cool site! Here's the schematic:
https://gullfoss2.fcc.gov/prod/oet/form ... or_pdf=pdf
Dog- You've got to get inside the thing and see what is getting hot. Regulator? Pass transistor?
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jwax
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Re: RCA Wireless Speaker System WSP255RS

Post by jwax » Thu Mar 23, 2006 4:13 am

Also noted in the operating manual- "The transmitter will shut down if there is no audio for a 'prolonged' period".
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Re: RCA Wireless Speaker System WSP255RS

Post by Dah Big Dog » Thu Mar 23, 2006 5:44 am

jwax - Thanks for the info, it will help a lot. Now I can dig into the thing and at least know what I am looking at.

I am aware of the "no audio" feature of the xmtr. That is not the problem here.

I wonder if anyone else has had a similar problem with this system?

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Re: RCA Wireless Speaker System WSP255RS

Post by Dah Big Dog » Thu Mar 23, 2006 5:53 am

jwax - I see the web site in the link you provided, but I don't know how to search it. How did you find the diagram for my unit?

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Re: RCA Wireless Speaker System WSP255RS

Post by Dah Big Dog » Thu Mar 23, 2006 6:33 am

jwax - I see the web site in the link you provided, but I don't know how to search it. How did you find the diagram for my unit?

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philba
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Re: RCA Wireless Speaker System WSP255RS

Post by philba » Thu Mar 23, 2006 8:32 am

dog, look for the fcc id number. all rf equipment transmitting will have one on it somewhere. You can plug it into the search page. first 3 digits in grantee code, the rest in next field.

Its unfortunate that the consumer companies play fast and loose with this - I have found FCC IDs that do not correspond to the actual electronics.

It's great for hacking/scrounging rf tansmitters/transceivers/...

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Re: RCA Wireless Speaker System WSP255RS

Post by JPKNHTP » Thu Mar 23, 2006 8:34 am

-JPKNHTP
-God Bless

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jollyrgr
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Re: RCA Wireless Speaker System WSP255RS

Post by jollyrgr » Thu Mar 23, 2006 11:43 am

If the schematic is indeed for the RCA device, the BA3308 is a pre amp/limiter made by ROHM. The JRC2035 appears to be similar to the ROHM BA1404. The BA1404 is a stereo modulator circuit found in FM transmitter used to send signals to FM broadcast band stereos as well as purpose built circuits such as yours. NOTE: I DID NOT say that this was a sub chip number but a SIMILAR chip. Check the regulator IC (IC2)and note its output. See if it is overheating and going into cutoff. There is no part number on the schematic but it should be something like 5, 8, or similar volts.
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Re: RCA Wireless Speaker System WSP255RS

Post by Dah Big Dog » Thu Mar 23, 2006 1:13 pm

I want to thank all of you for your quick response and your help. It appears the problem was indeed caused by overheating which caused the circuit to shut down. The transmitting section is sealed in a metal box, which probably is also supposed to function as a heat sink. I pulled the entire circuit out and let it sit in the fresh air. Ran the unit for almost 2 hours with no problems. There was slight heating in the metal box. However, when this thing is all buttoned up, there is zero air flow, so the heating factor would be intensified. I drilled several large ventilating holes in the base and mounted larger rubber feet to improve air circulation. Just ran it for another 2 hours with excellent results. So I will assume for now that my problem is solved. Thanks again....

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Re: RCA Wireless Speaker System WSP255RS

Post by JPKNHTP » Thu Mar 23, 2006 2:11 pm

-JPKNHTP
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